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Sample records for conjugated polymer films

  1. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  2. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2010-08-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  3. Controlling Film Morphology in Conjugated Polymer

    PubMed Central

    Park, Lee Y.; Munro, Andrea M.; Ginger, David S.

    2009-01-01

    We study the effects of patterned surface chemistry on the microscale and nanoscale morphology of solution-processed donor/acceptor polymer-blend films. Focusing on combinations of interest in polymer solar cells, we demonstrate that patterned surface chemistry can be used to tailor the film morphology of blends of semiconducting polymers such as poly-[2-(3,7-dimethyloctyloxy)-5-methoxy-p-phenylenevinylene] (MDMO-PPV), poly-3-hexylthiophene (P3HT), poly[(9,9-dioctylflorenyl-2,7-diyl)-co-benzothiadiazole)] (F8BT), and poly(9,9-dioctylfluorene-co-bis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-1,4-phenylendiamine) (PFB) with the fullerene derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We present a method for generating patterned, fullerene-terminated monolayers on gold surfaces, and use microcontact printing and Dip-Pen Nanolithography (DPN) to pattern alkanethiols with both micro- and nanoscale features. After patterning with fullerenes and other functional groups, we backfill the rest of the surface with a variety of thiols to prepare substrates with periodic variations in surface chemistry. Spin coating polymer:PCBM films onto these substrates, followed by thermal annealing under nitrogen, leads to the formation of structured polymer films. We characterize these films with Atomic Force Microscopy (AFM), Raman spectroscopy, and fluorescence microscopy. The surface patterns are effective in guiding phase separation in all of the polymer:PCBM systems investigated, and lead to a rich variety of film morphologies that are inaccessible with unpatterned substrates. We demonstrate our ability to guide pattern formation in films thick enough of be of interest for actual device applications (up to 200 nm in thickness) using feature sizes as small as 100 nm. Finally, we show that the surface chemistry can lead to variations in film morphology on length scales significantly smaller than those used in generating the original surface patterns. The variety of

  4. Organic thin film transistor by using polymer electrolyte to modulate the conductivity of conjugated polymer

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Ju; Li, Yu-Chang; Yeh, Chih-Chieh; Chung, Sheng-Feng; Huang, Li-Ming; Wen, Ten-Chin; Wang, Yeong-Her

    2006-11-01

    This work presents an organic thin film transistor using double polymer layers, polymer electrolyte/conjugated polymer, i.e., poly(diallyldimethylammonium chloride) (PDDA)/poly(diphenylamine) (PDPA) structure. The single mobile anions (Cl-) pending on the PDDA are stuffed into the conjugated polymer to dope the nitrogen atoms (imine) by applying the gate bias, resulting a higher drain current under the same source-drain voltage. The PDDA/PDPA polymer structure working in the enhancement mode which operates under atmospheric conditions as a typical p-channel transistor is demonstrated.

  5. Microwave absorption of free carriers in doped conjugated polymer films

    NASA Astrophysics Data System (ADS)

    Rumbles, Garry

    Flash photolysis time-resolved microwave conductivity (fp-TRMC) is a powerful spectroscopic tool for the detection of mobile charges in organic systems, such as conjugated polymers. We will report on a study of charge carrier generation in a number of polymer systems where the solid-state microstructure (SSM) of the thin films can be controlled using both molecular structure and processing conditions. By incorporating a low concentration of molecular acceptors, such as metallo-phthalocyanines, as well as substituted fullerenes and perylenes, the driving force for photoinduced electron transfer can be controlled through the excited state energy and the reduction potential. Our results indicate the importance of the crystalline phase of the polymer to stabilise and reduce the rate of recombination of the holes with the electrons that remain trapped on the acceptor. In addition, the role that the SSM plays on the stabilization of bound electron-hole pairs, or charge-transfer (CT) states will be examined.

  6. Electrochemically polymerized conjugated polymer films: Stability improvement and surface functionalization

    NASA Astrophysics Data System (ADS)

    Wei, Bin

    Conjugated polymers have been widely used in various applications including organic solar cells, electrochromic devices, chemical sensors, and biomedical devices. Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have received considerable interest because of their low oxidation potential, relatively high chemical stability, and high conductivity. Electrochemical deposition is a convenient method for precisely fabricating conjugated polymer thin films. Here, we report the stability improvement and surface functionalization of electrochemically polymerized PEDOT films. The long-term performance of PEDOT coatings is limited by their relatively poor stability on various inorganic substrates. Two different methods were used to improve the stability of PEDOT coatings, one involved using carboxylic acid functionalized EDOT (EDOT-acid) as adhesion promoter. EDOT-acid molecules were chemically bonded onto activated metal oxide substrates via chemisorption. PEDOT was then polymerized onto the EDOT-acid modified substrates, forming covalently bonded coatings. An aggressive ultrasonication test confirmed the significantly improved adhesion of the PEDOT films on electrodes with EDOT-acid treatment over those without treatment. The other method was to use an octa-ProDOT-functionalized POSS derivative (POSSProDOT) as cross-linker. PEDOT copolymer films were electrochemically deposited with various concentrations of POSS-ProDOT. The optical, morphological and electrochemical properties of the copolymer films could be systematically tuned with the incorporation of POSS-ProDOT. Significantly enhanced electrochemical and mechanical stability of the copolymers were observed at intermediate levels of POSS-ProDOT content (3.1 wt%) via chronic stimulation tests. Surface functionalization of conducting polymer films provides a potential means for systematically tailoring their chemical and physical properties. We have synthesized, polymerized and characterized a dialkene

  7. Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

    DOE PAGES

    Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.; ...

    2017-08-01

    Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2-b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coating direction.more » The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.« less

  8. Nanoparticles of conjugated polymers prepared from phase-separated films of phospholipids and polymers for biomedical applications.

    PubMed

    Yoon, Jungju; Kwag, Jungheon; Shin, Tae Joo; Park, Joonhyuck; Lee, Yong Man; Lee, Yebin; Park, Jonghyup; Heo, Jung; Joo, Chulmin; Park, Tae Jung; Yoo, Pil J; Kim, Sungjee; Park, Juhyun

    2014-07-09

    Phase separation in films of phospholipids and conjugated polymers results in nanoassemblies because of a difference in the physicochemical properties between the hydrophobic polymers and the polar lipid heads, together with the comparable polymer side-chain lengths to lipid tail lengths, thus producing nanoparticles of conjugated polymers upon disassembly in aqueous media by the penetration of water into polar regions of the lipid heads.

  9. Electrochemical route to fabricate film-like conjugated microporous polymers and application for organic electronics.

    PubMed

    Gu, Cheng; Chen, Youchun; Zhang, Zhongbo; Xue, Shanfeng; Sun, Shuheng; Zhang, Kai; Zhong, Chengmei; Zhang, Huanhuan; Pan, Yuyu; Lv, Ying; Yang, Yanqin; Li, Fenghong; Zhang, Suobo; Huang, Fei; Ma, Yuguang

    2013-07-05

    Film-like conjugated microporous polymers (CMPs) are fabricated by the novel strategy of carbazole-based electropolymerization. The CMP film storing a mass of counterions acting as an anode interlayer provides a significant power-conversion efficiency of 7.56% in polymer solar cells and 20.7 cd A(-1) in polymer light-emitting diodes, demonstrating its universality and potential as an electrode interlayer in organic electronics.

  10. Conjugated Polymer Solar Cells

    DTIC Science & Technology

    2006-05-01

    for films was measured in a pumped vacuum cell. The quantum yield was calculated from the integrated PL spectra and measured optical density...At the same time, the known disadvantages of pristine conjugated polymers are: • the quantum yield of free charges is far below than unity under...possibility of improving the photovoltaic properties of conjugated polymers using polymer CTCs. EXPECTED RESULTS We planned to perform a well -directed

  11. Cellulose nanofibril based graft conjugated polymer films act as a chemosensor for nitroaromatic.

    PubMed

    Niu, Qingyuan; Gao, Kezheng; Wu, Wenhui

    2014-09-22

    A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensor's out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility.

  12. Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

    NASA Astrophysics Data System (ADS)

    Sreeram, Arvind

    Conjugated polymers have found several applications in recent years, in energy conversion and storage devices such as organic light emitting diodes, solar cells, batteries, and super capacitors. Thin films of polymers used for these applications need to be mechanically and thermally stable to withstand the harsh operating conditions. Although there is significant information on the optoelectronic properties of many of these polymers, there are only few studies on their mechanical properties. There is little information in the literature on how processing of these films influence mechanical properties. In the first part of this study, poly(p-phenylene vinylene) (PPV) films were prepared by thermolytic conversion of poly[p -phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures and the kinetics of reaction was investigated using thermogravimetry and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties of the films, studied using nanoindentation, showed a dependence on the extent of conversion and chemical composition of the films. The presence of chemical defects (e.g., carbonyl groups, detected using FTIR spectroscopy), was also found to have a noticeable effect on the modulus and hardness of the films. The storage modulus, E', and plasticity decreased with an increase in conversion, whereas the loss modulus, E", showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E" than E', consistent with the glassy nature of the polymers at room temperature. In the second part of the study, polyacetylene films were synthesized by acid-catalyzed dehydration reaction of poly(vinyl alcohol) (PVA) precursor films. The kinetics of this reaction was monitored by thermogravimetry. The chemical structure of the conjugated polymer films was characterized by Raman and IR spectroscopy. Polyacetylene films incorporated with 1-propyl-3-methylimidazolium ionic liquid

  13. Measuring Exciton Diffusion in Conjugated Polymer Films with Super-resolution Microscopy

    NASA Astrophysics Data System (ADS)

    Penwell, Samuel; Ginsberg, Lucas; Noriega Manez, Rodrigo; Ginsberg, Naomi

    2015-03-01

    Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion microscopy. STED is typically used in biology with well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated STED in conjugated polymer films of MEH-PPV and CN-PPV by taking care to first understand the film's photophysical properties. This new approach provides a way to study exciton diffusion by utilizing subdiffraction optical excitation volumes. In this way, we will obtain a spatiotemporal map of exciton distributions that will help to correlate the energetic landscape to film morphology at the nanoscale. This research is supported in part by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under Contract No. DE-AC05-06.

  14. Deviations of the glass transition temperature in amorphous conjugated polymer thin films

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Osuna Orozco, Rodrigo; Wang, Tao

    2013-08-01

    The deviations of the glass transition temperature (Tg) in thin films of an amorphous conjugated polymer poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) are reported. Monotonic and nonmonotonic Tg deviations are observed in TFB thin films supported on Si-SiOx and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), respectively. A three-layer model is developed to fit both monotonic and nonmonotonic Tg deviations in these films. A 5-nm PEDOT:PSS capping layer was not found to be effective to remove the free-surface effect in Si-SiOx supported TFB films.

  15. Measuring Exciton Migration in Conjugated Polymer Films with Ultrafast Time Resolved Stimulated Emission Depletion Microscopy

    NASA Astrophysics Data System (ADS)

    Penwell, Samuel

    Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion (STED) microscopy. STED is typically used in biology with sparse well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated the extension of STED to conjugated polymer films and nanoparticles of MEH-PPV and CN-PPV, despite the presence of two photon absorption, by taking care to first understand the material's photophysical properties. We then further adapt this approach, by introducing a second ultrafast STED pulse at a variable delay. Excitons that migrate away from the initial subdiffraction excitation volume during the ps-ns time delay, are preferentially quenched by the second STED pulse, while those that remain in the initial volume survive. The resulting effect of the second STED pulse is modulated by the degree of migration over the ultrafast time delay, thus providing a new method to study exciton migration. Since this technique utilizes subdiffraction optical excitation and detection volumes with ultrafast time resolution, it provides a means of spatially and temporally resolving measurements of exciton migration on the native length and time scales. In this way, we will obtain a spatiotemporal map of exciton distributions and migration that will help to correlate the energetic landscape to film morphology at the nanoscale.

  16. Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

    PubMed Central

    Qu, Jing; Ouyang, Liangqi; Kuo, Chin-chen; Martin, David C.

    2015-01-01

    Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this study the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7 ± 0.3 MPa was determined. The addition of 5 mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4 ± 0.6 MPa. PMID:26607768

  17. Critical Role of Surface Energy in Guiding Crystallization of Solution Coated Conjugated Polymer Thin Films.

    PubMed

    Zhang, Fengjiao; Mohammadi, Erfan; Luo, Xuyi; Strzalka, Joseph; Mei, Jianguo; Diao, Ying

    2017-10-02

    It is well-known that substrate surface properties have a profound impact on morphology of thin films solution coated atop and the resulting solid-state properties. However, design rules for guiding the substrate selection have not yet been established. Such design rules are particularly important for solution coated semiconducting polymers, as the substrate-directed thin film morphology can impact charge transport properties by orders of magnitude. We hypothesize that substrate surface energies dictate the thin film morphology by modulating the free energy barrier to heterogeneous nucleation. To test this hypothesis, we systematically vary the substrate surface energy via surface functionalization techniques. We perform in-depth morphology and device characterizations to establish the relationship between substrate surface energy, thin film morphology and charge transport properties, employing a donor-accepter (D-A) conjugated polymer. We find that decreasing the substrate surface energy progressively increases thin film crystallinity, degree of molecular ordering and extent of domain alignment. Notably, the enhanced morphology on the lowest surface energy substrate lead to a 10-fold increase in the charge carrier mobility. We further develop a free energy model relating the substrate surface energy to the penalty of heterogeneous nucleation from solution in the thin film geometry. The model correctly predicts the experimental trend, thereby validating our hypothesis. This work is a significant step towards establishing design rules and understanding the critical role of substrates in determining morphology of solution coated thin films.

  18. Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films.

    PubMed

    Qu, Jing; Ouyang, Liangqi; Kuo, Chin-Chen; Martin, David C

    2016-02-01

    Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this paper, the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young's modulus of the PEDOT films was 2.6±1.4GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56±27MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7±0.3MPa was determined. The addition of 5mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283±67MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4±0.6MPa. This paper describes methods for estimating the ultimate mechanical properties of electrochemically deposited conjugated polymer (here PEDOT and PEDOT copolymers) films. Of particular interest and novelty is our implementation of a cracking test to quantify the shear strength of the PEDOT thin films on these solid substrates. There is considerable interest in these materials as interfaces between biomedical devices and living tissue, however potential mechanisms and modes of failure are areas of continuing concern, and establishing methods to quantify the strengths of these interfaces are therefore of particular current interest. We are confident that these results will be useful

  19. Highly aligned conjugated polymer films prepared by rotation coating for high-performance organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Van Tho, Luu; Park, Won-Tae; Choi, Eun-Young; Noh, Yong-Young

    2017-04-01

    Recently, exceptionally high field-effect mobility in organic field-effect transistors (OFETs) has been fabricated using semiconducting films with one-dimensionally aligned, highly planar electron donor-acceptor copolymers, within the channel of transistors. Here, we propose an extremely simple coating method, called rotation coating, for preparing highly aligned, conjugated polymer thin films for applications in various organic electronic devices. We realize highly aligned polymer films using various conjugated polymers and applied the films as active layers for high-performance OFETs. Significantly high field-effect mobility values of 1.45 ± 0.46 cm2/Vs have been achieved for rotation coated diketopyrrolopyrrole-thieno[3,2-b]thiophene copolymer films.

  20. Mimicking conjugated polymer thin-film photophysics with a well-defined triblock copolymer in solution.

    PubMed

    Brazard, Johanna; Ono, Robert J; Bielawski, Christopher W; Barbara, Paul F; Vanden Bout, David A

    2013-04-25

    Conjugated polymers (CPs) are promising materials for use in electronic applications, such as low-cost, easily processed organic photovoltaic (OPV) devices. Improving OPV efficiencies is hindered by a lack of a fundamental understanding of the photophysics in CP-based thin films that is complicated by their heterogeneous nanoscale morphologies. Here, we report on a poly(3-hexylthiophene)-block-poly(tert-butyl acrylate)-block-poly(3-hexylthiophene) rod-coil-rod triblock copolymer. In good solvents, this polymer resembles solutions of P3HT; however, upon the addition of a poor solvent, the two P3HT chains within the triblock copolymer collapse, affording a material with electronic spectra identical to those of a thin film of P3HT. Using this new system as a model for thin films of P3HT, we can attribute the low fluorescence quantum yield of films to the presence of a charge-transfer state, providing fundamental insights into the condensed phase photophysics that will help to guide the development of the next generation of materials for OPVs.

  1. Mimicking Conjugated Polymer Thin Film Photophysics with a Well-Defined Triblock Copolymer in Solution

    SciTech Connect

    Brazard, Johanna; Ono, Robert J.; Bielawski, Christopher W.; Barbara, Paul F.; Vanden Bout, David A.

    2013-04-25

    Conjugated polymers (CPs) are promising materials for use in electronic applications, such as low-cost, easily processed organic photovoltaic (OPV) devices. Improving OPV efficiencies is hindered by a lack of a fundamental understanding of the photophysics in CP-based thin films that is complicated by their heterogeneous nanoscale morphologies. Here, we report on a poly(3-hexylthiophene)-block-poly(tert-butyl acrylate)-block-poly(3-hexylthiophene) rod–coil–rod triblock copolymer. In good solvents, this polymer resembles solutions of P3HT; however, upon the addition of a poor solvent, the two P3HT chains within the triblock copolymer collapse, affording a material with electronic spectra identical to those of a thin film of P3HT. Using this new system as a model for thin films of P3HT, we can attribute the low fluorescence quantum yield of films to the presence of a charge-transfer state, providing fundamental insights into the condensed phase photophysics that will help to guide the development of the next generation of materials for OPVs.

  2. Isotope effect in spin response of pi-conjugated polymer films and devices.

    PubMed

    Nguyen, Tho D; Hukic-Markosian, Golda; Wang, Fujian; Wojcik, Leonard; Li, Xiao-Guang; Ehrenfreund, Eitan; Vardeny, Z Valy

    2010-04-01

    Recent advances in organic spin response include long polaron spin-coherence times measured by optically detected magnetic resonance (ODMR), substantive room-temperature magnetoelectroluminescence and magnetoconductance obtained in organic light-emitting diodes (OLEDs) and spin-polarized carrier injection from ferromagnetic electrodes in organic spin valves (OSVs). Although the hyperfine interaction (HFI) has been foreseen to have an important role in organic spin response, no clear experimental evidence has been reported so far. Using the chemical versatility advantage of the organics, we studied and compared spin responses in films, OLED and OSV devices based on pi-conjugated polymers made of protonated, H-, and deuterated, D-hydrogen having a weaker HFI strength. We demonstrate that the HFI does indeed have a crucial role in all three spin responses. OLED films based on the D-polymers show substantially narrower magneto-electroluminescence and ODMR responses, and as a result of the longer spin diffusion obtained, OSV devices based on D-polymers show a substantially larger magnetoresistance.

  3. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  4. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  5. Electrochemical spectroscopy of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Hwang, Jungseek

    Conjugated polymers become conductors when they are doped (oxidized or reduced). The initial work was done on conducting polymers by three Nobel laureates (A. J. Heeger, H. Shirakawa, and A. G. MacDiarmid) in 1977. They discovered an increase by nearly 10 orders of magnitude in the electrical conductivity of polyacetylene when it was doped with iodine or other acceptors. Conjugated polymers have been studied intensively since that time because of their high conductivity, reversible doping and low-dimensional geometry. Doping causes electronic structure changes which have numerous potential applications. We have studied three thiophene derivative polymers: poly (3,4-ethylenedioxy-thiophene) (PEDOT), poly (3,4-propylenedioxythiophene) (PProDOT), and poly (3,4-dimethylpropylenedioxythiophene) (PProDOTMe2). Two types of samples were used for this study. The first was a thin polymer film on an indium tin oxide (ITO) coated glass slide. The polymer film was deposited on a metallic ITO surface by an electrochemical method. We measured reflectance and transmittance of the sample. The data were analyzed by modeling all layers of this multi-layer thin film structure, using the Drude-Lorentz model for each layer. We calculated the optical constants from the modeling results and obtained information on the electronic structure of the neutral and doped polymers. Conjugated polymers can be reversibly doped in an electrochemical cell. The doping causes optical absorption bands to move from one optical frequency to another frequency. To study this behavior, we prepared another type of sample. First, a thin polymer film was deposited on a gold-coated Mylar film by the same electrochemical method. Then, we built electrochromic cells with an infrared transparent window, using the polymer films on the gold/Mylar strips as electrodes. We connected the cell to an electrical supply. As we change the cell voltage (potential difference between the two electrodes), we can change the doping

  6. Aqueous dispersion of conjugated polymers by colloidal clays and their film photoluminescence.

    PubMed

    Lan, Yi-Fen; Lee, Rong-Ho; Lin, Jiang-Jen

    2010-02-11

    The plate-shaped clays enabled us to disperse water-insoluble conjugated polymers (CPs) into a colloidal form and an aqueous process for making CP films. Simple pulverization of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with silicate clays rendered the powder mixture an unusual dispersing behavior in water. The most effective clay was selected from screening several natural and synthetic clays including synthetic fluorinated mica (Mica), sodium montmorillonite (MMT), synthetic smectite (SWN), and cationic layered double hydroxide (LDH). A high aspect ratio and intensive charge density (2.1 e nm(-1)) of Mica were highly effective for promoting the CP dispersion. The enhancement for dispersing MEH-PPV is rated in the following trend: Mica > MMT > SWN > LDH. The result is rationalized by the influences of their geometric shape and ionic charge of clay on MEH-PPV in water. Two other representative CPs, sulfonated polyaniline (SPA) and triphenyl phosphine oxide cored polyaniline (TPOPA), were used to generalize the CP/clay colloidal behavior. All of the three CPs as in an aqueous form can be coated into hybrid films. Under an ultraviolet lamp, these films showed color emissions, orange for MEH-PPV/Mica, olive for SPA/Mica, and green for TPOPA/Mica, which are consistent with the photoluminescence measurements.

  7. Controlled synthesis of conjugated microporous polymer films: versatile platforms for highly sensitive and label-free chemo- and biosensing.

    PubMed

    Gu, Cheng; Huang, Ning; Gao, Jia; Xu, Fei; Xu, Yanhong; Jiang, Donglin

    2014-05-05

    Conjugated microporous polymers (CMPs), in which rigid building blocks form robust networks, are usually synthesized as insoluble and unprocessable powders. We developed a methodology using electropolymerization for the synthesis of thin CMP films. The thickness of these films is synthetically controllable, ranging from nanometers to micrometers, and they are obtained on substrates or as freestanding films. The CMP films combine a number of striking physical properties, including high porosity, extended π conjugation, facilitated exciton delocalization, and high-rate electron transfer. We explored the CMP films as versatile platforms for highly sensitive and label-free chemo- and biosensing of electron-rich and electron-poor arenes, metal ions, dopamine, and hypochloroic acid, featuring rapid response, excellent selectivity, and robust reusability.

  8. Fluorescence enhancement of the conjugated polymer films based on well-ordered Au nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Zhong, Benbin; Zu, Xihong; Yi, Guobin; Huang, Hailiang; Zhang, Minghai; Luo, Hongsheng

    2016-09-01

    In this paper, well-ordered Au nanoparticle arrays on silicon substrates were employed as efficient metal-enhanced fluorescence (MEF) substrates for investigating the fluorescence properties of the conjugated polymer poly(3-hexylthiophene) (P3HT). The ordered Au nanoparticle arrays were fabricated by block copolymer self-assembly technology, and the particle sizes were controlled by adjusting the molar ratios of HAuCl4 precursor to vinyl pyridine units. The approach is economical and suitable to fabricate large-area MEF substrates. The results about fluorescence properties of P3HT showed that the fluorescence intensities of the P3HT films were improved on ordered Au nanoparticle arrays compared to those on bare silicon substrate and were significantly enhanced with the Au nanoparticle sizes increasing. The mechanism is based on localized surface plasmon resonances, coupling and propagating surface plasmons, and the emission enhancement mainly resulted from the increase of the excitation rate. This work provides a new way to prepare efficient MEF substrates for high-performance fluorescence-based devices.

  9. Covalent polymer-drug conjugates.

    PubMed

    Elvira, Carlos; Gallardo, Alberto; Roman, Julio San; Cifuentes, Alejandro

    2005-01-31

    In this work, polymer-drugs conjugates used as drug delivery systems (DDS) are revised attending to their chemical conjugation. Namely, the classification of this type of DDS is based on the conjugation sites of the reactive groups (i.e., via end groups or pendant polymer groups). Advantages and limitations of these types of DDS are discussed through representative examples of polymer-drugs and polymer-proteins conjugates recently developed.

  10. Processing Cyclic Peptide-polymer Conjugates in Block Copolymer Thin Films for Sub-nm Porous Membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Xu, Ting

    2014-03-01

    Porous thin films containing subnanometer channels oriented normal to the surface exhibit unique transport and separation properties and can serve as selective membranes for separation. Inspired by natural protein channels, we have developed an approach using cyclic peptide nanotubes (CPNs) embedded in polymeric matrix to mimic the transport of natural channels. The co-assembly of polymer-covered CPNs in a block copolymer (BCP) thin film requires the synchronization of two self-assembly processes, namely the microphase separation of BCP and the nanotube growth of CP-polymer conjugates. We systematically investigated the co-assembly of isolated CP-poly(ethylene glycol) (CP-PEG) conjugates and polystyrene-b-poly (methyl methacrylate) (PS-b-PMMA) in thin films as a function of CP-PEG loading (fCP-PEG) and solvent-polymer interactions. We find that there is a strong dependence of the co-assembly process on fCP-PEG due to thermodynamic limit of incorporating one CPN in one PMMA microdomain, as well as the kinetic pathway in which favorable PEG-solvent interaction helps to disperse CPNs and thus lowers the activation energy barrier of the system. This study presents critical insights in guided assemblies of functional building blocks within nanoscopic frameworks. DOE-EFRC-Gas Separation, Army Research Office.

  11. Synthesis of cyanopyridine based conjugated polymer

    PubMed Central

    Hemavathi, B.; Ahipa, T.N.; Pillai, Saju; Pai, Ranjith Krishna

    2016-01-01

    This data file contains the detailed synthetic procedure for the synthesis of two new cyanopyridine based conjugated polymer P1 and P2 along with the synthesis of its monomers. The synthesised polymers can be used for electroluminescence and photovoltaic (PV) application. The physical data of the polymers are provided in this data file along with the morphological data of the polymer thin films. The data provided here are in association with the research article entitled ‘Cyanopyridine based conjugated polymer-synthesis and characterisation’ (Hemavathi et al., 2015) [3]. PMID:27158642

  12. Influence of Morphological Disorder on In- and Out-of-Plane Charge Transport in Conjugated Polymer Films

    NASA Astrophysics Data System (ADS)

    Dong, Ban; Li, Anton; Green, Peter

    We report the unequal impacts of morphological disorder on in- and out-of-plane charge transport in thin films of poly(3-hexylthiophene) (P3HT) fabricated by both conventional spin-casting and the novel technique Matrix-Assisted Pulsed Laser Evaporation (MAPLE). MAPLE produces films with inhomogeneous globular subfeatures with dimensions on the order of 100 nm. Optical absorbance spectroscopy corroborates that MAPLE-deposited films are more energetically disordered, but possesses average conjugation lengths comparable to spin-cast P3HT. Both in- and out-of-plane carrier transport measurements of MAPLE-deposited films show characteristics that reflect a higher degree of energetic disorder and broadened density of states. Whereas in-plane carrier mobilities of MAPLE-deposited thin-film transistors are comparable to spin-cast analogues (8.3 x 10-3 cm2V-1s-1 versus 5.5 x 10-3 cm2V-1s-1) , the out-of-plane mobilities of MAPLE-deposited samples are nearly an order of magnitude lower (4.1 x 10-4 cm2V-1s-1 versus 2.7 x 10-3 cm2V-1s-1) . The unusual ensemble of properties and behaviors arising from the unique morphologies produced by MAPLE provide important perspectives on the extent to which disorder impacts different mechanisms of charge transport in conjugated polymers.

  13. Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

    SciTech Connect

    Dong, Ban Xuan; Li, Anton; Strzalka, Joseph; Stein, Gila E.; Green, Peter F.

    2016-09-18

    The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations and the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.

  14. Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

    SciTech Connect

    Dong, Ban Xuan; Li, Anton; Strzalka, Joseph; Stein, Gila E.; Green, Peter F.

    2016-09-18

    The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations and the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.

  15. Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

    DOE PAGES

    Dong, Ban Xuan; Li, Anton; Strzalka, Joseph; ...

    2016-09-18

    The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less

  16. Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

    PubMed

    Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

    2015-02-11

    New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

  17. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  18. Solvent Polarity Effect on Chain Conformation, Film Morphology, and Optical Properties of a Water-Soluble Conjugated Polymer

    SciTech Connect

    Xu, Zhihua; Tsai, Hsinhan; Wang, Hsing-Lin; Cotlet, Mircea

    2010-09-16

    The solvent polarity effect on chain conformation, film morphology, and photophysical properties of a nonionic water-soluble conjugated polymer (WSCP), poly[2,5-bis(diethylaminetetraethylene glycol)phenylene vinylene] (DEATG-PPV) is investigated in detail. The combination of stationary absorption and photoluminescence (PL) spectroscopy, time-resolved PL spectroscopy, and fluorescence correlation spectroscopy methods enables us to probe the chain conformation of DEATG-PPV, down to the level of a single chain when working with extremely diluted solutions. The use of correlated atomic force microscopy and confocal fluorescence lifetime imaging microscopy measurements of drop-casted DEATG-PPV films reveals the intrinsic relationship between chain conformation, film morphology, and optical properties. Depending on solvent polarity, DEATG-PPV presents extended, coiled, and collapsed chain conformations in solutions, which lead to distinct morphology and optical properties in solid films. Our work presents a pathway to control and characterize the film morphologies of WSCPs toward the optimal performance of various optoelectronic devices.

  19. Compositions for directed alignment of conjugated polymers

    DOEpatents

    Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

    2016-04-19

    Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

  20. Electroabsorption in Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Worland, Rand S.

    This dissertation presents the results of a series of electroabsorption measurements on the following conjugated polymers: trans-polyacetylene (unoriented and oriented), poly(3-hexylthiophene), poly(p-phenylene vinylene) and poly(2,5-dimethoxy-p-phenylene vinylene). The data are used to determine various nonlinear optical terms for these materials, including the electric field induced changes in the complex index of refraction and the complex dielectric function. The third order nonlinear susceptibility, chi ^{(3)}, and the electrooptic Kerr coefficient, K, are also evaluated as an aid in determining the usefulness of these materials in electrooptic device technology. Of the materials studied, the largest electroabsorption response is seen with trans-polyacetylene. The electroabsorption signal occurs near the band edge in each case, with a lineshape which may be approximated by a second derivative (with respect to photon energy) of the unperturbed absorption curve. Anisotropy of the electroabsorption response is obtained by varying the polarization of the incident light with respect to the axis defined by the applied electric field. Temperature, field strength, modulation frequency and light intensity dependences are also reported. The experimental techniques and methods of analysis are described in detail, along with suggestions for future electroabsorption and electroreflectance measurements on organic conducting polymers.

  1. Enhanced photophysics of conjugated polymers

    SciTech Connect

    Chen, Liaohai; Xu, Su; McBranch, Duncan; Whitten, David

    2003-05-27

    The addition of oppositely charged surfactant to fluorescent ionic conjugated polymer forms a polymer-surfactant complex that exhibits at least one improved photophysical property. The conjugated polymer is a fluorescent ionic polymer that typically has at least one ionic side chain or moiety that interacts with the specific surfactant selected. The photophysical property improvements may include increased fluorescence quantum efficiency, wavelength-independent emission and absorption spectra, and more stable fluorescence decay kinetics. The complexation typically occurs in a solution of a polar solvent in which the polymer and surfactant are soluble, but it may also occur in a mixture of solvents. The solution is commonly prepared with a surfactant molecule:monomer repeat unit of polymer ratio ranging from about 1:100 to about 1:1. A polymer-surfactant complex precipitate is formed as the ratio approaches 1:1. This precipitate is recoverable and usable in many forms.

  2. Impact of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE) on Morphology and Charge Conduction in Conjugated Polymer and Bulk Heterojunction Thin Films

    NASA Astrophysics Data System (ADS)

    Stiff-Roberts, Adrienne; McCormick, Ryan; Atewologun, Ayomide

    2014-03-01

    An approach to improve organic photovoltaic efficiency is to increase vertical charge conduction by promoting out-of-plane π- π stacking in conjugated polymers. Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) features multiple growth parameters that can be varied to achieve a desired organic thin film property. In addition, RIR-MAPLE enables nanoscale domains in blended polymeric films and multi-layer polymeric films regardless of constituent solubility. Thus, RIR-MAPLE deposition is compared to solution-cast films as a possible approach to increase out-of-plane charge transport in polymers and bulk heterojunctions. Two common, solar cell polymers are investigated: P3HT and PCPDTBT. Materials characterization includes grazing-incidence, wide angle x-ray scattering (GIWAXS) for structural information and two techniques to determine hole mobility: organic field effect transistors to measure in-plane mobility and charge extraction by linearly increasing voltage to measure out-of-plane mobility. Initial indications are that the RIR-MAPLE films have a fundamentally different morphology compared to solution-cast films. In the case of P3HT, an enhancement in out-of-plane π- π stacking was observed by GIWAXS in RIR-MAPLE films compared to solution-cast films. A portion of this research was conducted at CNMS at ORNL.

  3. Magnetism in (Semi)Conducting Macrocycles of pi conjugated Polymers

    DTIC Science & Technology

    2016-12-09

    the investigation of potential magnetic properties of macrocycles of pi-conjugated polymers. This research was initially motivated by the observation ...the subsequently observed ferromagnetic hysteretic behavior at low temperature (T < 20k) in these polymers. Concomitantly nanoscopic doughnut...structures ( ~12 nm) in spincoated thin films of these polymers were observed by AFM. Interestingly the magnetic properties and doughnut structures are

  4. Local Electronic Characterization of Conjugated Polymer Films using Conducting-Probe Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    O'Brien, G.; Quinn, A. J.; Redmond, G.

    2004-03-01

    Correlation of local electronic properties with film morphology is a key challenge to be addressed in order to understand (and therefore control) charge injection, transport and recombination in organic electronic devices. We present a flexible method, Conducting-Probe Atomic Force Microscopy (CP-AFM), which can be used as a local probe of both film morphology and spectroscopy. MEH-PPV layers with thickness values comparable to films used in organic electronic devices (60 nm) are spun onto gold substrates under inert conditions. Tip-height vs bias voltage (z-V) sweeps taken at constant tunnel current (50 pA) show clear charge injection thresholds at both positive and negative bias (E_+,E_-). Statistical analysis of measured single-particle gap energies, E_gsp=E_+-E_-, reveals a distribution across the surface with peaks corresponding to (extracted) exciton binding energies of 100 meV and 400 meV respectively. Analysis of measured E_gsp values for films prepared under ambient conditions show a large density of mid-gap states confirming that the preparation route is critical for organic electronic devices.

  5. Enhanced photophysics of conjugated polymers

    DOEpatents

    Chen, Liaohai

    2007-06-12

    A particulate fluorescent conjugated polymer surfactant complex and method of making and using same. The particles are between about 15 and about 50 nm and when formed from a lipsome surfactant have a charge density similar to DNA and are strongly absorbed by cancer cells.

  6. Nanostructured conjugated polymers for photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Xi, Dongjuan

    This dissertation focuses on making new systems of interdigitated bilayer structures for organic solar cells from two aspects: (i) fabricating vertically aligned semiconductor nanorod arrays by low-temperature solution process; (ii) applying the resulting nanorods arrays in solar cell devices with pre-formed or in-situ electropolymerized conjugated polymers. Two low-temperature solution methods are investigated to fabricate vertically aligned semiconductor nanorod arrays. The first method is using porous templates to prepare vertically aligned conjugated polymer nanorods arrays. In-situ anodized nanoporous alumina film is specifically designed to suspend on substrates to improve the wettability of organic solution to the alumina film, and to generate a big foot anchoring the polymer nanorods. With this specific design, vertically aligned polymer nanotube arrays with high density, 3x1010/cm2, is achieved and the nanotubes can stand vertically at the aspect ratio of 5. The second method is low-temperature direct growth of high quality semiconductor nanorod arrays without any templates by electrochemical deposition. Vertically aligned cadmium sulfide nanorod arrays are achieved by studying the growth mechanism of cadmium sulfide nanocrystal deposition and fine tuning the solution composition of the electrolyte. Chlorine doping, as a function of chlorine ion concentration in the electrolyte, modifies crystal lattice, and therefore the build-in stress, which dominates the morphology of the deposited nanocrystals as nanorods or thin films. Scanning electron microscopy, x-ray diffraction and transmission electron microscopy are applied to study the microstructures of the nanorods. Optical, electrical and field emission properties of the cadmium sulfide nanorod arrays are also studied in detail to pursue further applications of the nanorod arrays as nano-lasers and cold field emitters. Organic solar cells based on template-processed polythiophene nanotube arrays will be

  7. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    DOE PAGES

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei; ...

    2017-07-13

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template–polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results inmore » highly aligned, highly crystalline donor-acceptor polymer thin films over large area (41cm2) and promoted charge transport along both the polymer backbone and the π-π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment.« less

  8. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    NASA Astrophysics Data System (ADS)

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei; Qu, Ge; Zhang, Fengjiao; Zhao, Xikang; Mei, Jianguo; Zuo, Jian-Min; Shukla, Diwakar; Diao, Ying

    2017-07-01

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template-polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results in highly aligned, highly crystalline donor-acceptor polymer thin films over large area (>1 cm2) and promoted charge transport along both the polymer backbone and the π-π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment.

  9. Solution assembly of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Bokel, Felicia A.

    This dissertation focuses on the solution-state polymer assembly of conjugated polymers with specific attention to nano- and molecular-scale morphology. Understanding how to control these structures holds potential for applications in polymer-based electronics. Optimization of conjugated polymer morphology was performed with three objectives: 1) segregation of donor and acceptor materials on the nanometer length-scale, 2) achieving molecular-scale ordering in terms of crystallinity within distinct domains, and 3) maximizing the number and quality of well-defined donor/acceptor interfaces. Chapter 1 introduces the development of a mixed solvent method to create crystalline poly(3-hexyl thiophene) (P3HT) fibrils in solution. Chapter 2 describes fibril purification and approaches to robust and functional fibrils, while chapters 3 and 4 demonstrate the formation of hybrid nanocomposite wires of P3HT and cadmium selenide (CdSe) nanoparticles by two methods: 1) co-crystallization of free and P3HT-grafted CdSe for composite nanowires and 2) direct attachment of CdSe nanoparticles at fibril edges to give superhighway structures. These composite structures show great potential in the application of optoelectronic devices, such as the active layer of solar cells. Finally, ultrafast photophysical characterization of these polymers, using time-resolved photoluminescence and transient absorption, was performed to determine the aggregation types present in suspended fibrils and monitor the formation and decay of charged species in fibrils and donor-acceptor systems.

  10. Photoluminescence of Conjugated Star Polymers

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Prigodin, N. V.; Epstein, A. J.; Wang, F.

    2000-10-01

    Higher dimensionality "star" polymers provide new properties beyond those found in their linear analogs. They have been used to improving electronic properties for nonlinear optics through exciton transfer and molecular antenna structures for example (M. Kawa, J. M. J. Frechet, Chem. Mater. 10, 286 (1998).). We report on photoluminescence properties of star polymers with a hyperbranched core (both hyperbranched phenlyene and hyperbranched triphenylamine) and polyhexylthiophene arms. The arm is a conjugated oligomer of polythiophene that has been investigated extensively for metallic like conductivity when doped as well as utilized in field effect transistors in its undoped form (A. Tsumara, H. Koezuka, T. Ando, Appl. Phys. Lett. 49, 1210 (1986).). The cores are respectively, a nonconjugated polymer in the case of hyperbranched phenlyene and a conjugated polymer in the case of hyperbranched triphenylamine. The photoluminesce spectrum (λ_max at 575 nm) is identical for both star polymers with the two electronically different hyperbranched cores and for linear polythiophene alone. We conclude the wave functions of the core and arms do not strongly interact to form states different from their individual states and excitons formed on the hyperbranched cores migrate to the lower bandgap polythiophene before recombining.

  11. Conjugated polymer nanomaterials for theranostics

    PubMed Central

    Qian, Cheng-gen; Chen, Yu-lei; Feng, Pei-jian; Xiao, Xuan-zhong; Dong, Mei; Yu, Ji-cheng; Hu, Quan-yin; Shen, Qun-dong; Gu, Zhen

    2017-01-01

    Conjugated polymer nanomaterials (CPNs), as optically and electronically active materials, hold promise for biomedical imaging and drug delivery applications. This review highlights the recent advances in the utilization of CPNs in theranostics. Specifically, CPN-based in vivo imaging techniques, including near-infrared (NIR) imaging, two-photon (TP) imaging, photoacoustic (PA) imaging, and multimodal (MM) imaging, are introduced. Then, CPN-based photodynamic therapy (PDT) and photothermal therapy (PTT) are surveyed. A variety of stimuli-responsive CPN systems for drug delivery are also summarized, and the promising trends and translational challenges are discussed. PMID:28552910

  12. Highly selective "turn-on" fluorescent sensing of fluoride ion based on a conjugated polymer thin film-Fe(3+) complex.

    PubMed

    Ding, Wanchuan; Xu, Jingkun; Wen, Yangping; Zhang, Jie; Liu, Hongtao; Zhang, Zhouxiang

    2017-05-15

    We designed a new fluorescent conjugated polymer thin film sensor via direct electropolymerization of the corresponding electroactive monomer M onto the surface of ITO electrode, and the thin film-Fe(3+) complex was used for the highly-selective detection of fluoride ion (F(-)) in water environmental samples. The as-obtained thin film could effectively detect Fe(3+) as a selective turn-off fluorescent sensor, and exhibited outstanding reversibility. This film in the presence of Fe(3+) showed a highly selective turn-on response toward F(-) over other anions with a 5-fold enhancement in the fluorescence intensity. F(-) with a relatively wide concentration range from 10 μM to 3 mM could be determined in a rather simple and sensitive manner with a detection limit of 6.78 μM (0.128 ppm). Analytical applicability of the film-Fe(3+) complex for determining the levels of F(-) in environmental water samples has been successfully demonstrated by fluorescent analysis with satisfactory results. This strategy will provide a new approach for the facile design of new molecular sensing devices and practical application in environments.

  13. Electronic thermal conductivity, thermoelectric properties and supercapacitive behaviour of conjugated polymer nanocomposite (polyaniline-WO3) thin film

    NASA Astrophysics Data System (ADS)

    Chinedu Amaechi, Ifeanyichukwu; Nwanya, Assumpta C.; Ekwealor, Azubike B. C.; Asogwa, Paul U.; Osuji, Rose U.; Maaza, Malik; Ezema, Fabian I.

    2015-03-01

    A facile two-step, binder-free, chemical bath deposition (CBD) method was successfully employed in the synthesis of WO3 nanograins onto the matrix of conjugated polymer (polyaniline). The X-ray diffraction (XRD) results showed that the nanocomposite retained monoclinic phase of WO3 even when dispersed in polyaniline matrix. Owing to the synergistic effect offered by both the nanocomposite and structured metal oxide which may enhance the surface area, polyaniline-WO3 nanocomposite exhibited good specific capacitance. Polyaniline-WO3 yielded maximum specific capacitance ~96 F/g at scan rate of 5 mV/s in 0.5 M H2SO4 electrolyte. With the electronic thermal conductivity showing strong dependence on temperature, the estimated dimensionless figure of merit zT ~ 10-3 shows that the polymer nanocomposite (PNC) is promising as a new type of thermoelectric material. The electrochemical impedance spectroscopy showed that the PNC exhibited both pseudocapacitive and electric double layer capacitance behaviour.

  14. Processing Conjugated-Diene-Containing Polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L.; Havens, Stephen J.

    1987-01-01

    Diels-Alder reaction used to cross-linked thermoplastics. Process uses Diels-Alder reaction to cross-link and/or extend conjugated-diene-containing polymers by reacting them with bis-unsaturated dienophiles results in improved polymer properties. Quantities of diene groups required for cross-linking varies from very low to very high concentrations. Process also used to extend, or build up molecular weights of, low-molecular-weight linear polymers with terminal conjugated dienic groups.

  15. Hybrid electronics and electrochemistry with conjugated polymers.

    PubMed

    Inganäs, Olle

    2010-07-01

    In this critical review, we discuss the history and development of polymer devices wherein manipulation of the electronic conductivity by electrochemical redox processes in a conjugated polymer is used to form new functions. The devices employed are an electrochemical transistor, an electrolyte-gated field-effect transistor and light-emitting electrochemical cells, all of which combine doping/undoping of a conjugated polymer with modification of electronic transport (130 references).

  16. Quantitative electrochemical and electrochromic behavior of terthiophene and carbazole containing conjugated polymer network film precursors: EC-QCM and EC-SPR.

    PubMed

    Taranekar, Prasad; Fulghum, Timothy; Baba, Akira; Patton, Derek; Advincula, Rigoberto

    2007-01-16

    A comparative analysis of the copolymerization behavior between an electro-active terthiophene and a carbazole moiety of a conjugated polymer precursor was investigated using electrochemical and hyphenated electrochemical methods. Five different precursor polymers were first synthesized and characterized using NMR, IR, and GPC. The polymers include homopolymers of individual electro-active groups (P3T, P-CBZ) and different compositions of 25, 50, and 75% (P3TC-25, P3TC50, and P3TC-75) with respect to the two electro-active groups. Since the oxidation potentials of terthiophene and carbazole lie very close to each other, highly cross-linked copolymer films of varying extent were produced depending on the composition. The copolymerization extent was found to be dependent primarily on the amount of the terthiophene, which in this case provided for a more efficient carbazole polymerization and copolymerization than with just carbazole alone (homopolymer). The extent of copolymerization, electrochromic properties, and viscoelastic changes was quantitatively investigated using a number of hyphenated electrochemistry techniques: spectro-electrochemistry, electrochemical quartz crystal microbalance studies (EC-QCM), and electrochemical surface plasmon resonance spectroscopy (EC-SPR). Each technique revealed a unique aspect of the electrocopolymerization behavior that was used to define structure-property relationships and the deposition/copolymerization mechanism.

  17. Charge transport in highly aligned conjugated polymers (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    O'Connor, Brendan; Xue, Xiao; Sun, Tianlei

    2015-10-01

    Charge transport in conjugated polymers has a complex dependence on film morphology. Aligning the polymer chains in the plane of the film simplifies the morphology of the system allowing for insight into the morphological dependence of charge transport. Highly aligned conjugated polymers have also been shown to lead to among the highest reported field effect mobilities in these materials to date. In this talk, a comparison will be made between aligned polymer films processed using two primary methods, nanostructured substrate assisted growth and mechanical strain. A number of polymer systems including P3HT, pBTTT, N2200, and PCDTPT are considered, and the processed films are analyzed in detail with optical spectroscopy, AFM, TEM, and X-ray scattering providing insight into the molecular features that allow for effective alignment. By contrasting the morphology of these films, several insights into underlying charge transport limitations can be made. A number of key morphological features that lead to high field effect mobility and charge transport anisotropy in these films will be discussed. In addition, several unique features of organic thin film transistor device behavior in these systems will be examined including the commonly observed gate voltage dependence of saturated field effect mobility.

  18. Near-field scanning optical microscopy investigations of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Dearo, Jessie Ann

    The Near-Field Scanning Optical Microscopy (NSOM) studies of novel, optically active, conjugated polymers are presented. NSOM is a relatively new technique which produces super resolution (˜50--100 nm) optical images simultaneously with topography. The conjugated polymer poly(p-phenylene vinylene) (PPV) and derivatives of PPV are organic semiconductor-like materials with interesting and unique optical properties. Derivatives of PPV have been used in LEDs and have potential in other optoelectronic devices. NSOM provides a tool for investigation of the photoluminescence, absorption/reflection, photo-dynamics and photoconductivity of films of PPV and PPV derivatives on the length scale that these properties are fundamentally defined. The NSOM experiments have revealed mesoscale domains (˜100 nm) of varying photoluminescence emission and average molecular order in drop cast films of PPV. NSOM of stretch-oriented PPV have shown domains of perpendicular molecular orientation with low photoluminescence emission. Near-field photoconductivity experiments of stretch-oriented PPV have correlated the mesoscale topography with the photoconductivity properties of the polymer. NSOM experiments of films of poly(2-methoxy, 5-(2'-(ethyl(hexyloxy)-p-phenylene vinylene) (MEH-PPV) have shown that there is mesoscale spatial inhomogeneity in the photo-oxidation process which reduces photoluminescence emission. NSOM has also been used to create nanoscale photo-patterning in MEH-PPV films. The NSOM experiments of blended films of MEH-PPV in polystyrene have shown mesoscale phase separation directly correlated to variations in the optical properties of the film. Derivatives of PPV, stretch-oriented in polyethylene, show photoluminescence intensity variations perpendicular and parallel to the stretch-direction correlated to topography features. As a complement to the NSOM studies of conjugated polymers, single polymer molecule experiments of MEH-PPV are also presented. The

  19. Exciton transport in π-conjugated polymers with conjugation defects.

    PubMed

    Meng, Ruixuan; Li, Yuan; Li, Chong; Gao, Kun; Yin, Sun; Wang, Luxia

    2017-09-06

    In π-conjugated polymers for photovoltaic applications, intrinsic conjugation defects are known to play crucial roles in impacting exciton transport after photoexcitation. However, the understanding of the associated microscopic processes still remains limited. Here, we present a theoretical investigation of the effects of different conjugation defects on the dynamics of exciton transport in two linearly coupled poly(p-phenylene vinylene) (PPV) molecules. The model system is constructed by employing an extended version of the Su-Schrieffer-Heeger model and the exciton behaviors are simulated by means of a quantum nonadiabatic dynamics. We identify two types of conjugation defects, i.e., weakening conjugation and strengthening conjugation, which are demonstrated to play different roles in impacting the dynamics of exciton transport in the system. The weakening conjugation acts as an energy well inclined to trap a moving exciton, while the strengthening conjugation acts as an energy barrier inclined to block the exciton. We also systematically simulate both intrachain and interchain dynamics of exciton transport, and find that an exciton could experience a "short-time delaying", "trapping", "blocking", or "hopping" process, which is determined by the defect type, strength, and position. These findings provide a microscopic understanding of how the exciton transport dynamics can be impacted by conjugation defects in an actual polymer system.

  20. Microfluidic Crystal Engineering of π-Conjugated Polymers.

    PubMed

    Wang, Gang; Persson, Nils; Chu, Ping-Hsun; Kleinhenz, Nabil; Fu, Boyi; Chang, Mincheol; Deb, Nabankur; Mao, Yimin; Wang, Hongzhi; Grover, Martha A; Reichmanis, Elsa

    2015-08-25

    Very few studies have reported oriented crystallization of conjugated polymers directly in solution. Here, solution crystallization of conjugated polymers in a microfluidic system is found to produce tightly π-stacked fibers with commensurate improved charge transport characteristics. For poly(3-hexylthiophene) (P3HT) films, processing under flow caused exciton bandwidth to decrease from 140 to 25 meV, π-π stacking distance to decrease from 3.93 to 3.72 Å and hole mobility to increase from an average of 0.013 to 0.16 cm(2) V(-1) s(-1), vs films spin-coated from pristine, untreated solutions. Variation of the flow rate affected thin-film structure and properties, with an intermediate flow rate of 0.25 m s(-1) yielding the optimal π-π stacking distance and mobility. The flow process included sequential cooling followed by low-dose ultraviolet irradiation that promoted growth of conjugated polymer fibers. Image analysis coupled with mechanistic interpretation supports the supposition that "tie chains" provide for charge transport pathways between nanoaggregated structures. The "microfluidic flow enhanced semiconducting polymer crystal engineering" was also successfully applied to a representative electron transport polymer and a nonhalogenated solvent. The process can be applied as a general strategy and is expected to facilitate the fabrication of high-performance electrically active polymer devices.

  1. Continuous-wave photoinduced absorption studies in long lived photoexcitation of π-conjugated polymer and fullerene blended films

    NASA Astrophysics Data System (ADS)

    Yang, X.; Li, H.; Wang, Y. C.; Wang, R. Z.; Sheng, C.-X.

    2014-09-01

    The long lived phtoexcitation (polarons) dynamics that range from microseconds to milliseconds in a typical organic photovoltaic (OPV) material, the blends of regio-regular poly (3-hexylthiophene) (RR-P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been investigated using continuous-wave photoinduced absorption (cw-PIA) spectroscopy. In this time regime, whether above-gap (AG) or below-gap (BG) excitation, the delocalized polarons (DP) and localized polarons (LP) all exhibit dispersive bimolecular recombination process which is limited by multi-trap states; however, compared to AG, BG excitation presented the narrower distribution profile in trap polaron states. Furthermore, the recombination in RR-P3HT/PCBM films was weak temperature dependence with small thermal activation energy, the value Δ for DPs and LPs of 25 meV (45 meV) and 13 meV (42 meV) using AG (BG) excitation, respectively. We considered that polarons from BG excitation are not intrinsically different with polarons from AG one in millisecond time regime, therefore may contribute to the power conversion efficiency using appropriate materials and device structures. For completeness, cw-PIA spectroscopy of poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) and PCBM blended films with amorphous morphology were also studied. It is found that polarons also exhibited multi-trap limited bimolecular recombination, but Δ for polarons in amorphous MEH-PPV/PCBM was up to ~160 meV. We concluded that polarons in RR-P3HT/PCBM blend are basically transport by tunneling, but the recombination in MEH-PPV/PCBM blend near room temperature is mainly thermal activated process. Overall, it is demonstrated that cw-PIA spectroscopy with thermal-activated-recombination analysis can be applied to evaluate polymer (dis)order in bulk heterojunction films.

  2. Surface directed assembly of conjugated polymers for optoelectronics

    NASA Astrophysics Data System (ADS)

    Liang, Ziqi

    Conjugated polymers combining the optical and electronic properties of semiconductors with advantages of organic materials are being explored as active components in various types of thin-film electronic and optoelectronic devices. The realization of conjugated polymer based electronics and optoelectronics critically depends on developing novel approaches for assembling this new class of materials into a controlled fashion. We have developed new non-photolithographic methods for the spatial deposition of conjugated polymers. As a proof-of-concept of these methods, the well-known luminescent polymer, poly(p-phenylene vinylene) (PPV), has been used as a model structure in our work. One strategy is based on the modification of solid substrates with microcontact-printed self-assembled monolayers (SAMs) that serve as templates for the deposition of PPVs from solution. Conjugated polymer patterns have also been generated by directly stamping of PPVs onto the reactive SAMs-coated substrates. In both methods, PPVs were covalently immobilized onto the supporting surface through the formation of amide bonds, thus rendering great stability of the resulting patterns. Well-defined PPV micropatterns have been fully characterized by UV-vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and fluorescence optical microscopy. The interaction between PPVs and the underlying surface was analyzed by grazing-angle reflectance Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Many applications based on conjugated polymers require the controlled assembly of the polymers as multilayer structures, in which molecules with different functionality can be incorporated into individual layers with precisely controlled thickness. We have developed a series of layer-by-layer (LbL) assembly approaches to multilayer conjugated polymer thin films. Hydrogen-bonding interaction and covalent coupling reaction have been utilized

  3. Conjugation Length Distribution in Poly(p-phenylenevinylene) (PPV) Films.

    PubMed

    da Silva, Marcelo C; Cassemiro, Sandra de M; Machado, Angelita M; Alves, Joniel C F; Nogueira, Sandra L; Jarrosson, Thibault; Serein-Spirau, Françoise; Akcelrud, Leni; Tozoni, José R; Silva, Raigna A; Freire, José A; Marletta, Alexandre

    2016-12-15

    We studied the absorption line-shape of poly(p-phenylenevinylene) (PPV) films deposited via spin coating and Langmuir-Blodgett techniques with the intent of identifying the conjugation length distribution in these two types of films, a key morphological aspect of conjugated polymer films. We treated the excitons in the polymer as independent oligomer excitons and modeled the absorption spectra of the individual oligomers using simple expressions for the oligomer size dependence of the gap energy, the line-broadening factor, the transition dipole moment and the Huang-Rhys parameter. We validated these expressions by independent measurements on phenyl-based oligomers and Density Functional Theory calculations. Our results show clear evidence that, for both types of PPV films, the conjugation length distribution depends exponentially on the segment size. Our results also set a lower limit, of about ten repeat units, for the maximum exciton length of three different phenyl-based oligomers.

  4. Conjugated amplifying polymers for optical sensing applications.

    PubMed

    Rochat, Sébastien; Swager, Timothy M

    2013-06-12

    Thanks to their unique optical and electrochemical properties, conjugated polymers have attracted considerable attention over the last two decades and resulted in numerous technological innovations. In particular, their implementation in sensing schemes and devices was widely investigated and produced a multitude of sensory systems and transduction mechanisms. Conjugated polymers possess numerous attractive features that make them particularly suitable for a broad variety of sensing tasks. They display sensory signal amplification (compared to their small-molecule counterparts) and their structures can easily be tailored to adjust solubility, absorption/emission wavelengths, energy offsets for excited state electron transfer, and/or for use in solution or in the solid state. This versatility has made conjugated polymers a fluorescence sensory platform of choice in the recent years. In this review, we highlight a variety of conjugated polymer-based sensory mechanisms together with selected examples from the recent literature.

  5. High-Performing Thin-Film Transistors in Large Spherulites of Conjugated Polymer Formed by Epitaxial Growth on Removable Organic Crystalline Templates.

    PubMed

    Kim, Jae Yoon; Yang, Da Seul; Shin, Jicheol; Bilby, David; Chung, Kyeongwoon; Um, Hyun Ah; Chun, Jaehee; Pyo, Seungmoon; Cho, Min Ju; Kim, Jinsang; Choi, Dong Hoon

    2015-06-24

    Diketopyrrolopyrrole (DPP)-based conjugated polymer PDTDPPQT was synthesized and was used to perform epitaxial polymer crystal growth on removable 1,3,5-trichlorobenzene crystallite templates. A thin-film transistor (TFT) was successfully fabricated in well-grown large spherulites of PDTDPPQT. The charge carrier mobility along the radial direction of the spherulites was measured to be 5.46-12.04 cm(2) V(-1) s(-1), which is significantly higher than that in the direction perpendicular to the radial direction. The dynamic response of charge transport was also investigated by applying a pulsed bias to TFTs loaded with a resistor (∼20 MΩ). The charge-transport behaviors along the radial direction and perpendicular to the radial direction were investigated by static and dynamic experiments through a resistor-loaded (RL) inverter. The RL inverter made of PDTDPPQT-based TFT operates well, maintaining a fairly high switching voltage ratio (Vout(ON)/Vout(OFF)) at a relatively high frequency when the source-drain electrodes are aligned parallel to the radial direction.

  6. Compatibilization of All-Conjugated Polymer Blends for Organic Photovoltaics.

    PubMed

    Lombeck, Florian; Sepe, Alessandro; Thomann, Ralf; Friend, Richard H; Sommer, Michael

    2016-08-23

    Compatibilization of an immiscible binary blend comprising a conjugated electron donor and a conjugated electron acceptor polymer with suitable electronic properties upon addition of a block copolymer (BCP) composed of the same building blocks is demonstrated. Efficient compatibilization during melt-annealing is feasible when the two polymers are immiscible in the melt, i.e. above the melting point of ∼250 °C of the semicrystalline donor polymer P3HT. To generate immiscibility at these high temperatures, the acceptor polymer PCDTBT is equipped with fluorinated side chains leading to an increased Flory-Huggins interaction parameter. Compatibilization in bulk and thin films is demonstrated, showing that the photovoltaic performance of pristine microphase separated and nanostructured BCPs can also be obtained for compatibilized blend films containing low contents of 10-20 wt % BCP. Thermodynamically stable domain sizes range between several tens of microns for pure blends and ∼10 nm for pure block copolymers. In addition to controlling domain size, the amount of block copolymer added dictates the ratio of edge-on and face-on P3HT crystals, with compatibilized films showing an increasing amount of face-on P3HT crystals with increasing amount of compatibilizer. This study demonstrates the prerequisites and benefits of compatibilizing all-conjugated semicrystalline polymer blends for organic photovoltaics.

  7. Spectroscopy on Conjugated Polymer Devices

    NASA Astrophysics Data System (ADS)

    Dyakonov, Vladimir

    The following sections are included: * INTRODUCTION * EXPERIMENTAL * Sample Preparation * Experimental Set-up * Frequency Resolved ODMR * RESULTS * Studies on the Recombination and Transport in the Polymer Devices via Measurements of the Photoinduced Current and the Electroluminescence * ESR Detected via Photoinduced Current * Magnetic Field Effect on the Photocurrent * ESR Detected via Electroluminescence Intensity * Photoluminescence Studies on Films of PPV and PPPV * Changes of the Photoluminescence Intensity under Conditions of ESR * Dependence of the ODMR on the Excitation Intensity and the Temperature * Spectral Dependence of ODMR * Studies of the recombination kinetics by means of frequency resolved ODMR * The Influence of the Thermal Conversion of PPV on the ODMR Intensity * DISCUSSION * On the Nature of the States Participating in Photocurrent Detected Magnetic Resonance * Excitations Participating in Electroluminescence Detected Magnetic Resonance * Evidences for Photoinduced Inter-Chain Triplet Polaron Pairs and Their Transformations In PPV * Triplet Excitons Annihilation as Origin of the Delayed Photoluminescence * Kinetic Connection Between Magnetic Resonant Transitions and Photo-Luminescence Intensity * Dependence of the Magnitude of the Resonant Signals on the Light Intensity * Dependence of the Magnitude of the Resonant Signals on the Frequency of Microwave Power Modulation * On the Polarisation of Triplet Excitons * Temperature Dependence of the ODMR Intensity * The Influence of the Thermal Conversion of the Prepolymer on Recombination Processes * Remarks on the Previous Recombination Models in Magnetic Resonance Experiments * CONCLUSION * Acknowledgements * REFERENCES

  8. Direct probing of a polymer electrolyte/luminescent conjugated polymer mixed ionic/electronic conductor.

    PubMed

    Hu, Yufeng; Gao, Jun

    2009-12-30

    What will happen if one brings two metallic probes into direct contact with a polymer film and apply a voltage bias? We demonstrate that, for a mixed ionic/electronic conductor containing a luminescent conjugated polymer and a polymer electrolyte, it is possible to induce strong in situ electrochemical doping of the luminescent polymer and form a dynamic light-emitting p-n junction. Using time-lapse fluorescence imaging, we have visualized p- and n-doping of various shapes and shades, p-n junction electroluminescence, and the effects of voltage reversal. The direct probing technique offers great simplicity and versatility for studying luminescent mixed ionic/electronic conductors.

  9. Donor-acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy.

    PubMed

    Chaudhari, Sachin R; Griffin, John M; Broch, Katharina; Lesage, Anne; Lemaur, Vincent; Dudenko, Dmytro; Olivier, Yoann; Sirringhaus, Henning; Emsley, Lyndon; Grey, Clare P

    2017-04-01

    Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor-acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT). Using conventional (1)H and (13)C solid-state MAS NMR coupled with density functional theory calculations and molecular dynamics simulations, we find that the bulk polymer adopts a highly planar backbone conformation with a laterally-shifted donor-on-acceptor stacking arrangement. DNP SENS enables acquisition of (13)C NMR data for polymer films, where sensitivity is limiting owing to small sample volumes. The DNP signal enhancement enables a two-dimensional (1)H-(13)C HETCOR spectrum to be recorded for a drop-cast polymer film, and a (13)C CPMAS NMR spectrum to be recorded for a spin-coated thin-film with a thickness of only 400 nm. The results show that the same planar backbone structure and intermolecular stacking arrangement is preserved in the films following solution processing and annealing, thereby rationalizing the favourable device properties of DPP-DTT, and providing a protocol for the study of other thin film materials.

  10. Conjugated polymer/molten salt blend optimization.

    PubMed

    Habrard, F; Ouisse, T; Stéphan, O

    2006-08-10

    Light-emitting electrochemical cells with low current threshold can be realized through mixing conjugated polymers and molten salts. Current drive capability is proportional to the overall interface perimeter of the planar, discotic molten salt domains inserted into the polymer matrix. Electric force microscopy indicates that this interface perimeter exhibits a specific dependence on the molten salt content in the active layer, with a well-defined maximum. We show that this maximum corresponds to an optimal current drive.

  11. Rapid Energy Transfer and Improved Performance of Organic Light-Emitting Diodes Using Composite Film Based on π-Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Yamasaki, Naoyuki; Watanabe, Masahiko; Masuyama, Kimihiro; Miyake, Yasuo; Kubo, Hitoshi; Fujii, Akihiko; Ozaki, Masanori

    2009-10-01

    The optical and electrical properties of polymer composite films based on poly(2-methoxy-5-dodecyloxy-p-phenylenevinylene) (MDDOPPV) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) have been studied. We investigated the time-resolved photoluminescence of the composite films and clarified the rapid intermolecular energy transfer from F8BT to MDDOPPV. As a result of the utilization of the polymer composite thin film as the emission layer of a light-emitting diode, a 23-fold increase in luminance was observed in comparison to that with a non composite MDDOPPV emission layer.

  12. Electrochemical Sensors Based on Organic Conjugated Polymers

    PubMed Central

    Rahman, Md. Aminur; Kumar, Pankaj; Park, Deog-Su; Shim, Yoon-Bo

    2008-01-01

    Organic conjugated polymers (conducting polymers) have emerged as potential candidates for electrochemical sensors. Due to their straightforward preparation methods, unique properties, and stability in air, conducting polymers have been applied to energy storage, electrochemical devices, memory devices, chemical sensors, and electrocatalysts. Conducting polymers are also known to be compatible with biological molecules in a neutral aqueous solution. Thus, these are extensively used in the fabrication of accurate, fast, and inexpensive devices, such as biosensors and chemical sensors in the medical diagnostic laboratories. Conducting polymer-based electrochemical sensors and biosensors play an important role in the improvement of public health and environment because rapid detection, high sensitivity, small size, and specificity are achievable for environmental monitoring and clinical diagnostics. In this review, we summarized the recent advances in conducting polymer-based electrochemical sensors, which covers chemical sensors (potentiometric, voltammetric, amperometric) and biosensors (enzyme based biosensors, immunosensors, DNA sensors). PMID:27879698

  13. Effect of Broken Conjugation on the Stretchability of Semiconducting Polymers.

    PubMed

    Savagatrup, Suchol; Zhao, Xikang; Chan, Esther; Mei, Jianguo; Lipomi, Darren J

    2016-10-01

    Increasing the flexibility of polymer chains is a common method of increasing the deformability of solid polymeric materials. Here, the effects of "conjugation-break spacers" (CBSs)-aliphatic units that interrupt the sp(2) -hybridized backbone of semiconducting polymers-on the mechanical and photovoltaic properties of a diketopyrrolopyrrole-based polymer are described. Unexpectedly, the tensile moduli and cracking behavior of a series of polymers with repeat units bearing 0%, 30%, 50%, 70%, and 100% of the CBS are not directly related to the percent incorporation of the flexible unit. Rather, the mechanical properties are a strong function of the order present in the film as determined by grazing-incidence x-ray diffraction. The effect of the CBSs on the photovoltaic performance of these materials, on the other hand, is more intuitive: it decreases with increasing fraction of the flexible units. These studies highlight the importance of solid-state packing structure-as opposed to only the flexibility of the individual molecules-in determining the mechanical properties of a conjugated polymer film for stretchable, ultraflexible, and mechanically robust electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Novel conjugates of peptides and conjugated polymers for optoelectronics and neural interfaces

    NASA Astrophysics Data System (ADS)

    Bhagwat, Nandita

    Peptide-polymer conjugates are a novel class of hybrid materials that take advantage of each individual component giving the opportunity to generate materials with unique physical, chemical, mechanical, optical, and electronic properties. In this dissertation peptide-polymer conjugates for two different applications are discussed. The first set of peptide-polymer conjugates were developed as templates to study the intermolecular interactions between electroactive molecules by manipulating the intermolecular distances at nano-scale level. A PEGylated, alpha-helical peptide template was employed to effectively display an array of organic chromophores (oxadiazole containing phenylenevinylene oligomers, Oxa-PPV). Three Oxa-PPV chromophores were strategically positioned on each template, at distances ranging from 6 to 17 A from each other, as dictated by the chemical and structural properties of the peptide. The Oxa-PPV modified PEGylated helical peptides (produced via Heck coupling strategies) were characterized by a variety of spectroscopic methods. Electronic contributions from multiple pairs of chromophores on a scaffold were detectable; the number and relative positioning of the chromophores dictated the absorbance and emission maxima, thus confirming the utility of these polymer--peptide templates for complex presentation of organic chromophores. The rest of the thesis is focused on using poly(3,4-alkylenedioxythiophene) based conjugated polymers as coatings for neural electrodes. This thiophene derivative is of considerable current interest for functionalizing the surfaces of a wide variety of devices including implantable biomedical electronics, specifically neural bio-electrodes. Toward these ends, copolymer films of 3,4-ethylenedioxythiophene (EDOT) with a carboxylic acid functional EDOT (EDOTacid) were electrochemically deposited and characterized as a systematic function of the EDOTacid content (0, 25, 50, 75, and 100%). The chemical surface characterization

  15. Conjugated polymer networks: Synthesis and properties

    NASA Astrophysics Data System (ADS)

    Kokil, Akshay

    The experimental research program that forms the basis of this thesis has been directed towards the design, synthesis, processing and physical characterization of well-defined conjugated polymer networks. It attempts to provide answers to the questions how such materials can be synthesized and processed and how the introduction of cross-links can be exploited for the creation of polymeric materials with optimized optic and electronic characteristics. Interestingly, this family of materials has received little attention in the past, at least as far as systematic studies of well-defined systems are concerned. This situation may be a direct consequence of the challenge to introduce conjugated cross-links into conjugated polymers and retain adequate processibility. We have shown that organometallic polymer networks based on linear conjugated polymers are readily accessible through ligand-exchange reactions. This approach was exemplified by exploiting the ethynyl moieties comprised in poly( p-phenylene ethynylene) (PPE) derivatives as ligand sites, which allow for complexation with selected metals and cross-linking via the resulting PPE-Metal complexes. Focusing on the dinuclear complex [Pt-(mu-Cl)Cl-PPE] 2 and PPE-Pt0 as crosslinks, we have conducted an in-depth investigation on how the nature of the metal cross-links influences the materials characteristics, in particular the charge transport properties. We first investigated the charge carrier mobility of poly[2,5-dioctyloxy-1,4-diethynyl-phenylene- alt-2,5-bis(2'-ethylhexyloxy)-1,4-phenylene] (EHO-OPPE), as a classic representative of poly(p-phenylene ethynylene) (PPE) derivatives, which represent an important class of conjugated polymers. In what appears to be the first study ever conducted on the mobility of any PPE, we found that EHO-OPPE displays ambipolar charge transport characteristics with very high electron (1.9·10-3 cm2V-1 s-1) and hole (1.6·10-3 cm 2V-1s-1) mobilities. Most importantly, the introduction

  16. Excitons in conjugated polymers from first principles

    NASA Astrophysics Data System (ADS)

    van der Horst, J.-W.; Bobbert, P. A.; Pasveer, W. F.; Michels, M. A. J.; Brocks, G.; Kelly, P. J.

    2002-08-01

    By a combination of ab-initio computational techniques, based on density-functional theory, GW theory, and the Bethe-Salpeter equation, we study the opto-electronic properties of several conjugated polymers and in particular the properties of excitons. We study three different situations: (I) an isolated polymer chain, (II) a chain embedded in a dielectric medium, and (III) a polymer crystal. Surprisingly, the results obtained for situation (II) generally agree best with experiment. We discuss possible reasons for this rule and an interesting exception.

  17. Band bending in conjugated polymer layers.

    PubMed

    Lange, Ilja; Blakesley, James C; Frisch, Johannes; Vollmer, Antje; Koch, Norbert; Neher, Dieter

    2011-05-27

    We use the Kelvin probe method to study the energy-level alignment of four conjugated polymers deposited on various electrodes. Band bending is observed in all polymers when the substrate work function exceeds critical values. Through modeling, we show that the band bending is explained by charge transfer from the electrodes into a small density of states that extends several hundred meV into the band gap. The energetic spread of these states is correlated with charge-carrier mobilities, suggesting that the same states also govern charge transport in the bulk of these polymers. © 2011 American Physical Society

  18. Conjugated Polymers Atypically Prepared in Water

    PubMed Central

    Invernale, Michael A.; Pendergraph, Samuel A.; Yavuz, Mustafa S.; Ombaba, Matthew; Sotzing, Gregory A.

    2010-01-01

    Processability remains a fundamental issue for the implementation of conducting polymer technology. A simple synthetic route towards processable precursors to conducting polymers (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties. PMID:20959869

  19. Ultrafast Relaxation in Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takayoshi

    The following sections are included: * INTRODUCTION * EXPERIMENTAL * Samples * Femtosecond experimental apparatus * RESULTS AND DISCUSSION * Poly(phenylacetylenes) * Blue-phase PDA-3BCMU * Red-phase PDA-4BCMU * Blue-phase PDA-DFMP * P3MT * P3DT * PTV * RELAXATION MECHANISMS * Review of the previous works * Symmetry of the lower electronic excited states * Primary relaxation processes * Theoretical studies of nonlinear excitations * Mechanism of relaxation in polymers with a weakly nondegenerate ground state (poly(phenylacetylene)s) * Dual peak component with power-law decay * Single-peak component with an exponential decay * Hot self-trapped exciton * Transition to the electron-hole threshold * Transition to a biexciton state * Mechanism of relaxation in polymers with a strongly or moderately nondegenerate ground state * Classifications of polymers * Femtosecond relaxation * Picosecond relaxation * CONCLUSION * Acknowledgments * REFERENCES

  20. Solvent immersion nanoimprint lithography of fluorescent conjugated polymers

    NASA Astrophysics Data System (ADS)

    Whitworth, G. L.; Zhang, S.; Stevenson, J. R. Y.; Ebenhoch, B.; Samuel, I. D. W.; Turnbull, G. A.

    2015-10-01

    Solvent immersion imprint lithography (SIIL) was used to directly nanostructure conjugated polymer films. The technique was used to create light-emitting diffractive optical elements and organic semiconductor lasers. Gratings with lateral features as small as 70 nm and depths of ˜25 nm were achieved in poly(9,9-dioctylfluorenyl-2,7-diyl). The angular emission from the patterned films was studied, comparing measurement to theoretical predictions. Organic distributed feedback lasers fabricated with SIIL exhibited thresholds for lasing of ˜40 kW/cm2, similar to those made with established nanoimprint processes. The results show that SIIL is a quick, convenient and practical technique for nanopatterning of polymer photonic devices.

  1. Crosslinked polymer nanoparticles containing single conjugated polymer chains

    NASA Astrophysics Data System (ADS)

    Ponzio, Rodrigo A.; Marcato, Yésica L.; Gómez, María L.; Waiman, Carolina V.; Chesta, Carlos A.; E Palacios, Rodrigo

    2017-06-01

    Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

  2. Crosslinked polymer nanoparticles containing single conjugated polymer chains.

    PubMed

    Ponzio, Rodrigo A; Marcato, Yésica L; Gómez, María L; Waiman, Carolina V; Chesta, Carlos A; Palacios, Rodrigo E

    2017-03-29

    Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

  3. Photoluminescence quenching of conjugated polymer nanocomposites for gamma ray detection

    NASA Astrophysics Data System (ADS)

    Zhong, Haizheng; Zhao, Yong Sheng; Li, Yongfang; Pei, Qibing

    2008-12-01

    The high atomic number of bismuth iodide and the high-sensitivity photoluminescence quenching of conjugated polymers are leveraged in their nanocomposites for the detection of high-energy photons. With the introduction of oleylamine, the composites can be processed from solutions in organic solvent into high-quality films containing as much as 50 wt% BiI3. BiI3 in the resulting ternary composites is dispersed on a nanoscale or smaller, allowing the formation of transparent composites. Oleylamine was found to form an interfacial layer between the polymer matrix and BiI3 nanodomains to block charge transfer between BiI3 and the polymer. Upon gamma ray exposure, the luminescent intensity of the ternary composites decreased linearly with the radiation dosage.

  4. Highly Sensitive Thin-Film Field-Effect Transistor Sensor for Ammonia with the DPP-Bithiophene Conjugated Polymer Entailing Thermally Cleavable tert-Butoxy Groups in the Side Chains.

    PubMed

    Yang, Yang; Zhang, Guanxin; Luo, Hewei; Yao, Jingjing; Liu, Zitong; Zhang, Deqing

    2016-02-17

    The sensing and detection of ammonia have received increasing attention in recent years because of the growing emphasis on environmental and health issues. In this paper, we report a thin-film field-effect transistor (FET)-based sensor for ammonia and other amines with remarkable high sensitivity and satisfactory selectivity by employing the DPP-bithiophene conjugated polymer pDPPBu-BT in which tert-butoxycarboxyl groups are incorporated in the side chains. This polymer thin film shows p-type semiconducting property. On the basis of TGA and FT-IR analysis, tert-butoxycarboxyl groups can be transformed into the -COOH ones by eliminating gaseous isobutylene after thermal annealing of pDPPBu-BT thin film at 240 °C. The FET with the thermally treated thin film of pDPPBu-BT displays remarkably sensitive and selective response toward ammonia and volatile amines. This can be attributed to the fact that the elimination of gaseous isobutylene accompanies the formation of nanopores with the thin film, which will facilitate the diffusion and interaction of ammonia and other amines with the semiconducting layer, leading to high sensitivity and fast response for this FET sensor. This FET sensor can detect ammonia down to 10 ppb and the interferences from other volatile analytes except amines can be negligible.

  5. Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor-Acceptor Conjugated Polymers.

    PubMed

    Ayzner, Alexander L; Mei, Jianguo; Appleton, Anthony; DeLongchamp, Dean; Nardes, Alexandre; Benight, Stephanie; Kopidakis, Nikos; Toney, Michael F; Bao, Zhenan

    2015-12-30

    Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

  6. Electronic properties of sulfur containing conjugated polymers

    NASA Astrophysics Data System (ADS)

    Brédas, J. L.; Elsenbaumer, R. L.; Chance, R. R.; Silbey, Robert

    1983-05-01

    Valence effective Hamiltonian (VEH) calculations are performed on a number of sulfur containing organic conjugated polymers of interest to the conducting polymers area. Theoretical results for parameters related to conductivity such as ionization potentials, bandwidths, and bandgaps are presented. Systems considered include various derivatives of poly (p-phenylene sulfide), polybenzothiophene, and polythiophene, as well as potentially interesting compounds such as polythieno [3,2-b] thiophene and polyvinylene sulfide. The electronic structure description afforded by the VEH method for sulfur containing polymers is demonstrated to be of the same quality as that presented previously for hydrocarbon polymers. In particular, for ionization potentials, good agreement with available experimental data on poly (p-phenylene sulfide) and polybenzothiophene is obtained, after scaling downward the VEH values by a 1.9 eV polarization correction. The comparison between the theoretical and experimental XPS spectra for polybenzothiophene is excellent with use of the same energy scaling factor previously employed for polyacetylene, poly(p-phenylene), and poly(p-phenylene sulfide). These results, in conjuction with previous results obtained on hydrocarbon polymers, lend confidence in the predictive capabilities of this purely theoretical technique. Calculations show that polyvinylene sulfide, as yet unsynthesized, should display very promising characteristics as a conducting polymer.

  7. Overcoming Film Quality Issues for Conjugated Polymers Doped with F4TCNQ by Solution Sequential Processing: Hall Effect, Structural, and Optical Measurements.

    PubMed

    Scholes, D Tyler; Hawks, Steven A; Yee, Patrick Y; Wu, Hao; Lindemuth, Jeffrey R; Tolbert, Sarah H; Schwartz, Benjamin J

    2015-12-03

    We demonstrate that solution-sequential processing (SqP) can yield heavily doped pristine-quality films when used to infiltrate the molecular dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) into pure poly(3-hexylthiophene) (P3HT) polymer layers. Profilometry measurements show that the SqP method produces doped films with essentially the same surface roughness as pristine films, and 2-D grazing-incidence wide-angle X-ray scattering (GIWAXS) confirms that SqP preserves both the size and orientation of the pristine polymer's crystallites. Unlike traditional blend-cast F4TCNQ/P3HT doped films, our sequentially processed layers have tunable and reproducible conductivities reaching as high as 5.5 S/cm even when measured over macroscopic (>1 cm) distances. The high conductivity and superb film quality allow for meaningful Hall effect measurements, which reveal p-type conduction and carrier concentrations tunable from 10(16) to 10(20) cm(-3) and hole mobilities ranging from ∼0.003 to 0.02 cm(2) V(-1) s(-1) at room temperature over the doping levels examined.

  8. A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics.

    PubMed

    Kim, Bong-Gi; Jeong, Eun Jeong; Chung, Jong Won; Seo, Sungbaek; Koo, Bonwon; Kim, Jinsang

    2013-07-01

    Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur-fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.

  9. A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics

    NASA Astrophysics Data System (ADS)

    Kim, Bong-Gi; Jeong, Eun Jeong; Chung, Jong Won; Seo, Sungbaek; Koo, Bonwon; Kim, Jinsang

    2013-07-01

    Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur-fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.

  10. Controlling the Surface Organization of Conjugated Donor-Acceptor Polymers by their Aggregation in Solution.

    PubMed

    Li, Mengmeng; An, Cunbin; Marszalek, Tomasz; Baumgarten, Martin; Yan, He; Müllen, Klaus; Pisula, Wojciech

    2016-11-01

    The aggregation of conjugated polymers is found to have a significant influence on the surface organization of deposited films. Difluorobenzothiadiazole-based polymers show a strong pre-aggregation in solution, but the addition of 1,2,4-trichlorobenzene efficiently reduces such aggregates, leading to the transition of the surface organization from edge- to face-on orientation in deposited films. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Antistaphylococcal Nanocomposite Films Based on Enzyme-Nanotube Conjugates

    PubMed Central

    Pangule, Ravindra C.; Brooks, Sarah J.; Dinu, Cerasela Zoica; Bale, Shyam Sundhar; Salmon, Sharon L.; Zhu, Guangyu; Metzger, Dennis W.; Kane, Ravi S.; Dordick, Jonathan S.

    2010-01-01

    Infection with antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is one of the primary causes of hospitalizations and deaths. To address this issue, we have designed antimicrobial coatings incorporating carbon nanotube-enzyme conjugates that are highly effective against antibiotic–resistant pathogens. Specifically, we incorporated conjugates of carbon nanotubes with lysostaphin, a cell wall degrading enzyme, into films to impart bactericidal properties against Staphylococcus aureus and Staphylococcus epidermidis. We fabricated and characterized nanocomposites containing different conjugate formulations and enzyme loadings. These enzyme–based composites were highly efficient in killing MRSA (>99% within 2 h) without release of the enzyme into solution. Additionally, these films were reusable and stable under dry storage conditions for a month. Such enzyme–based film formulations may be used to prevent growth of pathogenic and antibiotic-resistant microorganisms on various common surfaces in hospital settings. Polymer and paint films containing such antimicrobial conjugates, in particular, could be advantageous to prevent risk of staphylococcal-specific infection and biofouling. PMID:20604574

  12. Antistaphylococcal nanocomposite films based on enzyme-nanotube conjugates.

    PubMed

    Pangule, Ravindra C; Brooks, Sarah J; Dinu, Cerasela Zoica; Bale, Shyam Sundhar; Salmon, Sharon L; Zhu, Guangyu; Metzger, Dennis W; Kane, Ravi S; Dordick, Jonathan S

    2010-07-27

    Infection with antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is one of the primary causes of hospitalizations and deaths. To address this issue, we have designed antimicrobial coatings incorporating carbon nanotube-enzyme conjugates that are highly effective against antibiotic-resistant pathogens. Specifically, we incorporated conjugates of carbon nanotubes with lysostaphin, a cell wall degrading enzyme, into films to impart bactericidal properties against Staphylococcus aureus and Staphylococcus epidermidis. We fabricated and characterized nanocomposites containing different conjugate formulations and enzyme loadings. These enzyme-based composites were highly efficient in killing MRSA (>99% within 2 h) without release of the enzyme into solution. Additionally, these films were reusable and stable under dry storage conditions for a month. Such enzyme-based film formulations may be used to prevent growth of pathogenic and antibiotic-resistant microorganisms on various common surfaces in hospital settings. Polymer and paint films containing such antimicrobial conjugates, in particular, could be advantageous to prevent risk of staphylococcal-specific infection and biofouling.

  13. Design, synthesis, characterization and study of novel conjugated polymers

    SciTech Connect

    Chen, Wu

    1997-06-24

    After introducing the subject of conjugated polymers, the thesis has three sections each containing a literature survey, results and discussion, conclusions, and experimental methods on the following: synthesis, characterization of electroluminescent polymers containing conjugated aryl, olefinic, thiophene and acetylenic units and their studies for use in light-emitting diodes; synthesis, characterization and study of conjugated polymers containing silole unit in the main chain; and synthesis, characterization and study of silicon-bridged and butadiene-linked polythiophenes.

  14. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers

    PubMed Central

    Xu, Lai; Li, Youyong

    2016-01-01

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers. PMID:27356483

  15. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

    PubMed

    Xu, Lai; Li, Youyong

    2016-06-30

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers.

  16. Conjugated polymer sensors built on pi-extended borasiloxane cages.

    PubMed

    Liu, Wenjun; Pink, Maren; Lee, Dongwhan

    2009-06-24

    An efficient 2 + 2 cyclocondensation with dihydroxysilane converted simple arylboronic acids to bifunctional borasiloxane cage molecules, which were subsequently electropolymerized to furnish air-stable thin films. The extended [p,pi]-conjugation that defines the rigid backbone of this new conjugated polymer (CP) motif gives rise to longer-wavelength UV-vis transitions upon oxidative doping, the spectral window and intensity of which can be modified by interaction with Lewis basic reagents. Notably, this boron-containing CP undergoes a rapid and reversible color change from green to orange upon exposure to volatile amine samples under ambient conditions. This direct naked-eye detection scheme can best be explained by invoking the reversible B-N dative bond formation that profoundly influences the p-pi* orbital overlap.

  17. Oxygen-dependent hologram writing and fixing in conjugated polymer storage media

    NASA Astrophysics Data System (ADS)

    Levi, Ofer; Agranat, Aharon J.; Perepelitsa, Galina; Shalom, Shoshy; Neumann, Ronny; Avny, Yair; Davidov, Dan

    1999-11-01

    Hologram writing and fixing mechanisms are examined in disordered conjugated polymer/glass composites. The conjugated polymers used were alkoxy substituted poly(phenylenevinylne) analogs and the glass matrices were zirconia-organosilica xerogels. Hologram formation mechanism is shown to be a photochromic process consisting of light induced photo- oxidation (bleaching) of the embedded conjugated polymer resulting in the formation of an absorption grating and a phase grating. IR and Raman spectroscopy show that the chemical transformations upon photo-bleaching involve chain scission and oxidation of the polymer at the vinylic position of the conjugated polymer. Oxygen removal increases hologram formation time by more than an order of magnitude and halves the total hologram efficiency. The oxygen dependence was also highly correlated with photo-bleaching of the samples and beam interaction of the writing beams. Light sensitivity was compared for several polymer/glass composites showing that the new composites and film preparation techniques are promising for blue and ultraviolet sensitive holographic materials. A hologram fixing method based on a PMMA coating, applied on the film after hologram formation is demonstrated and shown to increase hologram erasure times by four. These important findings show that conjugated polymer/glass composites based storage media can be manufactured and fixed efficiently for a long term based on this method.

  18. Dewetting of Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Dixit, P. S.; Sorensen, J. L.; Kent, M.; Jeon, H. S.

    2001-03-01

    DEWETTING OF THIN POLYMER FILMS P. S. Dixit,(1) J. L. Sorensen,(2) M. Kent,(2) H. S. Jeon*(1) (1) Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, jeon@nmt.edu (2) Department 1832, Sandia National Laboratories, Albuquerque, NM. Dewetting of thin polymer films is of technological importance for a variety of applications such as protective coatings, dielectric layers, and adhesives. Stable and smooth films are required for the above applications. Above the glass transition temperature (Tg) the instability of polymer thin films on a nonwettable substrate can be occurred. The dewetting mechanism and structure of polypropylene (Tg = -20 ^circC) and polystyrene (Tg = 100 ^circC) thin films is investigated as a function of film thickness (25 Åh < 250 Åand quenching temperature. Contact angle measurements are used in conjunction with optical microscope to check the surface homogeneity of the films. Uniform thin films are prepared by spin casting the polymer solutions onto silicon substrates with different contact angles. We found that the stable and unstable regions of the thin films as a function of the film thickness and quenching temperature, and then constructed a stability diagram for the dewetting of thin polymer films. We also found that the dewetting patterns of the thin films are affected substantially by the changes of film thickness and quenching temperature.

  19. Thin films of photoactive polymer blends.

    PubMed

    Ruderer, Matthias A; Metwalli, Ezzeldin; Wang, Weinan; Kaune, Gunar; Roth, Stephan V; Müller-Buschbaum, Peter

    2009-03-09

    The morphology inside photoactive blended films of two conjugated homopolymers poly [(1-methoxy)-4-(2-ethylhexyloxy)-p-phenylene-vinylene] (MEH-PPV) and poly(3-hexylthiophene-2,5-diyl) (P3HT) is investigated. For both homopolymers a linear dependence of the installed film thickness from the concentration of the polymer solution used in spin coating is probed. This dependence allows preparation of an efficient series of blended films with constant thickness and different blending ratios. Information about the lateral structure inside the films is gained from grazing incidence small angle X-ray scattering. At the calculated critical blending ratio the smallest lateral separation between adjacent domains is found representing the highest surface contact between both homopolymers in the films. The presence of wetting layers at both interfaces as detected with X-ray reflectivity and atomic force microscopy is promising for photovoltaic applications. UV/Vis spectroscopy complements the structural investigation.

  20. Fluoro-Substituted n-Type Conjugated Polymers for Additive-Free All-Polymer Bulk Heterojunction Solar Cells with High Power Conversion Efficiency of 6.71.

    PubMed

    Jung, Jae Woong; Jo, Jea Woong; Chueh, Chu-Chen; Liu, Feng; Jo, Won Ho; Russell, Thomas P; Jen, Alex K-Y

    2015-06-03

    Fluorinated n-type conjugated polymers are used as efficient electron acceptor to demonstrate high-performance all-polymer solar cells. The exciton generation, dissociation, and charge-transporting properties of blend films are improved by using these fluorinated n-type polymers to result in enhanced photocurrent and suppressed charge recombination.

  1. Polymer--drug conjugates as nano-sized medicines.

    PubMed

    Canal, Fabiana; Sanchis, Joaquin; Vicent, María J

    2011-12-01

    Polymer Therapeutics have enormously evolved in the past decades. Several polymeric drugs as well as polymer-protein conjugates have been in the market since the 90s, but although polymer-drug conjugates are already in clinical trials they still need to reach this final goal. There are four main convergent strategies to move this platform technology further. First, exploitation of new molecular targets in cancer therapy and design of polymer-drug conjugates as treatments for other diseases. Second, the development of combination therapy. Third, attempts to improve polymer chemistry, including the use of new well-defined architectures and the optimization of the advanced characterization techniques essential to transform a promising conjugate into a candidate for clinical evaluation. Finally, increased understanding of polymer conjugate features that govern clinical risk-benefit is leading to an appreciation of clinical biomarkers that will open new possibilities for personalized therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Controlling Molecular Ordering in Solution-State Conjugated Polymers

    SciTech Connect

    Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; Hong, Kunlun; Bonnesen, Peter V.; Sumpter, Bobby G.; Smith, Gregory Scott; Ivanov, Ilia N.; Do, Changwoo

    2015-07-17

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.

  3. Direct x-ray detection with conjugated polymer devices

    NASA Astrophysics Data System (ADS)

    Boroumand, F. A.; Zhu, M.; Dalton, A. B.; Keddie, J. L.; Sellin, P. J.; Gutierrez, J. J.

    2007-07-01

    The authors report the first direct detection of x-ray induced photocurrents in thick films (up to 20μm) of conjugated polymers. Schottky-based "sandwich" structures were fabricated from layers of either poly[1-methoxy-4-(2-ethylhexyloxy)-phenylenevinylene] (MEH-PPV) or poly(9,9-dioctylfluorene) (PFO) on indium tin oxide substrates using a top contact of aluminum. Good rectification was achieved from the Al-polymer contact, with a reverse bias leakage current density as low as 4nA/cm2 at an electric field strength of 25kV/cm. Irradiation with x-rays from a 50kV x-ray tube produced a linear increase in photocurrent over a dose rate range from 4to18mGy/s. The observed x-ray sensitivities of 240nC/mGy/cm3 for MEH-PPV and 480nC/mGy/cm3 for PFO structures are comparable to that reported for Si devices. A response time of <150ms to pulsed x-ray irradiation was measured with no evidence of long-lived current transients. Conjugated polymers offer the advantage of easy coatability over large areas and on curved surfaces. Their low average atomic number provides tissue-equivalent dosimetric response, with many potential applications including medical x-ray and synchrotron photon detection.

  4. Releasable Conjugation of Polymers to Proteins.

    PubMed

    Gong, Yuhui; Leroux, Jean-Christophe; Gauthier, Marc A

    2015-07-15

    Many synthetic strategies are available for preparing well-defined conjugates of peptides/proteins and polymers. Most reports on this topic involve coupling methoxy poly(ethylene glycol) to therapeutic proteins, a process referred to as PEGylation, to increase their circulation lifetime and reduce their immunogenicity. Unfortunately, the major dissuading dogma of PEGylation is that, in many cases, polymer modification leads to significant (or total) loss of activity/function. One approach that is gaining momentum to address this challenge is to release the native protein from the polymer with time in the body (releasable PEGylation). This contribution will present the state-of-the-art of this rapidly evolving field, with emphasis on the chemistry behind the release of the peptide/protein and the means for altering the rate of release in biological fluids. Linkers discussed include those based on the following: substituted maleic anhydride and succinates, disulfides, 1,6-benzyl-elimination, host-guest interactions, bicin, β-elimination, biodegradable polymers, E1cb elimination, β-alanine, photoimmolation, coordination chemistry, zymogen activation, proteolysis, and thioesters.

  5. Slow rupture of polymer films

    NASA Astrophysics Data System (ADS)

    Kliakhandler, Igor

    2004-11-01

    Bursting of soap film is a fast and fascinating process. It turns out that certain polymer films rupture in a somewhat similar fashion, but much slower. The slowness of the process allows one to study the rupture of polymer films with details. The rupture process in Hele-Shaw-like fashion shows remarkable properties, and is a very simple system. It turns out that propagation speed of the rupture is a function of the film thickness, and rheologic properties of the polymer. Experimental results will be compared with theory, together with demonstration of the experiment.

  6. Morphology dependent amplified spontaneous emission in π-conjugated polymer

    NASA Astrophysics Data System (ADS)

    Wang, Yuchen; Yang, Xiao; Wang, Ruizhi; Li, Li; Li, Heng

    2015-08-01

    The amplified spontaneous emission (ASE) spectra of a π-conjugated polymer Poly [2-methoxy-5-(2‧-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) are studied in as-cast film, annealed film, 1 mg/ml solution and 2.5 mg/ml solution, respectively, using a 10 ns pulsed laser as an excitation source. We found that for annealed film (420 K), the ASE is hardly achieved compared to the as-cast film, which is consistent with the formation of the aggregation; whereas the film's temperature had much less effect on its ASE threshold. In solution, the ASE spectra show both 0-0 peak and 0-1 peak in 1 mg/ml solution, but only 0-1 peak in 2.5 mg/ml one. When the temperature of solution increases slightly from 300 K to 330 K, the ASE threshold increases dramatically in 1 mg/ml solution but slightly in 2.5 mg/ml one. Our results show the important role the morphology played in the ASE spectra in both film and solution. Therefore, controlling the interchain interaction in PCPs may be the key factor for performance of the organic lasers.

  7. Characterization of pi-Conjugated Polymers for Transistor and Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Paulsen, Bryan D.

    pi-Conjugated polymers represent a unique class of optoelectronic materials. Being polymers, they are solution processable and inherently "soft" materials. This makes them attractive candidates for the production of roll-to-roll printed electronic devices on flexible substrates. The optical and electronic properties of pi-conjugated polymers are synthetically tunable allowing material sets to be tailored to specific applications. Two of the most heavily researched applications are the thin film transistor, the building block of electronic circuits, and the bulk heterojunction solar cell, which holds great potential as a renewable energy source. Key to developing commercially feasible pi-conjugated polymer devices is a thorough understanding of the electronic structure and charge transport behavior of these materials in relationship with polymer structure. Here this structure property relationship has been investigated through electrical and electrochemical means in concert with a variety of other characterization techniques and device test beds. The tunability of polymer optical band gap and frontier molecular orbital energy level was investigated in systems of vinyl incorporating statistical copolymers. Energy levels and band gaps are crucial parameters in developing efficient photovoltaic devices, with control of these parameters being highly desirable. Additionally, charge transport and density of electronic states were investigated in pi-conjugated polymers at extremely high electrochemically induced charge density. Finally, the effects of molecular weight on pi-conjugated polymer optical properties, energy levels, charge transport, morphology, and photovoltaic device performance was examined.

  8. Emerging Synthetic Techniques for Protein-Polymer Conjugations

    PubMed Central

    Broyer, Rebecca M.; Grover, Gregory N.; Maynard, Heather D.

    2011-01-01

    Protein-polymer conjugates are important in diverse fields including drug delivery, biotechnology, and nanotechnology. This feature article highlights recent advances in the synthesis and application of protein-polymer conjugates by controlled radical polymerization techniques. Special emphasis on new applications of the materials, particularly in biomedicine, are highlighted. PMID:21229146

  9. Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

    DOEpatents

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1997-06-17

    A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines. 19 figs.

  10. Enzyme linked immunoassay with stabilized polymer saccharide enzyme conjugates

    DOEpatents

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1997-11-25

    An improvement in enzyme linked immunoassays is disclosed wherein the enzyme is in the form of a water soluble polymer saccharide conjugate which is stable in hostile environments. The conjugate comprises the enzyme which is linked to the polymer at multiple points through saccharide linker groups. 19 figs.

  11. Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

    DOEpatents

    Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

    1997-01-01

    A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines.

  12. Enzyme linked immunoassay with stabilized polymer saccharide enzyme conjugates

    DOEpatents

    Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

    1997-01-01

    An improvement in enzyme linked immunoassays is disclosed wherein the enzyme is in the form of a water soluble polymer saccharide conjugate which is stable in hostile environments. The conjugate comprises the enzyme which is linked to the polymer at multiple points through saccharide linker groups.

  13. Conformational effects on excitation transport along conjugated polymer chains.

    PubMed

    Van Averbeke, Bernard; Beljonne, David

    2009-03-26

    The dynamics of energy transport along rigid rod conjugated polymer--poly(p-phenylenebutadyine)--chains is modeled with a special emphasis on the role of conformational disorder. A simple random growth algorithm based on torsion potentials with increasing stiffness yields polymer chains with increasing degree of conjugation and narrower energetic distributions. Despite the fact that the average hopping rate between two subunits is reduced (because the decrease in electronic coupling overwhelms the increase in spectral overlap), a more efficient excitation motion along chains with longer conjugated segments is predicted, in good agreement with recent experiments. This points to the central role of conformational disorder on intrachain energy diffusion in conjugated polymers.

  14. Singlet fission of hot excitons in π-conjugated polymers.

    PubMed

    Zhai, Yaxin; Sheng, Chuanxiang; Vardeny, Z Valy

    2015-06-28

    We used steady-state photoinduced absorption (PA), excitation dependence (EXPA(ω)) spectrum of the triplet exciton PA band, and its magneto-PA (MPA(B)) response to investigate singlet fission (SF) of hot excitons into two separated triplet excitons, in two luminescent and non-luminescent π-conjugated polymers. From the high energy step in the triplet EXPA(ω) spectrum of the luminescent polymer poly(dioctyloxy)phenylenevinylene (DOO-PPV) films, we identified a hot-exciton SF (HE-SF) process having threshold energy at E≈2E(T) (=2.8 eV, where ET is the energy of the lowest lying triplet exciton), which is about 0.8 eV above the lowest singlet exciton energy. The HE-SF process was confirmed by the triplet MPA(B) response for excitation at E>2E(T), which shows typical SF response. This process is missing in DOO-PPV solution, showing that it is predominantly interchain in nature. By contrast, the triplet EXPA(ω) spectrum in the non-luminescent polymer polydiacetylene (PDA) is flat with an onset at E=E(g) (≈2.25 eV). From this, we infer that intrachain SF that involves a triplet-triplet pair state, also known as the 'dark' 2A(g) exciton, dominates the triplet photogeneration in PDA polymer as E(g)>2E(T). The intrachain SF process was also identified from the MPA(B) response of the triplet PA band in PDA. Our work shows that the SF process in π-conjugated polymers is a much more general process than thought previously.

  15. Synthesis and Characterization of Bioactive Tamoxifen-conjugated Polymers

    PubMed Central

    Rickert, Emily L.; Trebley, Joseph P.; Peterson, Anton C.; Morrell, Melinda M.; Weatherman, Ross V.

    2008-01-01

    Macromolecular conjugates of tamoxifen could perhaps be used to circumvent some of the limitations of the extensively used breast cancer drug. To test the feasibility of these conjugates, a 4-hydroxytamoxifen analog was conjugated to a diaminoalkyl linker and then conjugated to activated esters of a poly(methacrylic acid) polymer synthesized by atom transfer radical polymerization. A polymer conjugated to the 4-hydroxytamoxifen analog with a six carbon linker showed high affinity for both estrogen receptor alpha and estrogen receptor beta and potent antagonism of the estrogen receptor in cell-based transcriptional reporter assays. These results suggest that the conjugation of 4-hydroxytamoxifen to a polymer results in a macromolecular conjugate that can display ligand in a manner that can be recognized by estrogen receptor and still act as a potent antiestrogen in cells. PMID:17929966

  16. Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect

    SciTech Connect

    Li, Xin; Sanchez-Diaz, Luis E.; Smith, Gregory Scott; Chen, Wei-Ren

    2015-01-13

    This work presents scattering functions of conjugates consisting of a colloid particle and a self-avoiding polymer chain as a model for protein-polymer conjugates and nanoparticle-polymer conjugates in solution. The model is directly derived from the two-point correlation function with the inclusion of excluded volume effects. The dependence of the calculated scattering function on the geometric shape of the colloid and polymer stiffness is investigated. The model is able to describe the experimental scattering signature of the solutions of suspending hard particle-polymer conjugates and provide additional conformational information. This model explicitly elucidates the link between the global conformation of a conjugate and the microstructure of its constituent components.

  17. Changes in the Solution Behavior of Conjugated Polymers with Light Absorption

    NASA Astrophysics Data System (ADS)

    Dadmun, Mark; Morgan, Brian

    2015-03-01

    Conjugated polymers are well established as functional materials in a broad range of applications including organic photovoltaics, chemical sensors, and organic light emitting diodes. This functionality is mainly derived from their ability to create electron-hole pair excitons through photoexcitation. The presence of these entities on the polymer chains may alter the chain conformation, solution behavior, and ultimately macroscopic morphology, of the conjugated polymer. Previous studies have shown significant changes in properties such as viscosity and photoluminescence upon exposure of select conjugated polymer films to white light. In order to expand upon these preliminary findings, we have performed small angle neutron scattering experiments on solutions of several semiconducting, conjugated polymers in both the presence and absence of incident light. Substantial differences are observed between the light vs dark samples, the magnitude of which are dependent on polymer dispersion, solvent choice, and solution concentration. Analysis of the neutron curves shows real difference in Kuhn lengths and radius of gyration of the polymer, suggesting possible rearrangement of polymer chain conformation or alteration of polymer chain-solvent interactions.

  18. Thin film-coated polymer webs

    DOEpatents

    Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

    1992-02-04

    The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

  19. Soft molding lithography of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Pisignano, Dario; Persano, Luana; Cingolani, Roberto; Gigli, Giuseppe; Babudri, Francesco; Farinola, Gianluca M.; Naso, Francesco

    2004-02-01

    We report on the nanopatterning of conjugated polymers by soft molding, and exploit the glass transition of the organic compound in conformal contact with an elastomeric element. We succeeded in printing different compounds with resolution down to 300 nm at temperatures up to 300 °C in vacuum. No significant variation of the photoluminescence (PL) spectra nor heavy degradation of the PL quantum yield was observed after the lithography process. Based on the high resolution achieved and on the well-retained luminescence properties of the patterned compounds, we conclude that high-temperature soft lithography is a valid, flexible and straightforward technique for one-step realization of organic-based devices.

  20. Interfacial Widths of Conjugated Polymer Bilayers

    SciTech Connect

    NCSU; UC Berkeley; UCSB; Advanced Light Source; Garcia, Andres; Yan, Hongping; Sohn, Karen E.; Hexemer, Alexander; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Kramer, Edward J.; Ade, Harald

    2009-08-13

    The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.

  1. Charge Injection and Transport in Conjugated Polymers.

    NASA Astrophysics Data System (ADS)

    Malliaras, George

    2007-03-01

    We will overview the state-of-the-art in our understanding of charge injection and transport in conjugated polymers. We start by discussing the identifying characteristics of this class of materials, especially in relation with their structure and morphology. We follow by reviewing the advantages and limitations of experimental techniques that are used to probe charge transport. We then embark on a discussion of the fundamentals of charge transport in organics. We follow a didactic approach, where we start from transport in crystalline semiconductors and gradually introduce corrections for space charge effects, for the influence of disorder on mobility, for high charge densities, and for electric field-dependent charge densities. We compare with experimental data from polyfluorenes. We then shift our attention to charge injection. We review some of the recent theories and compared their predictions to experimental data, again from polyfluorenes. We close by proposing directions for future work.

  2. Polymer decorated gold nanoparticles in nanomedicine conjugates.

    PubMed

    Capek, Ignác

    2017-02-15

    Noble metal, especially gold nanoparticles and their conjugates with biopolymers have immense potential for disease diagnosis and therapy on account of their surface plasmon resonance (SPR) enhanced light scattering and absorption. Conjugation of noble metal nanoparticles to ligands specifically targeted to biomarkers on diseased cells allows molecular-specific imaging and detection of disease. The development of smart gold nanoparticles (AuNPs) that can deliver therapeutics at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating cancer tumors. We highlight some of the promising classes of targeting systems that are under development for the delivery of gold nanoparticles. Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups to conjugate targeting ligands, cell receptors or drugs. Using targeted nanoparticles to deliver chemotherapeutic agents in cancer therapy offers many advantages to improve drug/gene delivery and to overcome many problems associated with conventional radiotherapy and chemotherapy. The targeted nanoparticles were found to be effective in killing cancer cells which were studied using various anticancer assays. Cell morphological analysis shows the changes occurred in cancer cells during the treatment with AuNPs. The results determine the influence of particle size and concentration of AuNPs on their absorption, accumulation, and cytotoxicity in model normal and cancer cells. As the mean particle diameter of the AuNPs decreased, their rate of absorption by the intestinal epithelium cells increased. These results provide important insights into the relationship between the dimensions of AuNPs and their gastrointestinal uptake and potential cytotoxicity. Furthermore gold nanoparticles efficiently convert the absorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. We also review

  3. Polymer-Drug Conjugates: Recent Development in Clinical Oncology

    PubMed Central

    Li, Chun; Wallace, Sidney

    2008-01-01

    Targeted drug delivery aims to increase the therapeutic index by making more drug molecules available at the diseased sites while reducing systemic drug exposure. In this update, we provide an overview of polymer-drug conjugates that have advanced into the clinical trials. These systems use synthetic water-soluble polymers as the drug carriers. The preclinical pharmacology and recent data in clinical trials with poly(L-glutamic acid)-paclitaxel (PG-TXL) are discussed first. This is followed by a summary of conjugates of a variety of polymeric conjugates with chemotherapeutic agents. Results from early clinical trials of these polymer-drug conjugates have demonstrated several advantages over the corresponding parent drugs, including fewer side effects, enhanced therapeutic efficacy, ease of drug administration, and improved patient compliance. Collectively, these data warrant further clinical development of polymer-drug conjugates as a new class of anticancer agents. PMID:18374448

  4. Design of Self-Assembling Protein-Polymer Conjugates.

    PubMed

    Carter, Nathan A; Geng, Xi; Grove, Tijana Z

    Protein-polymer conjugates are of particular interest for nanobiotechnology applications because of the various and complementary roles that each component may play in composite hybrid-materials. This chapter focuses on the design principles and applications of self-assembling protein-polymer conjugate materials. We address the general design methodology, from both synthetic and genetic perspective, conjugation strategies, protein vs. polymer driven self-assembly and finally, emerging applications for conjugate materials. By marrying proteins and polymers into conjugated bio-hybrid materials, materials scientists, chemists, and biologists alike, have at their fingertips a vast toolkit for material design. These inherently hierarchical structures give rise to useful patterning, mechanical and transport properties that may help realize new, more efficient materials for energy generation, catalysis, nanorobots, etc.

  5. Statistical conjugated polymers comprising optoelectronically distinct units.

    PubMed

    Hollinger, Jon; Sun, Jing; Gao, Dong; Karl, Dominik; Seferos, Dwight S

    2013-03-12

    Poly(3-heptylselenophene)-stat-poly(3-hexylthiophene) is synthesized and characterized in terms of its crystallinity and performance in an organic photovoltaic (OPV) cell. Despite the random distribution of units along the polymer main chain, the material is semi-crystalline, as demonstrated by differential scanning calorimetry and wide-angle X-ray diffraction. Thin-film absorption suggests an increased compatibility than seen with 3-hexylselenophene monomer. Optoelectronic properties are an average of the two homopolymers, and OPV performance is enhanced by a broadened absorption profile and a favorable morphology.

  6. Advances in Polymer and Polymeric Nanostructures for Protein Conjugation

    PubMed Central

    González-Toro, Daniella C.; Thayumanavan, S.

    2013-01-01

    Linear polymers have been considered the best molecular structures for the formation of efficient protein conjugates due to their biological advantages, synthetic convenience and ease of functionalization. In recent years, much attention has been dedicated to develop synthetic strategies that produce the most control over protein conjugation utilizing linear polymers as scaffolds. As a result, different conjugate models, such as semitelechelic, homotelechelic, heterotelechelic and branched or star polymer conjugates, have been obtained that take advantage of these well-controlled synthetic strategies. Development of protein conjugates using nanostructures and the formation of said nanostructures from protein-polymer bioconjugates are other areas in the protein bioconjugation field. Although several polymer-protein technologies have been developed from these discoveries, few review articles have focused on the design and function of these polymers and nanostructures. This review will highlight some recent advances in protein-linear polymer technologies that employ protein covalent conjugation and successful protein-nanostructure bioconjugates (covalent conjugation as well) that have shown great potential for biological applications. PMID:24058205

  7. Helically assembled π-conjugated polymers with circularly polarized luminescence

    PubMed Central

    Watanabe, Kazuyoshi; Akagi, Kazuo

    2014-01-01

    We review the recent progress in the field of helically assembled π-conjugated polymers, focusing on aromatic conjugated polymers with interchain helical π-stacking that exhibit circularly polarized luminescence (CPL). In Part 1, we discuss optically active polymers with white-colored CPL and the amplification of the circular polarization through liquid crystallinity. In Part 2, we focus on the stimuli-responsive CPL that results from changes in the conformation and aggregation state of π-conjugated molecules and polymers. In Part 3, we discuss the self-assembly of achiral cationic π-conjugated polymers into circularly polarized luminescent supramolecular nanostructures with the aid of other chiral molecules. PMID:27877698

  8. Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect

    DOE PAGES

    Li, Xin; Sanchez-Diaz, Luis E.; Smith, Gregory Scott; ...

    2015-01-13

    This work presents scattering functions of conjugates consisting of a colloid particle and a self-avoiding polymer chain as a model for protein-polymer conjugates and nanoparticle-polymer conjugates in solution. The model is directly derived from the two-point correlation function with the inclusion of excluded volume effects. The dependence of the calculated scattering function on the geometric shape of the colloid and polymer stiffness is investigated. The model is able to describe the experimental scattering signature of the solutions of suspending hard particle-polymer conjugates and provide additional conformational information. This model explicitly elucidates the link between the global conformation of a conjugatemore » and the microstructure of its constituent components.« less

  9. Effects of a heavy atom on molecular order and morphology in conjugated polymer:fullerene photovoltaic blend thin films and devices.

    PubMed

    Tsoi, Wing C; James, David T; Domingo, Ester Buchaca; Kim, Jong Soo; Al-Hashimi, Mohammed; Murphy, Craig E; Stingelin, Natalie; Heeney, Martin; Kim, Ji-Seon

    2012-11-27

    We study the molecular order and morphology in poly(3-hexylthiophene) (P3HT) and poly(3-hexylselenophene) (P3HS) thin films and their blends with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). We find that substitution of the sulfur atoms in the thiophene rings of P3HT by heavy selenium atoms increases the tendency of the molecules to form better ordered phase; interestingly, their overall fraction of ordered phase is much lower than that of P3HT-based films. The higher tendency of P3HS molecules to order (aggregate) is consistent with more planar chain conformation simulated. The lower fraction of ordered phase (or the higher fraction of disordered phase) in P3HS-based films is clearly identified by in-plane skeleton Raman modes under resonant excitation conditions, such as a smaller ratio of the C═C modes associated with the ordered (∼1422 cm(-1)) and disordered (∼1446 cm(-1)) phases (I(1422 cm(-1))/I(1446 cm(-1)) = 1.4 for P3HS and 0.6 for P3HS:PCBM), compared with P3HT-based films (I(1449 cm(-1))/I(1470 cm(-1)) = 2.5 for P3HT and 1.0 for P3HT:PCBM) and a larger Raman dispersion of the C═C mode: P3HS (17 cm(-1)) versus P3HT (6 cm(-1)) and P3HS:PCBM (36 cm(-1)) versus P3HT:PCBM films (23 cm(-1)). The higher fraction of disordered phase in P3HS prevents the formation of micrometer-sized PCBM aggregates in blend films during thermal annealing. Importantly, this lower fraction but better quality of ordered phase in P3HS molecules strongly influences P3HS:PCBM photovoltaic performance, producing smaller short-circuit current (J(sc)) in pristine devices, but significantly larger increase in J(sc) after annealing compared to P3HT:PCBM devices. Our results clarify the effects of heavy atom substitution in low band gap polymers and their impact on blend morphology and device performance. Furthermore, our study clearly demonstrates resonant Raman spectroscopy as a simple, but powerful, structural probe which provides important information about "fraction

  10. Self-assembly of conjugated oligomers and polymers at the interface: structure and properties.

    PubMed

    Xu, Lirong; Yang, Liu; Lei, Shengbin

    2012-08-07

    conjugated oligomers and polymers. The information obtained could benefit the understanding of the elements affecting the film morphology and helps the optimization of device performance.

  11. Anomalous Charge Transport in Conjugated Polymers Reveals Underlying Mechanisms of Trapping and Percolation

    PubMed Central

    2016-01-01

    While transport in conjugated polymers has many similarities to that in crystalline inorganic materials, several key differences reveal the unique relationship between the morphology of polymer films and the charge mobility. We develop a model that directly incorporates the molecular properties of the polymer film and correctly predicts these unique transport features. At low degree of polymerization, the increase of the mobility with the polymer chain length reveals trapping at chain ends, and saturation of the mobility at high degree of polymerization results from conformational traps within the chains. Similarly, the inverse field dependence of the mobility reveals that transport on single polymer chains is characterized by the ability of the charge to navigate around kinks and loops in the chain. These insights emphasize the connection between the polymer conformations and the transport and thereby offer a route to designing improved device morphologies through molecular design and materials processing. PMID:28058280

  12. Anomalous charge transport in conjugated polymers reveals underlying mechanisms of trapping and percolation

    DOE PAGES

    Mollinger, Sonya A.; Salleo, Alberto; Spakowitz, Andrew J.

    2016-11-10

    While transport in conjugated polymers has many similarities to that in crystalline inorganic materials, several key differences reveal the unique relationship between the morphology of polymer films and the charge mobility. We develop a model that directly incorporates the molecular properties of the polymer film and correctly predicts these unique transport features. At low degree of polymerization, the increase of the mobility with the polymer chain length reveals trapping at chain ends, and saturation of the mobility at high degree of polymerization results from conformational traps within the chains. Similarly, the inverse field dependence of the mobility reveals that transportmore » on single polymer chains is characterized by the ability of the charge to navigate around kinks and loops in the chain. Lastly, these insights emphasize the connection between the polymer conformations and the transport and thereby offer a route to designing improved device morphologies through molecular design and materials processing.« less

  13. Terahertz emission from biased conjugated polymers excited by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Unuma, Takeya; Yamada, Naruki; Kishida, Hideo

    2016-12-01

    We perform terahertz emission spectroscopy to investigate the ultrafast motion of electrons and holes in conjugated polymer films excited by femtosecond laser pulses under in-plane bias electric field. The terahertz waveforms are found to exhibit not the features of free carrier acceleration along bias electric field but a characteristic shape reproduced well by the second time derivative of a delta-function-like polarization. Linear-to-quadratic relations between the terahertz emission amplitude and the excitation intensity are observed for three different conjugated polymers, indicating that the polarization is created by either exciton formation or optical rectification involving two-step excitation via localized states.

  14. Intermolecular Interaction Effects on the Ultrafast Depolarization of the Optical Emission from Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Chang, M. H.; Frampton, M. J.; Anderson, H. L.; Herz, L. M.

    2007-01-01

    We have investigated the effect of interchain interactions on the ultrafast depolarization of the photoluminescence from solid films of a conjugated polymer. Accurate control was exercised over the interchain separation by threading of the conjugated chains with insulating macrocycles or complexation with an inert host polymer. Our measurements indicate that excitation into the higher electronic states of a chain aggregate is followed by a fast (<100fs) relaxation into lower excited states with an associated rotation of the transition dipole moment. These findings emphasize the need for consideration of initial excitonic delocalization across more than one polymeric chain.

  15. Polymer-cysteamine conjugates: new mucoadhesive excipients for drug delivery?

    PubMed

    Kast, Constantia E; Bernkop-Schnürch, Andreas

    2002-03-02

    In the present study, the features of two new thiolated polymers--the so-called thiomers--were investigated. Mediated by a carbodiimide cysteamine was covalently attached to sodium carboxymethylcellulose (Na-CMC) and neutralised polycarbophil (Na-PCP). Depending on the weight-ratio polymer to cysteamine during the coupling reaction, the resulting CMC-cysteamine conjugate and PCP-cysteamine conjugate showed in maximum 43 +/- 15 and 138 +/- 22 micromole thiol groups per g polymer (mean +/- S.D.; n=3), respectively, which were used for further characterisation. Tensile studies carried out with the CMC-cysteamine conjugate on freshly excised porcine intestinal mucosa displayed no significantly (P<0.01) improved mucoadhesion, whereas, the mucoadhesive properties of the PCP-cysteamine conjugate were increased 2.5-fold compared with the unmodified polymer. The swelling behaviour of the CMC-cysteamine conjugate was uninfluenced by the covalent attachment of the sulfhydryl compound. In contrast the swelling behaviour of the PCP-cysteamine conjugate was improved significantly (P<0.01) versus unmodified PCP. Furthermore, in aqueous solutions the disintegration time of tablets based on the CMC- and PCP-cysteamine conjugates was prolonged 1.5 and 3.2-fold, respectively, in comparison to tablets containing the corresponding unmodified polymers. According to these results, especially the PCP-cysteamine conjugate represents a promising new pharmaceutical excipient for various drug delivery systems.

  16. Recent Advances in Conjugated Polymers for Light Emitting Devices

    PubMed Central

    AlSalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

    2011-01-01

    A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

  17. Recent advances in conjugated polymers for light emitting devices.

    PubMed

    Alsalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

    2011-01-01

    A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review.

  18. Highly emissive 'frozen-in' conjugated polymer nanofibers.

    PubMed

    Jin, Young-Jae; Lee, Wang-Eun; Lee, Chang-Lyoul; Kwak, Giseop

    2016-05-11

    Conjugated-polymer nanofibers with a thermodynamically stable, coarsened, disordered structure in an amorphous glassy state were fabricated via a freeze-drying method using a poly(diphenylacetylene) derivative. The nanofibers were extremely emissive, with a fluorescence (FL) quantum yield of approximately 0.34, which was much higher than that of both the cast film (0.02) and the solution (0.21). Similarly, the amplitude-weighted average FL lifetime of the nanofibers was 0.74 ns, which was much longer than that of the film (0.29 ns) and the solution (0.57 ns). This unusual and enhanced FL-emission behavior was attributed to the abruptly quenched chain structure that was created by the freeze-drying process. The polymer chains in the nanofibers remained frozen-in and the side phenyl rings were retained in a relaxed state. The metastable chains did not undergo vibrational relaxation and collisional quenching to generate the radiative emission decay effectively.

  19. Nanostructured conjugated polymers in chemical sensors: synthesis, properties and applications.

    PubMed

    Correa, D S; Medeiros, E S; Oliveira, J E; Paterno, L G; Mattoso, Luiz C

    2014-09-01

    Conjugated polymers are organic materials endowed with a π-electron conjugation along the polymer backbone that present appealing electrical and optical properties for technological applications. By using conjugated polymeric materials in the nanoscale, such properties can be further enhanced. In addition, the use of nanostructured materials makes possible miniaturize devices at the micro/nano scale. The applications of conjugated nanostructured polymers include sensors, actuators, flexible displays, discrete electronic devices, and smart fabric, to name a few. In particular, the use of conjugated polymers in chemical and biological sensors is made feasible owning to their sensitivity to the physicochemical conditions of its surrounding environment, such as chemical composition, pH, dielectric constant, humidity or even temperature. Subtle changes in these conditions bring about variations on the electrical (resistivity and capacitance), optical (absorptivity, luminescence, etc.), and mechanical properties of the conjugated polymer, which can be precisely measured by different experimental methods and ultimately associated with a specific analyte and its concentration. The present review article highlights the main features of conjugated polymers that make them suitable for chemical sensors. An especial emphasis is given to nanostructured sensors systems, which present high sensitivity and selectivity, and find application in beverage and food quality control, pharmaceutical industries, medical diagnosis, environmental monitoring, and homeland security, and other applications as discussed throughout this review.

  20. Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV conjugated polymer to develop nanocomposite films for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Mighri, F.; Duong, Vu Thi Thuy; On, Do Trong; Ajji, A.

    2014-05-01

    This study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different shapes (nanospheres, nanorods and nanorhombics) using oleic acid (OA) and oleyl amine (OM) as capping agents. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. It was found that the shape of NPs and the amount of OA and OM surfactants capped on their surface have an effect on their energy bandgap and also on the dispersion quality of MEH-PPV/TiO2 nanocomposites. Even though there was no evidence of chemical bonding between MEH-PPV matrix and TiO2 dispersed NPs, MEH-PPV/TiO2 nanocomposites showed very promising results for light absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs, which are two main characteristics for photovoltaic materials.

  1. Synthesis of capped TiO{sub 2} nanocrystals of controlled shape and their use with MEH-PPV conjugated polymer to develop nanocomposite films for photovoltaic applications

    SciTech Connect

    Mighri, F. E-mail: Thi-Thuy-Duong.vu.1@ulaval.ca; Duong, Vu Thi Thuy E-mail: Thi-Thuy-Duong.vu.1@ulaval.ca; On, Do Trong; Ajji, A.

    2014-05-15

    This study presents the synthesis details of titanium dioxide (TiO{sub 2}) nanoparticles (NPs) of different shapes (nanospheres, nanorods and nanorhombics) using oleic acid (OA) and oleyl amine (OM) as capping agents. In order to develop nanocomposite thin films for photovoltaic cells, these TiO{sub 2} NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO{sub 2} NPs and MEH-PPV/TiO{sub 2} nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. It was found that the shape of NPs and the amount of OA and OM surfactants capped on their surface have an effect on their energy bandgap and also on the dispersion quality of MEH-PPV/TiO{sub 2} nanocomposites. Even though there was no evidence of chemical bonding between MEH-PPV matrix and TiO2 dispersed NPs, MEH-PPV/TiO{sub 2} nanocomposites showed very promising results for light absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO{sub 2} dispersed NPs, which are two main characteristics for photovoltaic materials.

  2. A photo-oxidation mechanism for patterning and hologram formation in conjugated polymer/glass composites

    NASA Astrophysics Data System (ADS)

    Levi, Ofer; Perepelitsa, Galina; Davidov, Dan; Shalom, Shoshy; Benjamin, Iris; Neumann, Ronny; Agranat, Aharon J.; Avny, Yair

    2000-08-01

    Improved diffraction efficiency was observed in holograms stored in disordered conjugated polymer/glass composites. The conjugated polymers used were alkoxy substituted poly(phenylenevinylne) analogs and the glass matrices were zirconia-organosilica xerogels. Investigation of the mechanism of hologram formation revealed evidence of a photochromic process consisting of light induced photo-oxidation (bleaching) of the embedded conjugated polymer resulting in the formation of an absorption grating and a phase grating. Investigation of the hologram formation revealed that the process was oxygen dependent. Oxygen removal increases hologram formation time by more than an order of magnitude and halves the total hologram efficiency. The oxygen dependence was also highly correlated with photobleaching of the samples and beam interaction of the writing beams. The chemical transformations upon photobleaching were shown by infrared and Raman spectroscopy to involve chain scission and oxidation of the polymer at the vinylic position of the conjugated polymer. Film preparation of the composites was optimized showing a tenfold improvement in the holographic properties compared to our previous results. The optimized treatment method allows for a high, >20%, diffraction efficiency, η, to be obtained for the 2.5-μm-thick polymer/glass films. Light sensitivity was compared for several polymer/glass composites and was correlated to the absorption curves and holographic diffraction efficiency showing that the new composites and film preparation techniques are promising for holographic materials sensitive in the blue and ultraviolet spectral regions. A method of information fixing by preventing oxygen entry to the composite film resulted in a fourfold increase of the erasure time. These findings suggest that holograms can be fixed for a long term by nonoxygen permeable coating, applied after hologram formation.

  3. Band-structure engineering in conjugated 2D polymers.

    PubMed

    Gutzler, Rico

    2016-10-26

    Conjugated polymers find widespread application in (opto)electronic devices, sensing, and as catalysts. Their common one-dimensional structure can be extended into the second dimension to create conjugated planar sheets of covalently linked molecules. Extending π-conjugation into the second dimension unlocks a new class of semiconductive polymers which as a consequence of their unique electronic properties can find usability in numerous applications. In this article the theoretical band structures of a set of conjugated 2D polymers are compared and information on the important characteristics band gap and valence/conduction band dispersion is extracted. The great variance in these characteristics within the investigated set suggests 2D polymers as exciting materials in which band-structure engineering can be used to tailor sheet-like organic materials with desired electronic properties.

  4. Toward High Performance Photovoltaic Cells based on Conjugated Polymers

    DTIC Science & Technology

    2016-12-26

    AFRL-AFOSR-JP-TR-2016-0103 Toward High Performance Photovoltaic Cells based on Conjugated Polymers Kung-Hwa Wei National Chiao Tung University Final...REPORT TYPE Final 3. DATES COVERED (From - To) 16 Sep 2015 to 15 Sep 2016 4. TITLE AND SUBTITLE Toward High Performance Photovoltaic Cells based on...Grant 15IOA0113 “Toward High Performance Photovoltaic Cells Based on Conjugated Polymers (Taiwan side)” Dec. 16, 2016 PI information: Kung-Hwa Wei

  5. Electronic and Morphological Studies of Conjugated Polymers Incorporating a Disk-Shaped Polycyclic Aromatic Hydrocarbon Unit.

    PubMed

    He, Bo; Zhang, Benjamin A; Liu, Feng; Navarro, Amparo; Fernández-Liencres, M Paz; Lu, Ryan; Lo, Kelvin; Chen, Teresa L; Russell, Thomas P; Liu, Yi

    2015-09-16

    As more research findings have shown the correlation between ordering in organic semiconductor thin films and device performance, it is becoming more essential to exercise control of the ordering through structural tuning. Many recent studies have focused on the influence of side chain engineering on polymer packing orientation in thin films. However, the impact of the size and conformation of aromatic surfaces on thin film ordering has not been investigated in great detail. Here we introduce a disk-shaped polycyclic aromatic hydrocarbon building block with a large π surface, namely, thienoazacoronenes (TACs), as a donor monomer for conjugated polymers. A series of medium bandgap conjugated polymers have been synthesized by copolymerizing TAC with electron donating monomers of varying size. The incorporation of the TAC unit in such semiconducting polymers allows a systematic investigation, both experimentally and theoretically, of the relationships between polymer conformation, electronic structure, thin film morphology, and charge transport properties. Field effect transistors based on these polymers have shown good hole mobilities and photoresponses, proving that TAC is a promising building block for high performance optoelectronic materials.

  6. Electronic structure of disordered conjugated polymers: Polythiophenes

    SciTech Connect

    Vukmirovic, Nenad; Wang, Lin-Wang

    2008-11-26

    Electronic structure of disordered semiconducting conjugated polymers was studied. Atomic structure was found from a classical molecular dynamics simulation and the charge patching method was used to calculate the electronic structure with the accuracy similar to the one of density functional theory in local density approximation. The total density of states, the local density of states at different points in the system and the wavefunctions of several states around the gap were calculated in the case of poly(3-hexylthiophene) (P3HT) and polythiophene (PT) systems to gain insight into the origin of disorder in the system, the degree of carrier localization and the role of chain interactions. The results indicated that disorder in the electronic structure of alkyl substituted polythiophenes comes from disorder in the conformation of individualchains, while in the case of polythiophene there is an additional contribution due to disorder in the electronic coupling between the chains. Each of the first several wavefunctions in the conduction and valence band of P3HT is localized over several rings of a single chain. It was shown that the localization can be caused in principle both by ring torsions and chain bending, however the effect of ring torsions is much stronger. PT wavefunctions are more complicated due to larger interchain electronic coupling and are not necessarily localized on a single chain.

  7. Lipid-peptide-polymer conjugates and nanoparticles thereof

    DOEpatents

    Xu, Ting; Dong, He; Shu, Jessica

    2015-06-02

    The present invention provides a conjugate having a peptide with from about 10 to about 100 amino acids, wherein the peptide adopts a helical structure. The conjugate also includes a first polymer covalently linked to the peptide, and a hydrophobic moiety covalently linked to the N-terminus of the peptide, wherein the hydrophobic moiety comprises a second polymer or a lipid moiety. The present invention also provides helix bundles form by self-assembling the conjugates, and particles formed by self-assembling the helix bundles. Methods of preparing the helix bundles and particles are also provided.

  8. A general relationship between disorder, aggregation and charge transport in conjugated polymers.

    PubMed

    Noriega, Rodrigo; Rivnay, Jonathan; Vandewal, Koen; Koch, Felix P V; Stingelin, Natalie; Smith, Paul; Toney, Michael F; Salleo, Alberto

    2013-11-01

    Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials.

  9. Light emitting conjugated polymers for use in biological detection platforms

    NASA Astrophysics Data System (ADS)

    Gaylord, Brent S.

    Recent interest in conjugated polymers has grown from their demonstrated utility in various "plastic" and/or "molecular" electronic applications to include organic light emitting diodes (OLED's), thin film transistors and photovoltaics. Due to their intrinsically delocalized electronic structure, these same materials show enormous potential as highly responsive optical reporters for chemical and biological interactions. Inter- and intra-chain energy migration, coupled with the formation of strong electrostatic complexes between opposite charged acceptors, allows for extraordinary modulation of their fluorescent response. When these properties are correlated with a specific biological recognition event, the result is a biosensor with optically enhanced or amplified performance. Such features are highly desirable in detection schemes where the target analyte is in limited supply, as is most often the case. Within these studies we demonstrate how variations in test media composition (i.e. surfactant, buffers, proteins, DNA, etc.) and molecular structure influence those photophysical properties of conjugated polymers related to biosensor design. To this end, both anionic polyphenylenevinylene (PPV) and cationic polyfluorene-cophenylene structures were examined. Model oligomer structures were employed throughout the study for delineating structure-property relationships, as such detailed correlation is inherently more difficult for the less defined polymeric structures (i.e. polydispersity, batch-to-batch variation, purity, etc.). Studies using light scattering and optical spectroscopy highlight the extensive aggregation of these fluorescent, amphiphilic polyelectrolytes in aqueous solution. Variations in chromophore size, charge and concentration provide interesting comparisons in quenching and/or energy transfer processes, as well as, in their interactions with biological molecules. Ultimately, this information was utilized to develop a novel platform for highly

  10. Molecular structure and exciton dynamics in organic conjugated polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Alan K.

    Intermolecular electronic interactions, dipole coupling and orbital overlap, caused by pi-pi stacking in organic conjugated polymers lead to unique structures and properties that can be harnessed for optoelectronic applications. These interactions define structure-function relationships in amorphous and aggregated forms of polymers in the solid state and determine their efficiencies and functionality in electronic devices, from transistors to solar cells. Organic polymer electronic device performance depends critically upon electronic coupling between monomer units -mediated by conformation and packing characteristics - that dictates electronic properties like conductivity and capacitance as well as electronic processes, such as charge carrier generation and transport. This dissertation demonstrates how electronic processes in conjugated polymers are mediated by subtle inter- and intra-chain electronic interactions imparted by the conformational degrees of freedom within their solid state structure and how this effects device performance. To initiate this investigation into structure-function relationships, an examination of nanoparticles representing two limiting aggregation states of the conjugated polymer poly(3-hexylthiophene) (P3HT) was conducted. These aggregates are defined by their predominate form of electronic coupling, inter- or intrachain, called H- and J-aggregates respectively. H- or J-aggregates of P3HT were embedded in an insulating matrix and time-resolved fluorescence intensity modulation spectroscopy was utilized to uncover the existence of efficient singlet-triplet quenching in J aggregates not present in H-aggregates. These studies were extended by examining P3HT H-and J-aggregates under applied electric fields in capacitor type devices using multiple time-resolved and steady-state spectroscopic techniques. These experiments reveal electronic couplings in J aggregates that shift excited state population towards a majority composed of long lived

  11. Mesoscopic quantum emitters from deterministic aggregates of conjugated polymers

    PubMed Central

    Stangl, Thomas; Wilhelm, Philipp; Remmerssen, Klaas; Höger, Sigurd; Vogelsang, Jan; Lupton, John M.

    2015-01-01

    An appealing definition of the term “molecule” arises from consideration of the nature of fluorescence, with discrete molecular entities emitting a stream of single photons. We address the question of how large a molecular object may become by growing deterministic aggregates from single conjugated polymer chains. Even particles containing dozens of individual chains still behave as single quantum emitters due to efficient excitation energy transfer, whereas the brightness is raised due to the increased absorption cross-section of the suprastructure. Excitation energy can delocalize between individual polymer chromophores in these aggregates by both coherent and incoherent coupling, which are differentiated by their distinct spectroscopic fingerprints. Coherent coupling is identified by a 10-fold increase in excited-state lifetime and a corresponding spectral red shift. Exciton quenching due to incoherent FRET becomes more significant as aggregate size increases, resulting in single-aggregate emission characterized by strong blinking. This mesoscale approach allows us to identify intermolecular interactions which do not exist in isolated chains and are inaccessible in bulk films where they are present but masked by disorder. PMID:26417079

  12. Nanotesla magnetoresistance in π-conjugated polymer devices

    NASA Astrophysics Data System (ADS)

    Klemm, Philippe; Bange, Sebastian; Pöllmann, Agnes; Boehme, Christoph; Lupton, John M.

    2017-06-01

    We demonstrate submicrotesla sensitivity of organic magnetoresistance in thin-film diodes made of the conducting polymer poly(styrene sulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS). The magnetoresistance sensitivity is shown to be better than 20 parts per billion (ppb). As for other conjugated polymers, magnetoresistance can be separated into two regimes of field strength: the nonmonotonic ultrasmall magnetic field effect on magnetic field scales below 2 mT, and the monotonic intermediate magnetic field effect on scales over several tens of mT. The former gives the PEDOT:PSS magnetoresistance curve a characteristic W-shaped functionality, with inverted turning points compared to those found in conventional organic light-emitting diode (OLED) devices. We succeed in resolving the ultrasmall magnetic field effect of the PEDOT:PSS layer incorporated within an OLED structure, which is responsible for an additional magnetoresistive feature on the ppm scale. Such a device shows unprecedented complexity in magnetoresistance with a total of four extrema within a field range of ±1 mT. We propose that these unique characteristics arise from spin-spin interactions in the weakly bound carrier pairs responsible for the spin-dependent recombination probed in magnetoresistance.

  13. Process for crosslinking and extending conjugated diene-containing polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

    1977-01-01

    A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

  14. Controlling Molecular Ordering in Solution-State Conjugated Polymers

    DOE PAGES

    Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; ...

    2015-07-17

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution,more » we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.« less

  15. Monitoring Protein Capsid Assembly with a Conjugated Polymer Strain Sensor.

    PubMed

    Cingil, Hande E; Storm, Ingeborg M; Yorulmaz, Yelda; te Brake, Diane W; de Vries, Renko; Cohen Stuart, Martien A; Sprakel, Joris

    2015-08-12

    Semiconducting polymers owe their optoelectronic properties to the delocalized electronic structure along their conjugated backbone. Their spectral features are therefore uniquely sensitive to the conformation of the polymer, where mechanical stretching of the chain leads to distinct vibronic shifts. Here we demonstrate how the optomechanical response of conjugated polyelectrolytes can be used to detect their encapsulation in a protein capsid. Coating of the sensor polymers by recombinant coat proteins induces their stretching due to steric hindrance between the proteins. The resulting mechanical planarizations lead to pronounced shifts in the vibronic spectra, from which the process of capsid formation can be directly quantified. These results show how the coupling between vibronic states and mechanical stresses inherent to conjugated polymers can be used to noninvasively measure strains at the nanoscale.

  16. Stabilization of Proteins by Polymer Conjugation via ATRP

    DTIC Science & Technology

    2008-08-31

    year basic research effort by ICx-Agentase to study new techniques of modifying native enzymes with polymers via atom transfer radical polymerization ...techniques of modifying native enzymes with polymers via atom transfer radical polymerization to increase their solubility and utility in organic... polymerization of vinyl monomers in aqueous medium to synthesize highly active enzyme- polymer conjugates. In this effort, we proposed to test our

  17. Synthesis and study of conjugated polymers containing Di- or Triphenylamine

    SciTech Connect

    Sukwattanasinitt, M.

    1996-06-21

    This thesis consists of two separate parts. The first part addresses the synthesis and study of conjugated polymers containing di- or triphenylamine. Two types of polymers: linear polymers and dendrimers, were synthesized. The polymers were characterized by NMR, IR, UV, GPC, TGA and DSC. Electronic and optical properties of the polymers were studied through the conductivity measurements and excitation- emission spectra. the second part of this thesis deals with a reaction of electron-rich acetylenes with TCNE. The discovery of the reaction from charge transfer complex studies and the investigation of this reaction on various electron-rich acetylenes are presented.

  18. Photovoltaic cells made from conjugated polymers infiltrated into ordered nanoporous hosts

    NASA Astrophysics Data System (ADS)

    Coakley, Kevin M.

    Semiconducting (conjugated) polymers have several properties which make them ideal candidates for use in low-cost photovoltaic (PV) cells, including their typically high (105 cm-1) optical absorption coefficients, their ability to be cast from solution using a variety of wet-processing techniques, and the ability to tune their band gap. While most approaches for making conjugated polymer-based PV cells involve randomly intermixing the polymers with electron acceptors that act as sites for exciton dissociation, we have sought to obtain a more optimized morphology of the blended materials through a self-assembly technique. In the first half of this dissertation, we describe our preliminary attempts to make PV cells from conjugated polymers infiltrated into a self-assembled mesoporous titanic (TiO 2) electron acceptor that is ordered on the nanometer length scale. We first present a procedure for fabricating films of mesoporous TiO 2 and then show how its pores can be filled with a conjugated polymer, regioregular poly(3-hexylthiophene) (P3HT). In these films we have achieved precise control of the morphology of the two materials that has not yet been achieved elsewhere. However, as discussed subsequently, the photovoltaic performance of these films has not yet reached the level achieved by other types of conjugated polymer-based PV cells, with a maximum achieved power efficiency of approximately 0.45%. In the second half of this dissertation, we embark on a more fundamental study of the materials requirements for efficient polymer photovoltaics, including models that show how the maximum achievable power efficiency is limited by energy loss during forward electron transfer, and how the maximum achievable photocurrent is limited by the limiting carrier mobility and back electron transfer. Our modeling suggests that, for a back recombination time constant of 1 mus, a limiting carrier mobility of 10-3--10 -2 cm2/Vs is required in order to achieve a large photocurrent

  19. Correlating structure with fluorescence emission in phase-separated conjugated-polymer blends.

    PubMed

    Chappell, John; Lidzey, David G; Jukes, Paul C; Higgins, Anthony M; Thompson, Richard L; O'Connor, Stephen; Grizzi, Ilaria; Fletcher, Robert; O'Brien, Jim; Geoghegan, Mark; Jones, Richard A L

    2003-09-01

    Blends of conjugated polymers are frequently used as the active semiconducting layer in light-emitting diodes and photovoltaic devices. Here we report the use of scanning near-field optical microscopy, scanning force microscopy and nuclear-reaction analysis to study the structure of a thin film of a phase-separated blend of two conjugated polymers prepared by spin-casting. We show that in addition to the well-known micrometre-scale phase-separated morphology of the blend, one of the polymers preferentially wets the surface and forms a 10-nm-thick, partially crystallized wetting layer. Using near-field microscopy we identify unexpected changes in the fluorescence emission from the blend that occurs in a 300-nm-wide band located at the interface between the different phase-separated domains. Our measurements provide an insight into the complex structure of phase-separated conjugated-polymer thin films. Characterizing and controlling the properties of the interfaces in such films will be critical in the further development of efficient optoelectronic devices.

  20. Stretchable and Conductive Polymer Films Prepared by Solution Blending.

    PubMed

    Li, Pengcheng; Sun, Kuan; Ouyang, Jianyong

    2015-08-26

    Stretchable and conductive materials can have important application in many areas, such as wearable electronics and healthcare devices. Conducting polymers have very limited elasticity because of their rigid conjugated backbone. In this work, highly stretchable and conductive polymer films are prepared by coating or casting aqueous solution of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate ( PSS) and a soft polymer, including poly(ethylene glycol), poly(ethylene oxide), or poly(vinyl alcohol). The soft polymers can greatly improve the stretchability and the conductivity of PSS. The elongation at break can be increased from 2% up to 55%. The soft polymers can also enhance the conductivity of PSS from 0.2 up to 75 S cm(-1). The conductivity is further enhanced by adding dimethyl sulfoxide (DMSO) or ethylene glycol (EG) into the aqueous solutions of the polymer blends. Polymer blends with an elongation at break of close to 50% and a conductivity of 172 S cm(-1) are attained.

  1. Conjugated polymer-assisted dispersion of single-wall carbon nanotubes: the power of polymer wrapping.

    PubMed

    Samanta, Suman Kalyan; Fritsch, Martin; Scherf, Ullrich; Gomulya, Widianta; Bisri, Satria Zulkarnaen; Loi, Maria Antonietta

    2014-08-19

    coordinates [(n,m) indices]. The polymer wrapping strategy enables the generation of SWNT dispersions containing exclusively semiconducting nanotubes. Toward the applications in electronic devices, until now most applied approach is a direct processing of such SWNT dispersions into the active layer of network-type thin film field effect transistors. However, to achieve promising transistor performance (high mobility and on-off ratio) careful removal of the wrapping polymer chains seems crucial, for example, by washing or ultracentrifugation. More defined positioning of the SWNTs can be accomplished in directed self-assembly procedures. One possible strategy uses diblock copolymers containing a conjugated polymer block as dispersing moiety and a second block for directed self-assembly, for example, a DNA block for specific interaction with complementary DNA strands. Another strategy utilizes reactive side chains for controlled anchoring onto patterned surfaces (e.g., by interaction of thiol-terminated alkyl side chains with gold surfaces). A further promising application of purified SWNT dispersions is the field of organic (all-carbon) or hybrid solar cell devices.

  2. CONJUGATED POLYMERS AND POLYELECTROLYTES IN SOLAR PHOTOCONVERSION, Final Technical Report

    SciTech Connect

    Schanze, Kirk S

    2014-08-05

    This DOE-supported program investigated the fundamental properties of conjugated polyelectrolytes, with emphasis placed on studies of excited state energy transport, self-assembly into conjugated polyelectroyte (CPE) based films and colloids, and exciton transport and charge injection in CPE films constructed atop wide bandgap semiconductors. In the most recent grant period we have also extended efforts to examine the properties of low-bandgap donor-acceptor conjugated polyelectrolytes that feature strong visible light absorption and the ability to adsorb to metal-oxide interfaces.

  3. Ultrathin Polymer Films for Microlithography

    DTIC Science & Technology

    1988-07-13

    exposure the PINAA was developed in a solution made of 3:7 cellosolve : methanol for 13 seconds. Cellosolve was chosen because it is strong enough to...can achieve on thicker resist (> 100 nm) for the same exposure conditions. Recently, we have exposed 14.3 nrm L-B PMMA films on a high resolution...Polymer Films LB PMMA Spin-Cast PNMA Spin-Cast Novolac (10 wafers) (5 wafers) (5 wafers) Film Thickness 14.3 nrm 14 nrm 22 nm Pinhole Density < 10/cm 2

  4. Percolation, tie-molecules, and microstructural origins of charge transport in semicrystalline conjugated polymers (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Mollinger, Sonya A.; Krajina, Brad; Noriega-Manez, Rodrigo J.; Salleo, Alberto; Spakowitz, Andrew J.

    2015-10-01

    Semiconducting polymers play an important role in a wide range of optical and electronic material applications. Polymer thin films that result in the highest performance typically have a complex semicrystalline morphology, indicating that considerable device improvement can be achieved through optimization of microstructural properties. However, the connection between molecular ordering and device performance is difficult to predict due to the current need for a mathematical theory of the physics that dictates charge transport in semiconducting polymers. It is experimentally suggested that efficient transport in such films occurs via connected networks of crystallites. We present an analytical and computational description of semicrystalline conjugated polymer materials that captures the impact of polymer conformation on charge transport in heterogeneous thin films. We first develop an analytical theory for the statistical behavior of a polymer emanating from a crystallite and predict the average distance to the first kink in the chain that traps a charge. We use this analysis to define the conditions for percolation and the consequent efficient transport through a semicrystalline material. We then establish a charge transport model using Monte Carlo simulations that predicts the multi-scale charge transport and crystallite connections. We approximate the thin film as a two-dimensional grid of crystallites embedded in amorphous polymer. The chain conformations in the amorphous region are determined by the wormlike chain model, and the crystallites are assigned fixed mobilities. We use this model to identify limits of charge transport at various time scales for varying fraction of crystallinity.

  5. Conjugated Polymer Design and Engineering for Organic Electronics

    NASA Astrophysics Data System (ADS)

    Woo, Claire Hoi Kar

    The molecular structure of a conjugated polymer critically impacts its physical and optoelectronic properties, thus determining its ultimate performance in organic electronic devices. In this work, new polymers and derivatives are designed, synthesized, characterized, and tested in photovoltaic devices. Through device engineering and nanoscale characterization, general structure-function relationships are established to aid the design of the next-generation of high performance polymer semiconductors for organic electronic applications. Using a prototypical conjugated polymer, the influence of backbone regioregularity is examined and found to highly impact polymer crystallinity, solid state morphology and device stability. The investigation of alternative aromatic units in the backbone also led to new understandings in polymer processability and the development of promising materials for organic photovoltaics. Besides the backbone structure, the side chain choice of the polymer can significantly affect material properties and device performance as well. In fact, the side chain substitution can influence both the optoelectronic properties and the physical properties of the polymer. A sterically bulky side chain can be used to tune the donor/acceptor separation distance, which in turn determines the charge separation efficiency. The addition of a polar side group increases the dielectric constant of a polymer and improves overall charge separation. Choosing the appropriate solubilizing group can also induce solid state packing of the polymer and considerably enhance device efficiency. Finally, the influence of post-fabrication processing techniques on the crystallinity and charge transport properties of a polymer is highlighted.

  6. Novel non-conjugated main-chain hole-transporting polymers for organic electronics application.

    PubMed

    Schelter, Jürgen; Mielke, Georg Felix; Köhnen, Anne; Wies, Jenna; Köber, Sebastian; Nuyken, Oskar; Meerholz, Klaus

    2010-09-01

    A new class of hole-transporting polymers for use in organic electronic devices such as organic light-emitting diodes (OLEDs) or photorefractive holographic storage devices has been synthesized. The polymers contain tetraarylbenzidines or tetraarylphenylenediamines as charge-transporting units in the polymer backbone and are connected by non-conjugating fluorene bridges. For use in OLEDs the novel polymers were functionalized with oxetane groups that can be cross-linked via a cationic ring opening polymerization to yield insoluble networks. Such insoluble films are necessary for the fabrication of multilayer devices by wet deposition techniques. The novel materials feature improved film-formation properties as demonstrated in green-emitting double-layer OLEDs.

  7. Conjugated Polymer Zwitterions: Efficient Interlayer Materials in Organic Electronics.

    PubMed

    Liu, Yao; Duzhko, Volodimyr V; Page, Zachariah A; Emrick, Todd; Russell, Thomas P

    2016-11-15

    Conjugated polymer zwitterions (CPZs) are neutral, hydrophilic, polymer semiconductors. The pendent zwitterions, viewed as side chain dipoles, impart solubility in polar solvents for solution processing, and open opportunities as interfacial components of optoelectronic devices, for example, between metal electrodes and organic semiconductor active layers. Such interlayers are crucial for defining the performance of organic electronic devices, e.g., field-effect transistors (OFETs), light-emitting diodes (OLEDs), and photovoltaics (OPVs), all of which consist of multilayer structures. The interlayers reduce the Schottky barrier height and thus improve charge injection in OFETs and OLEDs. In OPVs, the interlayers serve to increase the built-in electric potential difference (Vbi) across the active layer, ensuring efficient extraction of photogenerated charge carriers. In general, polar and even charged electronically active polymers have gained recognition for their ability to modify metal/semiconductor interfaces to the benefit of organic electronics. While conjugated polyelectrolytes (CPEs) as interlayer materials are well-documented, open questions remain about the role of mobile counterions in CPE-containing devices. CPZs possess the processing advantages of CPEs, but as neutral molecules lack any potential complications associated with counterions. The electronic implications of CPZs on metal electrodes stem from the orientation of the zwitterion dipole moment in close proximity to the metal surface, and the resultant surface-induced polarization. This generates an interfacial dipole (Δ) at the CPZ/metal interface, altering the work function of the electrode, as confirmed by ultraviolet photoelectron spectroscopy (UPS), and improving device performance. An ideal cathode interlayer would reduce electrode work function, have orthogonal processability to the active layer, exhibit good film forming properties (i.e., wettability/uniformity), prevent exciton

  8. Polymer film composite transducer

    DOEpatents

    Owen, Thomas E.

    2005-09-20

    A composite piezoelectric transducer, whose piezoeletric element is a "ribbon wound" film of piezolectric material. As the film is excited, it expands and contracts, which results in expansion and contraction of the diameter of the entire ribbon winding. This is accompanied by expansion and contraction of the thickness of the ribbon winding, such that the sound radiating plate may be placed on the side of the winding.

  9. Naphthobischalcogenadiazole Conjugated Polymers: Emerging Materials for Organic Electronics.

    PubMed

    Osaka, Itaru; Takimiya, Kazuo

    2017-02-27

    π-Conjugated polymers are an important class of materials for organic electronics. In the past decade, numerous polymers with donor-acceptor molecular structures have been developed and used as the active materials for organic devices, such as organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). The choice of the building unit is the primary step for designing the polymers. Benzochalcogenadiazoles (BXzs) are one of the most familiar acceptor building units studied in this area. As their doubly fused system, naphthobischalcogenadiazoles (NXzs), i.e., naphthobisthiadiazole (NTz), naphthobisoxadiazole (NOz), and naphthobisselenadiazole (NSz) are emerging building units that provide interesting electronic properties and highly self-assembling nature for π-conjugated polymers. With these fruitful features, π-conjugated polymers based on these building units demonstrate great performances in OFETs and OPVs. In particular, in OPVs, NTz-based polymers have exhibited more than 10% efficiency, which is among the highest values reported so far. In this Progress Report, the synthesis, properties, and structures of NXzs and their polymers is summarized. The device performance is also highlighted and the structure-property relationships of the polymers are discussed.

  10. Design, synthesis, and structure-property relationships of isoindigo-based conjugated polymers.

    PubMed

    Lei, Ting; Wang, Jie-Yu; Pei, Jian

    2014-04-15

    Conjugated polymers have developed rapidly due to their promising applications in low-cost, lightweight, and flexible electronics. The development of the third-generation donor-acceptor (D-A) polymers greatly improved the device performance in organic solar cells (OSCs) and field-effect transistors (FETs). However, for further improvement of device performance, scientists need to develop new building blocks, in particular electron-deficient aromatics, and gain an in-depth understanding of the structure-property relationships. Recently, isoindigo has been used as a new acceptor of D-A conjugated polymers. An isomer of indigo, isoindigo is a less well-known dye and can be isolated as a by-product from certain biological processes. It has two lactam rings and exhibits strong electron-withdrawing character. This electron deficiency gives isoindigo-based polymers intriguing properties, such as broad absorption and high open circuit voltage in OSCs, as well as high mobility and good ambient stability in FETs. In this Account, we review our recent progress on the design, synthesis, and structure-property relationship study of isoindigo-based polymers for FETs. Starting with some discussion on carrier transport in polymer films, we provide some basic strategies towards high-performance polymer FETs. We discuss the stability issue of devices, the impediment of the alkyl side chains, and the choice of the donor part of conjugated polymers. We demonstrate that introducing the isoindigo core effectively lowers the HOMO levels of polymers and provides FETs with long-time stability. In addition, we have found that when we use inappropriate alkyl side chains or non-centrosymmetric donors, the device performance of isoindigo polymers suffers. To further improve device performance and ambient stability, we propose several design strategies, such as using farther branched alkyl chains, modulating polymer energy levels, and extending π-conjugated backbones. We have found that using

  11. Approaching disorder-free transport in high-mobility conjugated polymers.

    PubMed

    Venkateshvaran, Deepak; Nikolka, Mark; Sadhanala, Aditya; Lemaur, Vincent; Zelazny, Mateusz; Kepa, Michal; Hurhangee, Michael; Kronemeijer, Auke Jisk; Pecunia, Vincenzo; Nasrallah, Iyad; Romanov, Igor; Broch, Katharina; McCulloch, Iain; Emin, David; Olivier, Yoann; Cornil, Jerome; Beljonne, David; Sirringhaus, Henning

    2014-11-20

    Conjugated polymers enable the production of flexible semiconductor devices that can be processed from solution at low temperatures. Over the past 25 years, device performance has improved greatly as a wide variety of molecular structures have been studied. However, one major limitation has not been overcome; transport properties in polymer films are still limited by pervasive conformational and energetic disorder. This not only limits the rational design of materials with higher performance, but also prevents the study of physical phenomena associated with an extended π-electron delocalization along the polymer backbone. Here we report a comparative transport study of several high-mobility conjugated polymers by field-effect-modulated Seebeck, transistor and sub-bandgap optical absorption measurements. We show that in several of these polymers, most notably in a recently reported, indacenodithiophene-based donor-acceptor copolymer with a near-amorphous microstructure, the charge transport properties approach intrinsic disorder-free limits at which all molecular sites are thermally accessible. Molecular dynamics simulations identify the origin of this long sought-after regime as a planar, torsion-free backbone conformation that is surprisingly resilient to side-chain disorder. Our results provide molecular-design guidelines for 'disorder-free' conjugated polymers.

  12. Fluorescent non-conjugated polymer dots for targeted cell imaging

    NASA Astrophysics Data System (ADS)

    Sun, Bin; Zhao, Bin; Wang, Dandan; Wang, Yibo; Tang, Qi; Zhu, Shoujun; Yang, Bai; Sun, Hongchen

    2016-05-01

    Through the chemical crosslinking of the sub-fluorophore, linear non-conjugated polymers can possess strong photoluminescence (PL), which is a very important fluorescence behavior and the non-conjugated polymer dots (PDs) are efficient bio-fluorophores for bio-based applications. Herein, the new type of non-conjugated polyethyleneimine (PEI) PDs was further modified by targeting molecules (folic acid) for a new generation of bio-fluorophores. The free folic acid can quench the PL of PDs by energy transfer, while the conjugated folic acid@PDs (FA@PDs) can still maintain their PL properties to a certain degree. The FA@PDs also possess lower toxicity compared with free PDs, which is possibly due to blocking of the amino groups. Moreover, we investigated the targeted bioimaging applications of the FA@PDs, which gave a very important direction for application of these types of materials.Through the chemical crosslinking of the sub-fluorophore, linear non-conjugated polymers can possess strong photoluminescence (PL), which is a very important fluorescence behavior and the non-conjugated polymer dots (PDs) are efficient bio-fluorophores for bio-based applications. Herein, the new type of non-conjugated polyethyleneimine (PEI) PDs was further modified by targeting molecules (folic acid) for a new generation of bio-fluorophores. The free folic acid can quench the PL of PDs by energy transfer, while the conjugated folic acid@PDs (FA@PDs) can still maintain their PL properties to a certain degree. The FA@PDs also possess lower toxicity compared with free PDs, which is possibly due to blocking of the amino groups. Moreover, we investigated the targeted bioimaging applications of the FA@PDs, which gave a very important direction for application of these types of materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01909a

  13. A Low Reabsorbing Luminescent Solar Concentrator Employing π-Conjugated Polymers.

    PubMed

    Gutierrez, Gregory D; Coropceanu, Igor; Bawendi, Moungi G; Swager, Timothy M

    2016-01-20

    A highly efficient thin-film luminescent solar concentrator (LSC) utilizing two π-conjugated polymers as antennae for small amounts of the valued perylene bisimide Lumogen F Red 305 is presented. The LSC exhibits high photoluminescence quantum yield, low reabsorption, and relatively low refractive indices for waveguide matching. A Monte Carlo simulation predicts the LSC to possess exceptionally high optical efficiencies on large scales. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Effects of thermal annealing on photoluminescence spectra in π-conjugated polymer film: evidence for dual emission by temperature dependent measurements

    NASA Astrophysics Data System (ADS)

    Wang, R. Z.; Yang, X.; Wang, Y. C.; Sheng, C.-X.; Chen, Q.

    2014-09-01

    Various spectroscopy techniques such as absorption, photoluminescence and photoinduced absorption (PIA) spectroscopy, were used to study the photophysics in poly [2-methoxy-5-(20-ethyl-hexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) films, which were dropped cast on glass substrates using its toluene solution and being annealed at various temperatures. With the analysis of temperature dependence PL intensities, we conclude that PL emission around 680 nm at low temperature is due to intertain excimers instead of intrachain excitons for 450 K annealed film. On the other hand, this relative intensity difference is much smaller in both unannealed and 500 K annealed films, in which the morphology is amorphous and microcrystalline, respectively. We conclude that the interchain photoexcitations play crucial roles in the photophysics of MEH-PPV films. The further measurements on PIA spectrum of MEH-PPV films suggest that the interchain photoexciation is also important for the generation of triplet excitons.

  15. Naphthodipyrrolidone (NDP) based conjugated polymers with high electron mobility and ambipolar transport properties

    DOE PAGES

    Zhang, Haichang; Zhang, Shuo; Mao, Yifan; ...

    2017-05-12

    Two novel donor–acceptor π-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm2 V–1 s–1. The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. In conclusion, the polymer with NDP and bithiophenemore » units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.« less

  16. Distributed Feedback Lasers Made With Semiconducting Conjugated Polymers as the Gain Material

    NASA Astrophysics Data System (ADS)

    McGehee, Michael; Hide, Fumitomo; Diaz-Garcia, Maria; Schwartz, Benjamin; Moses, Daniel; Heeger, Alan

    1997-03-01

    We have reported that thin films of a variety of conjugated polymers exhibit stimulated emission when optically pumped with 10 nsec long 20 μJ/cm^2 pulses.^1 It was shown that thin (submicron) films cast on glass substrates form simple planar waveguides which allow the distance traveled by emitted photons in the gain material to exceed the gain length. These initial experiments showed that conjugated polymers are potentially useful as materials for solid-state lasers. Here we report the fabrication of distributed feedback lasers made with the conjugated polymer poly(2-butyl-5-(2-ethyl-hexyl)-1,4-phenylene vinylene) (BUEH-PPV) as the gain material. Initial results show that distributed feedback lowers the threshold for lasing by more than a factor of twenty to well below 1 μJ/cm^2 for 10 nsec pulses. ^1 Fumitomo Hide, Maria Diaz-Garcia, Benjamin J. Schwartz, Mats R. Andersson, Qibing Pei, Alan J. Heeger, RSemiconducting Polymers: A New Class of Solid-State Laser MaterialsS, Science, 273, 1996, 1833-35.

  17. Conjugated polymers/semiconductor nanocrystals hybrid materials--preparation, electrical transport properties and applications.

    PubMed

    Reiss, Peter; Couderc, Elsa; De Girolamo, Julia; Pron, Adam

    2011-02-01

    This critical review discusses specific preparation and characterization methods applied to hybrid materials consisting of π-conjugated polymers (or oligomers) and semiconductor nanocrystals. These materials are of great importance in the quickly growing field of hybrid organic/inorganic electronics since they can serve as active components of photovoltaic cells, light emitting diodes, photodetectors and other devices. The electronic energy levels of the organic and inorganic components of the hybrid can be tuned individually and thin hybrid films can be processed using low cost solution based techniques. However, the interface between the hybrid components and the morphology of the hybrid directly influences the generation, separation and transport of charge carriers and those parameters are not easy to control. Therefore a large variety of different approaches for assembling the building blocks--conjugated polymers and semiconductor nanocrystals--has been developed. They range from their simple blending through various grafting procedures to methods exploiting specific non-covalent interactions between both components, induced by their tailor-made functionalization. In the first part of this review, we discuss the preparation of the building blocks (nanocrystals and polymers) and the strategies for their assembly into hybrid materials' thin films. In the second part, we focus on the charge carriers' generation and their transport within the hybrids. Finally, we summarize the performances of solar cells using conjugated polymer/semiconductor nanocrystals hybrids and give perspectives for future developments.

  18. Donor–acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy† †Electronic supplementary information (ESI) available: Additional computational and experimental details, including the DNP sample preparation. See DOI: 10.1039/c7sc00053g Click here for additional data file.

    PubMed Central

    Chaudhari, Sachin R.; Broch, Katharina; Lesage, Anne; Lemaur, Vincent; Dudenko, Dmytro; Olivier, Yoann; Sirringhaus, Henning; Emsley, Lyndon; Grey, Clare P.

    2017-01-01

    Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor–acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT). Using conventional 1H and 13C solid-state MAS NMR coupled with density functional theory calculations and molecular dynamics simulations, we find that the bulk polymer adopts a highly planar backbone conformation with a laterally-shifted donor-on-acceptor stacking arrangement. DNP SENS enables acquisition of 13C NMR data for polymer films, where sensitivity is limiting owing to small sample volumes. The DNP signal enhancement enables a two-dimensional 1H–13C HETCOR spectrum to be recorded for a drop-cast polymer film, and a 13C CPMAS NMR spectrum to be recorded for a spin-coated thin-film with a thickness of only 400 nm. The results show that the same planar backbone structure and intermolecular stacking arrangement is preserved in the films following solution processing and annealing, thereby rationalizing the favourable device properties of DPP-DTT, and providing a protocol for the study of other thin film materials. PMID:28507688

  19. Structure and Conformation of Ionic Conjugated Polymers: Polydots

    NASA Astrophysics Data System (ADS)

    Osti, Naresh; Etampawala, Thusitha; Wijesinghe, Sidath; Perahia, Dvora

    2014-03-01

    Conjugated polymers confining into nano dimension form long-lived highly luminescent tunable organic particles of having enormous potential for intracellular imaging and drug delivery. Even though the chains are not in their thermodynamically stable conformation, the poly-dots remain stable over long period of times. Incorporation of ionic groups into conjugated polymers introduces a configuration control factor that impacts their conformation and their applications as luminescent probes. The current work investigates the structure and stability of poly-dots of di-alkoxy para polyphenyleneethynylene (PPE) conjugated polymer substituted with carboxylate side chain. Our small angle neutron scattering (SANS) studies have shown that ionic PPE forms spherical poly-dots in water. Ionic Poly-dots remain stable up to a temperature of 800C compare to neutral conjugated polymer poly dots. These polymer dots were allowed to assemble at a solid surface and observed by AFM which showed the nano aggregates of different sizes that assembled in different ways depending on the concentration and molecular parameters of the ionic PPEs used.

  20. Hybrid zinc oxide conjugated polymer bulk heterojunction solar cells.

    PubMed

    Beek, Waldo J E; Wienk, Martijn M; Kemerink, Martijn; Yang, Xiaoniu; Janssen, René A J

    2005-05-19

    Bulk heterojunction photovoltaic devices based on blends of a conjugated polymer poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) as electron donor and crystalline ZnO nanoparticles (nc-ZnO) as electron acceptor have been studied. Composite nc-ZnO:MDMO-PPV films were cast from a common solvent mixture. Time-resolved pump-probe spectroscopy revealed that a photoinduced electron transfer from MDMO-PPV to nc-ZnO occurs in these blends on a sub-picosecond time scale and produces a long-lived (milliseconds) charge-separated state. The photovoltaic effect in devices, made by sandwiching the active nc-ZnO:MDMO-PPV layer between charge-selective electrodes, has been studied as a function of the ZnO concentration and the thickness of the layer. We also investigated changing the degree and type of mixing of the two components through the use of a surfactant for ZnO and by altering the size and shape of the nc-ZnO particles. Optimized devices have an estimated AM1.5 performance of 1.6% with incident photon to current conversion efficiencies up to 50%. Photoluminescence spectroscopy, atomic force microscopy, and transmission electron microscopy have been used to gain insight in the morphology of these blends.

  1. Cyclodextrin insulation prevents static quenching of conjugated polymer fluorescence at the single molecule level.

    PubMed

    Thomsson, Daniel; Camacho, Rafael; Tian, Yuxi; Yadav, Dheerendra; Sforazzini, Giuseppe; Anderson, Harry L; Scheblykin, Ivan G

    2013-08-12

    Conjugated polymers (CPs) are promising materials for fluorescence imaging application. However, a significant problem in this field is the unexplained abnormally low fluorescence brightness (or number of fluorescence photons detected per one excitation photon) exhibited by most of CP single chains in solid polymer hosts. Here it is shown that this detrimental effect can be fully avoided for short chains of polyfluorene-bis-vinylphenylene (PFBV) embedded in a host polymer matrix of PMMA, if the conjugated backbone is insulated by cyclodextrin rings to form a polyrotaxane (PFBV-Rtx). Fluorescence kinetics and quantum yields are measured for the polymers in liquid solutions, pristine films, and solid PMMA blends. The fluorescence brightness of PFBV-Rtx single chains dispersed in a solid PMMA is very close to that expected for a chain with 100% fluorescence quantum yield, while the unprotected PFBV chains of the same length possess 4 times lower brightness. Despite this, the fluorescence decay kinetics are the same for both polymers, suggesting the presence of static or ultrafast fluorescence quenching in the unprotected polymer. About 80% of an unprotected PFBV chain is estimated to be completely quenched. The hypothesis is that the cyclodextrin rings prevent the quenching by working as 'bumpers' reducing the mechanical forces applied by the host polymer to the conjugated backbone and help retaining its conformational freedom. While providing a recipe for making CP fluorescence bright at the single-molecule level, these results identify a lack of fundamental understanding in the community of the influence of the environment on excited states in conjugated materials.

  2. Plasmonic-enhanced fluorescent conjugated polymer chemosensor for ultra-sensitive detection of nitroaromatic vapors

    NASA Astrophysics Data System (ADS)

    Darr, Charles Matthew

    Rapid degradation of fluorescent conjugated polymers in ambient conditions imposes severe restrictions on their utility for long-term, portable sensing applications. This dissertation discusses the combined use of low-density, ultra-thin oxide capping layers and plasmonic silver gratings as a means of improving the utility of fluorescent conjugated polymer ultra-thin films (<50 nm) for long-term, portable chem/bio sensing applications. Silver gratings produced by a low-cost micro-contact printing method enhanced emission of poly-[2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) by as much as 12-fold with respect to films on flat silver through a mechanism of surface plasmon-coupled emission, which directs specific emitted wavelengths toward the detection window of the fluorescence microscope. Addition of a low-density, ultra-thin silica capping layer (d = 5.07 nm, n = 1.38) improved MEH-PPV photostability significantly with respect to uncapped films under both short-term continuous illumination as well as long-term storage in dark, ambient air, while retaining a rapid quenching response to nitroaromatic vapors. Capped, plasmonic-enhanced MEH-PPV film showed a response to 2,4-dinitrotoluene vapor at a rate more than 7-fold faster than capped films on SiO2-coated silicon, attributed to a combination of sensitization effects of the silver on the conjugated polymer molecules in close proximity to the metal. Lateral diffusion of nitroaromatic vapor into the film is tracked by monitoring growth of quenched regions through fluorescence imaging. Most importantly, the devices recover fluorescence spontaneously on removal from the nitroaromatic vapor source, suggesting they could be used for long-term, real-time measurements of nitroaromatic vapors.

  3. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates.

    PubMed

    Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram

    2016-08-03

    We demonstrate that local and long-range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the substrate with solution-state disentanglement and preaggregation of P3HT in a θ solvent, leading to a very significant enhancement of the field effect carrier mobility. The preaggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of preaggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of preaggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to unaggregated polymer chains in the same conditions. Additional measurements reveal the combined preaggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known preaggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

  4. Conjugated ladder polymers by a cyclopentannulation polymerization

    DOE PAGES

    Bheemireddy, Sambasiva R.; Hautzinger, Matthew P.; Li, Tao; ...

    2017-04-03

    Here, we report a nontraditional synthesis of cyclopentafused-polycyclic aromatic hydrocarbon embedded ladder polymers using a palladium catalyzed cyclopentannulation polymerization followed by a cyclodehydrogenation reaction. Donor–acceptor type polymers containing a cyclopenta[hi]aceanthrylene acceptor groups can be synthesized by a palladium catalyzed copolymerization between 9,10-dibromoanthracene and a variety of bis(arylethynyl)arenes to give polymers with molecular weights (Mn) of 9–22 kDa. The bis(arylethynyl)arenes were composed of benzene, thiophene, or thieno[3,2-b]thiophene moieties, which provided access to a series of four donor–acceptor copolymers. The polymers were subjected to cyclodehydrogenation with FeCl3 to access rigid ladder type polymers with the conversion investigated by 13C NMR of isotopicallymore » labeled polymers. As a result, the ladder polymers possess broad UV–Vis absorptions and narrow optical band gaps of 1.17–1.29 eV and are p-type semiconductors in organic field effect transistors.« less

  5. Self-assembled breath figure arrays of conjugated conducting polymers for photovoltaic application

    NASA Astrophysics Data System (ADS)

    Routh, Prahlad Kumar; Venkatesh, T. A.; Cotlet, Mircea

    2014-03-01

    Ordered microporous polymer structures have potential application in catalysis, surface engineering and optoelectronics. The Breath Figure Technique (BFT) is a simple method of producing such ordered microporous structures. In this study BFT was applied to a series of commercial conjugated polymer polythiophene derivatives with varying side chain length (n =6,8,10,12). An in-depth study of processing parameters has been carried with the aim of controlling the morphology of the honeycomb film over large, PV relevant areas. Structural and spectroscopic characterization of honeycomb films were performed using Scanning Electron Microscopy (SEM), X-ray scattering, Fluorescence Lifetime Imaging (FLIM) and Spectroscopy. Blends of these polymers with a fullerene derivative, PCBM, were also subjected to BFT and characterized with similar methods to assess their potential use as active layers in PV solar cells. Center for Functional Nanomaterials, Brookhaven National Laboratory.

  6. Patterning of conjugated polymers for organic optoelectronic devices.

    PubMed

    Xu, Youyong; Zhang, Fan; Feng, Xinliang

    2011-05-23

    Conjugated polymers have been attracting more and more attention because they possess various novel electrical, magnetical, and optical properties, which render them useful in modern organic optoelectronic devices. Due to their organic nature, conjugated polymers are light-weight and can be fabricated into flexible appliances. Significant research efforts have been devoted to developing new organic materials to make them competitive with their conventional inorganic counterparts. It is foreseeable that when large-scale industrial manufacture of the devices made from organic conjugated polymers is feasible, they would be much cheaper and have more functions. On one hand, in order to improve the performance of organic optoelectronic devices, it is essential to tune their surface morphologies by techniques such as patterning. On the other hand, patterning is the routine requirement for device processing. In this review, the recent progress in the patterning of conjugated polymers for high-performance optoelectronic devices is summarized. Patterning based on the bottom-up and top-down methods are introduced. Emerging new patterning strategies and future trends for conventional patterning techniques are discussed.

  7. Recent Advances in Conjugated Polymer Materials for Disease Diagnosis.

    PubMed

    Lv, Fengting; Qiu, Tian; Liu, Libing; Ying, Jianming; Wang, Shu

    2016-02-10

    The extraordinary optical amplification and light-harvesting properties of conjugated polymers impart sensing systems with higher sensitivity, which meets the primary demands of early cancer diagnosis. Recent advances in the detection of DNA methylation and mutation with polyfluorene derivatives based fluorescence resonance energy transfer (FRET) as a means to modulate fluorescent responses attest to the great promise of conjugated polymers as powerful tools for the clinical diagnosis of diseases. To facilitate the ever-changing needs of diagnosis, the development of detection approaches and FRET signal analysis are highlighted in this review. Due to their exceptional brightness, excellent photostability, and low or absent toxicity, conjugated polymers are verified as superior materials for in-vivo imaging, and provide feasibility for future clinical molecular-imaging applications. The integration of conjugated polymers with clinical research has shown profound effects on diagnosis for the early detection of disease-related biomarkers, as well as in-vivo imaging, which leads to a multidisciplinary scientific field with perspectives in both basic research and application issues.

  8. Preparation of patterned ultrathin polymer films.

    PubMed

    Yang, Huige; Su, Meng; Li, Kaiyong; Jiang, Lei; Song, Yanlin; Doi, Masao; Wang, Jianjun

    2014-08-12

    Though patterned ultrathin polymer films (<100 nm) are of great importance in the fields of sensors and nanoelectronic devices, the fabrication of patterned ultrathin polymer films remains a great challenge. Herein, patterned ultrathin polymer films are fabricated facilely on hydrophobic substrates with different hydrophilic outline patterns by the pinning of three-phase contact lines of polymer solution on the hydrophilic outlines. This method is universal for most of the water-soluble polymers, and poly(vinyl alcohol) (PVA) has been selected as a model polymer due to its biocompatibility and good film-forming property. The results indicate that the morphologies of ultrathin polymer films can be precisely adjusted by the size of the hydrophilic outline pattern. Specifically, patterned hydrophilic outlines with sizes of 100, 60, and 40 μm lead to the formation of concave-shaped ultrathin PVA films, whereas uniform ultrathin PVA films are formed on 20 and 10 μm patterned substrates. The controllabilities of morphologies can be interpreted through the influences of the slip length and coffee ring effect. Theoretical analysis shows that when the size of the hydrophilic outline patterns is smaller than a critical value, the coffee ring effect disappears and uniform patterned ultrathin polymer films can be formed for all polymer concentrations. These results provide an effective methodology for the fabrication of patterned ultrathin polymer films and enhance the understanding of the coffee ring effect.

  9. Role of Aggregates in the Luminescence Decay Dynamics of Conjugated Polymers.

    PubMed

    Chakraborty, Rajarshi; Rothberg, Lewis J

    2016-02-04

    Fluorescence quantum yields of conjugated polymer films are systematically lower than their counterparts in dilute solution. Films also exhibit a long "temporal tail" in their fluorescence decay dynamics not present in solution. We study the spectroscopy, excitation wavelength dependence, temperature dependence, and electric field quenching of the temporal tail of the photoluminescence in MEH-PPV on a nanosecond time scale to elucidate the relationship between those observations. We conclude that the tail represents emission from H-like aggregated regions in the polymer. Using a simple model of the photophysics, we estimate the formation yield of the aggregates responsible for the tail emission to be <20% so that they cannot account for the large reduction in fluorescence observed in densely packed films relative to that in solution.

  10. Electroactive polymer-peptide conjugates for adhesive biointerfaces.

    PubMed

    Maione, Silvana; Gil, Ana M; Fabregat, Georgina; Del Valle, Luis J; Triguero, Jordi; Laurent, Adele; Jacquemin, Denis; Estrany, Francesc; Jiménez, Ana I; Zanuy, David; Cativiela, Carlos; Alemán, Carlos

    2015-10-15

    Electroactive polymer-peptide conjugates have been synthesized by combining poly(3,4-ethylenedioxythiophene), a polythiophene derivative with outstanding properties, and an Arg-Gly-Asp (RGD)-based peptide in which Gly has been replaced by an exotic amino acid bearing a 3,4-ethylenedioxythiophene ring in the side chain. The incorporation of the peptide at the ends of preformed PEDOT chains has been corroborated by both FTIR and X-ray photoelectron spectroscopy. Although the morphology and topology are not influenced by the incorporation of the peptide at the ends of PEDOT chains, this process largely affects other surface properties. Thus, the wettability of the conjugates is considerably higher than that of PEDOT, independently of the synthetic strategy, whereas the surface roughness only increases when the conjugate is obtained using a competing strategy (i.e. growth of the polymer chains against termination by end capping). The electrochemical activity of the conjugates has been found to be higher than that of PEDOT, evidencing the success of the polymer-peptide links designed by chemical similarity. Density functional theory calculations have been used not only to ascertain the conformational preferences of the peptide but also to interpret the electronic transitions detected by UV-vis spectroscopy. Electroactive surfaces prepared using the conjugates displayed the higher bioactivities in terms of cell adhesion, with the relative viabilities being dependent on the roughness, wettability and electrochemical activity of the conjugate. In addition to the influence of the peptide fragment in the initial cell attachment and subsequent cell spreading and survival, the results indicate that PEDOT promotes the exchange of ions at the conjugate-cell interface.

  11. Dirac Cones in two-dimensional conjugated polymer networks

    NASA Astrophysics Data System (ADS)

    Adjizian, Jean-Joseph; Briddon, Patrick; Humbert, Bernard; Duvail, Jean-Luc; Wagner, Philipp; Adda, Coline; Ewels, Christopher

    2014-12-01

    Linear electronic band dispersion and the associated Dirac physics has to date been limited to special-case materials, notably graphene and the surfaces of three-dimensional (3D) topological insulators. Here we report that it is possible to create two-dimensional fully conjugated polymer networks with corresponding conical valence and conduction bands and linear energy dispersion at the Fermi level. This is possible for a wide range of polymer types and connectors, resulting in a versatile new family of experimentally realisable materials with unique tuneable electronic properties. We demonstrate their stability on substrates and possibilities for doping and Dirac cone distortion. Notably, the cones can be maintained in 3D-layered crystals. Resembling covalent organic frameworks, these materials represent a potentially exciting new field combining the unique Dirac physics of graphene with the structural flexibility and design opportunities of organic-conjugated polymer chemistry.

  12. Magnetic conjugated polymer nanoparticles as bimodal imaging agents.

    PubMed

    Howes, Philip; Green, Mark; Bowers, Alex; Parker, David; Varma, Gopal; Kallumadil, Mathew; Hughes, Mary; Warley, Alice; Brain, Anthony; Botnar, Rene

    2010-07-21

    Hybrid nanoparticles which incorporate multiple functionalities, such as fluorescence and magnetism, can exhibit enhanced efficiency and versatility by performing several tasks in parallel. In this study, magnetic-fluorescent semiconductor polymer nanospheres (MF-SPNs) have been synthesized by encapsulation of hydrophobic conjugated polymers and iron oxide nanoparticles in phospholipid micelles. Four fluorescent conjugated polymers were used, yielding aqueous dispersions of nanoparticles which emit across the visible spectrum. The MF-SPNs were shown to be magnetically responsive and simultaneously fluorescent. In MRI studies, they were seen to have a shortening effect on the transverse T(2)* relaxation time, which demonstrates their potential as an MR contrast agent. Finally, successful uptake of the MF-SPNs by SH-SY5Y neuroblastoma cells was demonstrated, and they were seen to behave as bright and stable fluorescent markers. There was no evidence of toxicity or adverse affect on cell growth.

  13. Photocurrent generation in carbon nitride and carbon nitride/conjugated polymer composites.

    PubMed

    Byers, Joshua C; Billon, Florence; Debiemme-Chouvy, Catherine; Deslouis, Claude; Pailleret, Alain; Semenikhin, Oleg A

    2012-09-26

    The semiconductor and photovoltaic properties of carbon nitride (CNx) thin films prepared using a reactive magnetron cathodic sputtering technique were investigated both individually and as composites with an organic conjugated polymer, poly(2,2'-bithiophene) (PBT). The CNx films showed an increasing thickness as the deposition power and/or nitrogen content in the gas mixture increase. At low nitrogen content and low deposition power (25-50 W), the film structure was dominated by the abundance of the graphitic sp(2) regions, whereas at higher nitrogen contents and magnetron power CNx films started to demonstrate semiconductor properties, as evidenced by the occurrence of photoconductivity and the development of a space charge region. However, CNx films alone did not show any reproducible photovoltaic properties. The situation changed, however, when CNx was deposited onto conjugated PBT substrates. In this configuration, CNx was found to function as an acceptor material improving the photocurrent generation both in solution and in solid state photovoltaic devices, with the external quantum efficiencies reaching 1% at high nitrogen contents. The occurrence of the donor-acceptor charge transfer was further evidenced by suppression of the n-doping of the PBT polymer by CNx. Nanoscale atomic force microscopy (AFM) and current-sensing AFM data suggested that CNx may form a bulk heterojunction with PBT.

  14. Synthesis of biotinylated aldehyde polymers for biomolecule conjugation.

    PubMed

    Alconcel, Steevens N S; Kim, Sung Hye; Tao, Lei; Maynard, Heather D

    2013-06-25

    Biotinylated polymers with side-chain aldehydes were prepared for use as multifunctional scaffolds. Two different biotin-containing chain transfer agents (CTAs) and an aldehyde-containing monomer, 6-oxohexyl acrylate (6OHA), are synthesized. Poly(ethylene glycol) methyl ether acrylate (PEGA) and 6OHA are copolymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of the biotinylated CTAs. The resulting polymers are analyzed by GPC and(1) H NMR spectroscopy. The polymer end groups contained a disulfide bond, which could be readily reduced in solution to remove the biotin. Reactivity of the aldehyde side chains is demonstrated by oxime and hydrazone formation at the polymer side chains, and conjugate formation of fluorescently labeled polymers with streptavidin is investigated by gel electrophoresis.

  15. Recent Advances in Polymer Organic Light-Emitting Diodes (PLED) Using Non-conjugated Polymers as the Emitting Layer and Contrasting Them with Conjugated Counterparts

    NASA Astrophysics Data System (ADS)

    Wong, Michael Y.

    2017-07-01

    Polymer organic light-emitting diodes (PLED) are one of the most studied subjects in flexible electronics thanks to their economical wet fabrication procedure for enhanced price advantage of the product device. In order to optimize PLED efficiency, correlating the polymer structure with the device performance is essential. An important question for the researchers in this field is whether the polymer backbone is conjugated or not as it affects the device performance. In this review, recent advances in non-conjugated polymers employed as the emitting layer in PLED devices are first discussed, followed by their contrast with the conjugated counterparts in terms of polymer synthesis, sample quality, physical properties and device performances. Such comparison between conjugated and non-conjugated polymers for PLED applications is rarely attempted, and; hence, this review shall provide a useful insight of emitting polymers employed in PLEDs.

  16. Synthesis of Conjugated Polymers via Polymer Elimination Reactions.

    DTIC Science & Technology

    1987-04-16

    Publication DTIC in GtECTE Chemical Reactions on PolymerS. J.L. Benham and J.F. Kinstle (eds.) MAY12987 American Chem. Soc. Symp. Series, 1987 April 16...FROM TO April 16, 19M7 16. SUPPLEMENTARY NOTATION To be published in: "Chemical Reactions on Polymers," J.L. Benham and J.F. Kinstle (eds.) ACS Sp...I % %.......Z~ ....Z.. ... e. . ,e In: Chemical Reactions on Polymers, J.L. Benham and J.F. Kinstle (eds.), Am. Chem. Soc. Symp. Series vol

  17. Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

    NASA Astrophysics Data System (ADS)

    Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

    2016-03-01

    The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity.

  18. Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

    PubMed Central

    Botiz, Ioan; Stingelin, Natalie

    2014-01-01

    It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. PMID:28788568

  19. Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

    PubMed Central

    Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

    2016-01-01

    The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity. PMID:26940513

  20. Hierarchical assembly of branched supramolecular polymers from (cyclic Peptide)-polymer conjugates.

    PubMed

    Koh, Ming Liang; Jolliffe, Katrina A; Perrier, Sébastien

    2014-11-10

    We report the synthesis and assembly of (N-methylated cyclic peptide)-polymer conjugates for which the cyclic peptide is attached to either the α- or both α- and ω- end groups of a polymer. A combination of chromatographic, spectroscopic, and scattering techniques reveals that the assembly of the conjugates follows a two-level hierarchy, initially driven by H-bond formation between two N-methylated cyclic peptides, followed by unspecific, noncovalent aggregation of this peptide into small domains that behave as branching points and lead to the formation of branched supramolecular polymers.

  1. Morphology and structure control of luminescence in light-emitting conjugated polymers

    NASA Astrophysics Data System (ADS)

    Piskun, Nadezhda Vasilievna

    2001-06-01

    A basic understanding of the physics processes in luminescent conjugated polymers is necessary both for improving electro-luminescent properties of the polymers and for creating fundamental theoretical models that can explain the underlying electronic structure of the polymers. Pyridine-based polymers such as poly(pyridyl vinylene phenylene vinylene) (PPyVPV) and substituted polydiphenylacetylene (PDPAs) already have been used in various light-emitting devices (LED) and show a spectral narrowing, which can lead to the creation of polymer- based lasers. We investigated the role of different side groups and oxygen bridges around phenyl rings on the pyridine and thiophene-based polymer films and solutions. The luminescence from individual polymer chains in solution is molecular and characterized by both very high quantum efficiency (around 80%) and a single-exponential decay. The luminescence from film samples is structureless, with strong spectral diffusion on a nanosecond time scale and small quantum efficiency (around 10%). The difference in the photoluminescence in solutions and films can be explained using torsion angle calculations and aggregation formation in films. By introducing oxygen bridges (straps) it is possible to keep polymer chains well separated and thus reduce the aggregation formation. Strapped film samples have narrow absorption and emission features and show small spectral diffusion. We studied the role of different substituents in PDPA systems. The absorption edge of PDPA varies with substituents. Both PDPA with n-Butyl and carbazole side groups have emission due to excitons on the -(C=C)- π backbone with characteristic lifetimes of a couple hundreds picoseconds, which is in agreement with a ultrafast time-resolved data. PDPA with carbazole side group (PDPA-Cz) has greater spectral shift than PDPA with n-Butyl (PDPA-nBu) due to variations in conjugated lengths. The well-known polymer polyvinylcarbazole (PVK) was investigated. The

  2. Ultrathin Polymer Films, Patterned Arrays, and Microwells

    NASA Astrophysics Data System (ADS)

    Yan, Mingdi

    2002-05-01

    The ability to control and tailor the surface and interface properties of materials is important in microelectronics, cell growth control, and lab-on-a-chip devices. Modification of material surfaces with ultrathin polymer films is attractive due to the availability of a variety of polymers either commercially or by synthesis. We have developed two approaches to the attachment of ultrathin polymer films on solid substrates. In the first method, a silane-functionalized perfluorophenyl azide (PFPA-silane) was synthesized and used to covalently immobilize polymer thin films on silicon wafers. Silanization of the wafer surface with the PFPA-silane introduced a monolayer of azido groups which in turn covalently attached the polymer film by way of photochemically initiated insertion reactions. The thickness of the film could be adjusted by the type and the molecular weight of the polymer. The method is versatile due to the general C-H and/or N-H insertion reactions of crosslinker; and therefore, no specific reactive functional groups on the polymers are required. Using this method, a new type of microwell array was fabricated from covalently immobilized polymer thin films on flat substrates. The arrays were characterized with AFM, XPS, and TOF-SIMS. The second method describes the attachment of polymer thin films on solid substrates via UV irradiation. The procedure consisted of spin-coating a polymer film and irradiating the film with UV light. Following solvent extraction, a thin film remained. The thickness of the film, from a few to over a hundred nanometers, was controlled by varying solution concentration and the molecular weight of the polymer.

  3. A self-assembled ultrathin crystalline polymer film for high performance phototransistors.

    PubMed

    Li, Hui; Wu, Yishi; Wang, Xuedong; Kong, Qinghua; Fu, Hongbing

    2014-09-28

    The π-conjugated polymer, PQBOC8, can be easily assembled into a large-area crystalline ultrathin film at the CHCl3/water interface. A phototransistor based on this ultrathin film showed a large photoresponsivity of 970 A W(-1), and a photocurrent/dark current ratio of 1.36 × 10(4) under a very low white light irradiation.

  4. Highly emissive PEG-encapsulated conjugated polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Yuqiong; Liu, Jie; Liu, Bin; Tomczak, Nikodem

    2012-08-01

    A novel bioimaging probe based on a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,1,3-benzoxadiazole) (PFBD), is demonstrated. Transfer of the hydrophobic polymer into water using a short chain poly(ethylene glycol) (PEG) resulted in conjugated polymer nanoparticles (PEG-PFBD) with a fluorescence quantum yield of 46%. The PEG-PFBD nanoparticles possessed several desirable structural and photophysical properties, such as colloidal stability in a broad range of pH values, sub-20 nm particle size, the presence of surface chemical functionality, as well as desirable excitation and emission spectra, for bioimaging applications. PEG-PFBD nanoparticles were conjugated with cyclic RGDfK targeting peptide for labeling of membrane αVβ3 integrin receptors on live HT-29 adenocarcinoma cells. Single nanoparticle microscopy revealed that the PEG-capped PFBD nanoparticles exhibit at least ten times higher emitted photon counts than single quantum dots (QD655) of comparable size. In addition, Fluorescence Lifetime Imaging Microscopy (FLIM) of single PEG-PFBD nanoparticles revealed that the nanoparticles display a clearly resolvable single nanoparticle fluorescence lifetime.A novel bioimaging probe based on a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,1,3-benzoxadiazole) (PFBD), is demonstrated. Transfer of the hydrophobic polymer into water using a short chain poly(ethylene glycol) (PEG) resulted in conjugated polymer nanoparticles (PEG-PFBD) with a fluorescence quantum yield of 46%. The PEG-PFBD nanoparticles possessed several desirable structural and photophysical properties, such as colloidal stability in a broad range of pH values, sub-20 nm particle size, the presence of surface chemical functionality, as well as desirable excitation and emission spectra, for bioimaging applications. PEG-PFBD nanoparticles were conjugated with cyclic RGDfK targeting peptide for labeling of membrane αVβ3 integrin receptors on live HT-29 adenocarcinoma cells. Single

  5. Liquid film/polymer interfaces

    SciTech Connect

    Allara, David L.

    2003-06-12

    The objectives were: (1) Through experimental studies, advance the fundamental understanding of the principles that govern adsorption and wetting phenomena at polymer and organic surfaces. (2) Establish a firm scientific basis for improving the design of coatings for metal fin cooling surfaces used to control the wetting of water condensate for optimum energy efficiency. Several important findings were: (1) water adsorbed at hydrophobic surfaces has a liquid-like structure, in contrast to the generally held view of an ordered structure; (2) Correlations of large amounts of contact angle wetting data of grafted alkyl chain compounds showed a distinct link between the contact angle and the conformational ordering of the chains; (3) water adsorption at long chain alkysiloxane films showed a strong pH dependence on the film stability, which can be attributed to interfacial chemical effects on the siloxane network.

  6. Designing dapsone polymer conjugates for controlled drug delivery.

    PubMed

    Rojo, Luis; Fernandez-Gutierrez, Mar; Deb, Sanjukta; Stevens, Molly M; San Roman, Julio

    2015-11-01

    Polymer-drug conjugates have significantly influenced polymer therapeutics over the last decade via controlled pharmacokinetics. Dapsone (4,4'-diamino diphenylsulphone) is not only widely used in the treatment of leprosy but forms an essential component in the treatment of autoimmune inflammatory diseases and malaria. However, its low bioavailability and non-specific distribution in the body leads to absorption throughout organs including skin, liver, and kidneys that can cause serious side effects. Thus, in this study we report the synthesis of polymer-drug conjugates of dapsone covalently bonded to macromolecular chains towards the development of new bioactive polymeric formulations with anti-inflammatory properties. Dapsone was functionalised with an acrylic moiety in which the acrylamide residue was directly bonded to one of the aromatic rings of dapsone. This functionalisation yielded an unsymmetrical dapsone methacrylamide (DapMA) structure, which on free radical polymerisation and co-polymerisation with HEMA yielded polymers of hydrocarbon macromolecules with pendant dapsone units. Thermal and size-exclusion chromatographic analysis revealed an increase in thermal stabilisation of the homopolymer (p(DapMA)) in comparison to the copolymer (p(Dap-co-HEMA)) with relatively high average molecular weight. The polymer conjugates exhibited high stability with low dapsone release from the polymeric backbone due to hydrolysis. However, a significant anti-inflammatory activity in a nitric oxide inhibition assay confirmed that this property was the consequence of only the macromolecular composition and not related to the release of low molecular weight compounds. Thus, the conjugation of dapsone to macromolecular systems provides a synthetic route to incorporate this drug into polymeric systems, facilitating their development into new anti-inflammatory therapies. The dapsone-conjugated methacrylic monomer and polymer derivatives with anti-inflammatory properties

  7. Glass transition dynamics and charge carrier mobility in conjugated polyfluorene thin films

    NASA Astrophysics Data System (ADS)

    Qin, Hui; Liu, Dan; Wang, Tao

    Conjugated polymers are commonly used in organic optoelectronic devices, e.g. organic photovoltaics (OPVs), light-emitting diodes (LEDs) and field effect transistors (FETs). In these devices, the conjugated polymers are prepared as thin films with thicknesses in the range of tens to hundreds of nanometers, and are interfaced with different function layers made from organic or inorganic materials. We have studied the glass transition temperature (Tg) of poly(9, 9-dioctylfluorene)-co-N-(1, 4-butylphenyl)diphenylamine) (TFB) thin films supported on different substrates, as well as their SCLC charge carrier mobility in photodiodes. Both Monotonic and non-monotonic Tg deviations are observed in TFB thin films supported on Si/SiOx and PEDOT:PSS, respectively. With low to moderate thermal crosslinking, the thickness dependent Tg deviation still exists, which diminishes in TFB films with a high crosslinking degree. The vertical charge carrier mobility of TFB thin films extracted from the SCLC measurements is found increase with film thickness, a value increases from 1 to 50 x 10-6 cm2 V-1 s-1 in the thickness range from 15 to 180 nm. Crosslinking was found to reduce the carrier mobility in TFB thin films. The Tg deviations are also discussed using the classic layered models in the literature. Our results provide a precise guide for the fabrication and design of high performance optoelectronic devices.

  8. Formation and evolution dynamics of bipolarons in conjugated polymers.

    PubMed

    Di, B; Meng, Y; Wang, Y D; Liu, X J; An, Z

    2011-02-10

    Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), we analyze the scattering and combination in conjugated polymers of two polarons with the same charges and parallel or antiparallel spins using a nonadiabatic evolution method. Results show that collisions between the two same charge polarons with parallel spin are essentially elastic due to strong Pauli repulsion, whereas the two same charge polarons with antiparallel spins can combine into a singlet bipolaronic state. The dynamics of bipolarons on two coupled polymer chains and at the interface of a polymer/polymer heterojunction are discussed in detail. This knowledge will serve to understand the dynamics of the system when many polarons are created in the system, e.g., by electroluminescence.

  9. Electronic and optical excitations in crystalline conjugated polymers

    NASA Astrophysics Data System (ADS)

    van der Horst, J.-W.; Bobbert, P. A.; Michels, M. A.

    2002-07-01

    We calculate the electronic and optical excitations of crystalline polythiophene and polyphenylenevinylene, using the GW approximation for the electronic self-energy and including excitonic effects by solving the electron-hole Bethe-Salpeter equation. We compare with our earlier calculations on an isolated polythiophene chain and polymer chains embedded in a dielectric medium. Surprisingly, we find for the crystalline calculations optical gaps and exciton binding energies that are significantly smaller than present experimental values. We attribute the disagreement to the fact that the quantum-mechanical coherence between polymer chains, present in the calculations, is absent in most experimental situations. We discuss possible reasons for this absence. Our general conclusion is that the picture of a polymer chain in a dielectric medium is most appropriate in describing the present experimental data on electronic and optical excitations in conjugated polymers.

  10. Conformation sensitive charge transport in conjugated polymers

    SciTech Connect

    Mattias Andersson, L.; Hedström, Svante; Persson, Petter

    2013-11-18

    Temperature dependent charge carrier mobility measurements using field effect transistors and density functional theory calculations are combined to show how the conformation dependent frontier orbital delocalization influences the hole- and electron mobilities in a donor-acceptor based polymer. A conformationally sensitive lowest unoccupied molecular orbital results in an electron mobility that decreases with increasing temperature above room temperature, while a conformationally stable highest occupied molecular orbital is consistent with a conventional hole mobility behavior and also proposed to be one of the reasons for why the material works well as a hole transporter in amorphous bulk heterojunction solar cells.

  11. Characterization of naproxen-polymer conjugates for drug-delivery.

    PubMed

    Forte, Gianpiero; Chiarotto, Isabella; Giannicchi, Ilaria; Loreto, Maria Antonietta; Martinelli, Andrea; Micci, Roberta; Pepi, Federico; Rossi, Serena; Salvitti, Chiara; Stringaro, Annarita; Tortora, Luca; Vecchio Ciprioti, Stefano; Feroci, Marta

    2016-01-01

    The synthesis and the characterization of three new naproxen decorated polymers are described. A versatile and general approach is employed to link the drug to polymers, affording the derivatives with a very high degree of purity. The release of the drug from the conjugates proved to be exceptionally slow, even in acidic aqueous media, and the kinetic of the process seems to be triggered by their solubility in water. On the other hand, the interesting outcome of the first ex vivo drug release experiments on human blood samples makes this preliminary study valuable for future investigations on the use of these polymeric prodrugs in in vivo treatment of inflammatory states.

  12. Predicting polarizabilities and lifetimes of excitons on conjugated polymer chains

    NASA Astrophysics Data System (ADS)

    van der Horst, J.-W.; Bobbert, P. A.; de Jong, P. H. L.; Michels, M. A. J.; Siebbeles, L. D. A.; Warman, J. M.; Gelinck, G. H.; Brocks, G.

    2001-02-01

    The properties of excitons on three different conjugated polymers in solution are investigated both experimentally and theoretically. The theoretical description of the excitons is obtained by solving the electron-hole Bethe-Salpeter equation (BSE) for the polymers, starting from a calculation within density-functional theory. The calculated radiative lifetimes and polarizabilities of the excitons are compared with experimental results from time-resolved fluorescence decay and flash-photolysis microwave conductivity measurements. The quantitative agreement demonstrates the predictive power of the theoretical approach.

  13. Photon Harvesting in Conjugated Polymer-Based Functional Nanoparticles.

    PubMed

    Jana, Bikash; Ghosh, Arnab; Patra, Amitava

    2017-09-21

    The design of new generation light-harvesting systems based on conjugated polymer nanoparticles (PNPs) is an emerging field of research to convert solar energy into renewable energy. In this Perspective, we focus on the understanding of the light harvesting processes like exciton dynamics, energy transfer, antenna effect, charge carrier dynamics, and other related processes of conjugated polymer-based functional nanomaterials. Spectroscopic investigations unveil the rotational dynamics of the dye molecules inside of PNPs and exciton dynamics of the self-assembled structures. A detailed understanding of the cascade energy transfer for white light and singlet oxygen generation in multiple fluorophores containing a PNP system by time-resolved spectroscopy is highlighted. Finally, ultrafast spectroscopic investigations provide direct insight into the impacts of electron and hole transfer at the interface in the hybrid materials for photocatalysis and photocurrent generation to construct efficient light-harvesting systems.

  14. Highly stretchable polymer semiconductor films through the nanoconfinement effect.

    PubMed

    Xu, Jie; Wang, Sihong; Wang, Ging-Ji Nathan; Zhu, Chenxin; Luo, Shaochuan; Jin, Lihua; Gu, Xiaodan; Chen, Shucheng; Feig, Vivian R; To, John W F; Rondeau-Gagné, Simon; Park, Joonsuk; Schroeder, Bob C; Lu, Chien; Oh, Jin Young; Wang, Yanming; Kim, Yun-Hi; Yan, He; Sinclair, Robert; Zhou, Dongshan; Xue, Gi; Murmann, Boris; Linder, Christian; Cai, Wei; Tok, Jeffery B-H; Chung, Jong Won; Bao, Zhenan

    2017-01-06

    Soft and conformable wearable electronics require stretchable semiconductors, but existing ones typically sacrifice charge transport mobility to achieve stretchability. We explore a concept based on the nanoconfinement of polymers to substantially improve the stretchability of polymer semiconductors, without affecting charge transport mobility. The increased polymer chain dynamics under nanoconfinement significantly reduces the modulus of the conjugated polymer and largely delays the onset of crack formation under strain. As a result, our fabricated semiconducting film can be stretched up to 100% strain without affecting mobility, retaining values comparable to that of amorphous silicon. The fully stretchable transistors exhibit high biaxial stretchability with minimal change in on current even when poked with a sharp object. We demonstrate a skinlike finger-wearable driver for a light-emitting diode. Copyright © 2017, American Association for the Advancement of Science.

  15. Functional Films from Silica/Polymer Nanoparticles

    PubMed Central

    Ribeiro, Tânia; Baleizão, Carlos; Farinha, José Paulo S.

    2014-01-01

    High performance functional coatings, based on hybrid organic/inorganic materials, are being developed to combine the polymer flexibility and ease of processing with the mechanical properties and versatility of inorganic materials. By incorporating silica nanoparticles (SiNPs) in the polymeric matrices, it is possible to obtain hybrid polymer films with increased tensile strength and impact resistance, without decreasing the flexural properties of the polymer matrix. The SiNPs can further be used as carriers to impart other functionalities (optical, etc.) to the hybrid films. By using polymer-coated SiNPs, it is possible to reduce particle aggregation in the films and, thus, achieve more homogeneous distributions of the inorganic components and, therefore, better properties. On the other hand, by coating polymer particles with silica, one can create hierarchically structured materials, for example to obtain superhydrophobic coatings. In this review, we will cover the latest developments in films prepared from hybrid polymer/silica functional systems. PMID:28788655

  16. Conjugated polymer composite nanoparticles by rapid mixing.

    PubMed

    Jung, Christoph; de Roo, Tjaard; Mecking, Stefan

    2014-12-01

    Composite nanoparticles from poly[(9,9-di-n-octylfluoren-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT) and poly(9,9-di-n-hexylfluoren-2,7-diyl) (PF) with embedded inorganic nanoparticles (TiO2 , CdSe, and CdSe/CdS) are prepared through kinetic trapping by rapid turbulent mixing in a multi-inlet vortex mixer without the need for polymer functionalization. High contents of inorganic materials up to 50-60 wt% are realized for all composites. The influence of flow ratios, sodium dodecyl sulfate (SDS) concentration, and absolute flow rates on the particle size and morphology is studied. High water-to-THF ratios and high total flow rates around 2 m s(-1) yield particle sizes below 50 nm. By adjusting these parameters, controlled particle sizes between 30 to several hundred nanometers are obtained. Composite particles from CdSe/CdS and F8BT or PF show a strong quenching of the polymer emission and near exclusive emission from the inorganic nanocrystal, which indicates an efficient energy transfer with fluorescence quantum yields of 23% for the F8BT/CdSe/CdS composites and 21% for the PF/CdSe/CdS composites. The dispersions are colloidally stable for several months.

  17. High temperature polymer dielectric film insulation

    NASA Technical Reports Server (NTRS)

    Jones, Robert J.

    1994-01-01

    PFPI polymers were invented in the late 1970's. Assessment of emerging requirements has dictated that 300 C performance is the goal for next generation wire insulation. TRW PFPI as superior 300 C polymer candidates is presented. Included is a comparison of promising PFPI film properties with Kapton. Also included are the promising bulk polymer or coating properties.

  18. Ultrafast polarisation spectroscopy of photoinduced charges in a conjugated polymer

    SciTech Connect

    Bakulin, A A; Loosdrecht, P van; Pshenichnikov, M S; Parashchuk, D Yu

    2009-07-31

    Tunable optical parametric generators and amplifiers (OPA), proposed and developed by Akhmanov and his colleagues, have become the working horses in exploration of dynamical processes in physics, chemistry, and biology. In this paper, we demonstrate the possibility of using ultrafast polarisation-sensitive two-colour spectroscopy, performed with a set of two OPAs, to study charge photogeneration and transport in conjugated polymers and their donor-acceptor blends. (special issue devoted to the 80th birthday of S.A. Akhmanov)

  19. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, Kevin M.; Watson, Lloyd D.; McAtee, Richard E.; Ploger, Scott A.

    1993-01-01

    A method of forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous.

  20. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, K.M.; Watson, L.D.; McAtee, R.E.; Ploger, S.A.

    1993-10-12

    A method is described for forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous. 4 figures.

  1. Accurate Force Field Development for Modeling Conjugated Polymers.

    PubMed

    DuBay, Kateri H; Hall, Michelle Lynn; Hughes, Thomas F; Wu, Chuanjie; Reichman, David R; Friesner, Richard A

    2012-11-13

    The modeling of the conformational properties of conjugated polymers entails a unique challenge for classical force fields. Conjugation imposes strong constraints upon bond rotation. Planar configurations are favored, but the concomitantly shortened bond lengths result in moieties being brought into closer proximity than usual. The ensuing steric repulsions are particularly severe in the presence of side chains, straining angles, and stretching bonds to a degree infrequently found in nonconjugated systems. We herein demonstrate the resulting inaccuracies by comparing the LMP2-calculated inter-ring torsion potentials for a series of substituted stilbenes and bithiophenes to those calculated using standard classical force fields. We then implement adjustments to the OPLS-2005 force field in order to improve its ability to model such systems. Finally, we show the impact of these changes on the dihedral angle distributions, persistence lengths, and conjugation length distributions observed during molecular dynamics simulations of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) and poly 3-hexylthiophene (P3HT), two of the most widely used conjugated polymers.

  2. Direct (Hetero)arylation Polymerization: Simplicity for Conjugated Polymer Synthesis.

    PubMed

    Pouliot, Jean-Rémi; Grenier, François; Blaskovits, J Terence; Beaupré, Serge; Leclerc, Mario

    2016-11-23

    Direct (hetero)arylation polymerization (DHAP) has recently been established as an environmentally benign method for the preparation of conjugated polymers. This synthetic tool features the formation of C-C bonds between halogenated (hetero)arenes and simple (hetero)arenes with active C-H bonds, thereby circumventing the preparation of organometallic derivatives and decreasing the overall production cost of conjugated polymers. Since its inception, selectivity and reactivity of DHAP procedures have been improved tremendously through the careful scrutinity of polymerization outcomes and the fine-tuning of reaction conditions. A broad range of monomers, from simple arenes to complex functionalized heteroarenes, can now be readily polymerized. The successful application of DHAP now leads to nearly defect-free conjugated polymers possessing comparable, if not slightly better, characteristics than their counterparts prepared using classical cross-coupling methods. This comprehensive review describes the mechanisms involved in this process from experimental and theoretical standpoints, presents an up-to-date compendium of materials obtained by this means, and exposes its current limitations and challenges.

  3. Molecules with enhanced electronic polarizabilities based on defect-like states in conjugated polymers

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor)

    1991-01-01

    Highly conjugated organic polymers typically have large non-resonant electronic susceptibilities, which give the molecules unusual optical properties. To enhance these properties, defects are introduced into the polymer chain. Examples include light doping of the conjugated polymer and synthesis, conjugated polymers which incorporate either electron donating or accepting groups, and conjugated polymers which contain a photoexcitable species capable of reversibly transferring its electron to an acceptor. Such defects in the chain permit enhancement of the second hyperpolarizability by at least an order of magnitude.

  4. Triplet-polaron quenching in conjugated polymers.

    PubMed

    Hertel, D; Meerholz, K

    2007-10-25

    We studied the triplet-polaron quenching in a platinum(II) porphyrin- (PtOEP-) doped polyspirobifluorene (PSF-TAD) copolymer. The copolymer contains a hole-transporting phenylenediamine unit (TAD) as a comonomer. Triplet-polaron quenching was probed by the change in PtOEP phosphorescence lifetime under an applied voltage in a unipolar device. The charge-induced reduction of the optically excited lifetime of PtOEP is one-third for the highest applied bias. The charge density can be obtained from current-voltage characteristics in the space-charge-limited (SCL) regime. The obtained hole mobility under SCL conditions is (7 +/- 2) x 10(-5) cm(2)/(V s). This result is in accord with recent mobility measurements of the time-of-flight mobility in our polymer. The triplet-polaron recombination constant was evaluated to be (4 +/- 1) x 10(-13) cm(3)/s, implying a triplet-polaron interaction radius of 2 x 10(-10) m. The results show that triplet-polaron annihilation cannot be neglected in device models for phosphorescent light-emitting diodes.

  5. Conjugation length polydispersity and its effect on charge transport in conjugated polymer-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Menon, Anoop

    Conjugated polymers have immense potential for optoelectronic and display applications such as light emitting diodes (LEDs). Molecular weight distribution is a parameter intrinsic to all polymers. Yet it's effect on the LED application is previously unexplored. To study this effect, we synthesized a pentamer and nonamer of dialkoxy (p-phenylenevinylene) as well as dialkoxy poly(p-phenylenevinylene (PPV). By blending these materials we were able to simulate the polydispersity in conjugation length inherent in all polymers and systematically probe it's importance to LED performance. By mixing a low molecular weight dialkoxy-PPV or a nonamer of this PPV into a matrix of the pentamer, we were able to simulate the effect that a small concentration of low bandgap, highly conjugated segments, would have on PL and EL efficiency. The PL quantum efficiency was unaffected by the low bandgap fraction. EL was, however, dramatically impacted, being reduced by 50 to 70%. Based on this knowledge, we modified the synthesis of the dialkoxy PPV to yield a narrow polydispersity sample. When fabricated into a single layer PLED with an aluminum cathode, the EL efficiency was almost two orders of magnitude higher than that of the conventional higher polydispersity PPV. A clear understanding of the photophysics involved in excited state migration in the previous experiments was deemed necessary. We observe that the photophysics of conjugated polymers used in PLEDs can be modeled as the sum of contributions from two species, isolated chain segments and aggregated chain segments in a mixed solvent system. This system also provides an important vehicle for probing the interaction between long and short conjugated segments in the blends of PPV and pentamer. The absorption and emission spectra of the solution mixtures under different concentration of good solvent (dioxane) and bad solvent (water) mimic a film like condition and subsequent quenching in luminescence efficiency and energy

  6. Plasmon-enhanced luminescence in novel complex conjugated polymer nanoparticles.

    PubMed

    Lang, Jiawei; Lu, Pengqi; Bi, Gang; Cai, Chunfeng; Wu, Huizhen

    2017-10-01

    A core-shell structure of novel complex conjugated polymer nanoparticles (CPNs) consisting of poly(2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylenevinylene), polyethyleneimine (PEI) is developed. PEI is used to construct CPN@PEI core-shell structure through electrostatic attraction, and shell thickness can be controlled by PEI. Small Au-Ag alloy nanoparticles (ANPs) are then inserted into CPN@PEI core-shell structure to plasmonically tune luminescence properties. The coupling structure with double polymer core-shell CPN@PEI and ANPs presents unique luminescent characters, and maximum luminescence enhancement is realized when shell thickness is 8.6 nm. The strategies taking polymer as shell material in construction of core-shell complex CPNs and tuning optical properties by ANPs shall have significant values in applications of CPNs as probes and fluorescent tags in biological science.

  7. RIR-MAPLE deposition of conjugated polymers and hybrid nanocomposites for application to optoelectronic devices

    SciTech Connect

    Stiff-Roberts, Adrienne D.; Pate, Ryan; McCormick, Ryan; Lantz, Kevin R.

    2012-07-30

    Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a variation of pulsed laser deposition that is useful for organic-based thin films because it reduces material degradation by selective absorption of infrared radiation in the host matrix. A unique emulsion-based RIR-MAPLE approach has been developed that reduces substrate exposure to solvents and provides controlled and repeatable organic thin film deposition. In order to establish emulsion-based RIR-MAPLE as a preferred deposition technique for conjugated polymer or hybrid nanocomposite optoelectronic devices, studies have been conducted to demonstrate the value added by the approach in comparison to traditional solution-based deposition techniques, and this work will be reviewed. The control of hybrid nanocomposite thin film deposition, and the photoconductivity in such materials deposited using emulsion-based RIR-MAPLE, will also be reviewed. The overall result of these studies is the demonstration of emulsion-based RIR-MAPLE as a viable option for the fabrication of conjugated polymer and hybrid nanocomposite optoelectronic devices that could yield improved device performance.

  8. Very Small Bandgap π-Conjugated Polymers with Extended Thienoquinoids.

    PubMed

    Kawabata, Kohsuke; Saito, Masahiko; Osaka, Itaru; Takimiya, Kazuo

    2016-06-22

    The introduction of quinoidal character to π-conjugated polymers is one of the effective approaches to reducing the bandgap. Here we synthesized new π-conjugated polymers (PBTD4T and PBDTD4T) incorporating thienoquinoids 2,2'-bithiophene-5,5'-dione (BTD) and benzo[1,2-b:4,5-b']dithiophene-2,6-dione (BDTD) as strong electron-deficient (acceptor) units. PBTD4T showed a deep LUMO energy level of -3.77 eV and a small bandgap of 1.28 eV, which are similar to those of the analog using thieno[3,2-b]thiophene-2,5-dione (TTD) (PTTD4T). PBDTD4T had a much deeper LUMO energy level of -4.04 eV and a significantly smaller bandgap of 0.88 eV compared to those of the other two polymers. Interestingly, PBDTD4T showed high transparency in the visible region. The very small bandgap of PBDTD4T can be rationalized by the enhanced contribution of the resonance backbone structure in which the p-benzoquinodimethane skeleton in the BDTD unit plays a crucial role. PBTD4T and PBDTD4T exhibited ambipolar charge transport with more balanced mobilities between the hole and the electron than PTTD4T. We believe that the very small bandgap, i.e., the high near-infrared activity, as well as the well-balanced ambipolar property of the π-conjugated polymers based on these units would be of particular interest in the fabrication of next-generation organic devices.

  9. Conjugation of bioactive groups to poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)] films.

    PubMed

    Prime, Emma L; Cooper-White, Justin J; Qiao, Greg G

    2007-12-06

    A novel PLA-based polymer containing reactive pendent ketone or hydroxyl groups was synthesized by the copolymerization of L-lactide with epsilon-caprolactone-based monomers. The polymer was activated with NPC, resulting in an amine-reactive polymer which was then cast into thin polymeric films, either alone or as part of a blend with PLGA, before immersion into a solution of the cell adhesion peptide GRGDS in PBS buffer allowed for conjugation of GRGDS to the film surfaces. Subsequent 3T3 fibroblast cell adhesion studies demonstrated an increase in cellular adhesion and spreading over films cast from unmodified PLGA. Hence the new polymer can be used to obtain covalent linkage of amine-containing molecules to polymer surfaces.

  10. Protein-Polymer Conjugates: Synthetic Approaches by Controlled Radical Polymerizations & Interesting Applications

    PubMed Central

    Grover, Gregory N.; Maynard, Heather D.

    2011-01-01

    Protein-polymer conjugates are of interest to researchers in diverse fields. Attachment of polymers to proteins results in improved pharmacokinetics, which is important in medicine. From an engineering standpoint, conjugates are exciting because they exhibit properties of both the biomolecules and synthetic polymers. This allows the activity of the protein to be altered or tuned, a key aspect in therapeutic design, anchoring conjugates to surfaces, and utilizing these materials for supramolecular self-assembly. Thus, there is broad interest in straightforward synthetic methods to make protein-polymer conjugates. Controlled radical polymerization (CRP) techniques have emerged as excellent strategies to make conjugates because the resulting polymers have narrow molecular weight distributions, targeted molecular weights, and attach to specific sites on proteins. Herein, recent advances in the synthesis and application of protein-polymer conjugates by CRP are highlighted. PMID:21071260

  11. Light-emitting conjugated polymers with microporous network architecture: interweaving scaffold promotes electronic conjugation, facilitates exciton migration, and improves luminescence.

    PubMed

    Xu, Yanhong; Chen, Long; Guo, Zhaoqi; Nagai, Atsushi; Jiang, Donglin

    2011-11-09

    Herein we report a strategy for the design of highly luminescent conjugated polymers by restricting rotation of the polymer building blocks through a microporous network architecture. We demonstrate this concept using tetraphenylethene (TPE) as a building block to construct a light-emitting conjugated microporous polymer. The interlocked network successfully restricted the rotation of the phenyl units, which are the major cause of fluorescence deactivation in TPE, thus providing intrinsic luminescence activity for the polymers. We show positive "CMP effects" that the network promotes π-conjugation, facilitates exciton migration, and improves luminescence activity. Although the monomer and linear polymer analogue in solvents are nonemissive, the network polymers are highly luminescent in various solvents and the solid state. Because emission losses due to rotation are ubiquitous among small chromophores, this strategy can be generalized for the de novo design of light-emitting materials by integrating the chromophores into an interlocked network architecture.

  12. Aqueous Processing for Printed Organic Electronics: Conjugated Polymers with Multistage Cleavable Side Chains.

    PubMed

    Schmatz, Brian; Yuan, Zhibo; Lang, Augustus W; Hernandez, Jeff L; Reichmanis, Elsa; Reynolds, John R

    2017-09-27

    The ability to process conjugated polymers via aqueous solution is highly advantageous for reducing the costs and environmental hazards of large scale roll-to-roll processing of organic electronics. However, maintaining competitive electronic properties while achieving aqueous solubility is difficult for several reasons: (1) Materials with polar functional groups that provide aqueous solubility can be difficult to purify and characterize, (2) many traditional coupling and polymerization reactions cannot be performed in aqueous solution, and (3) ionic groups, though useful for obtaining aqueous solubility, can lead to a loss of solid-state order, as well as a screening of any applied bias. As an alternative, we report a multistage cleavable side chain method that combines desirable aqueous processing attributes without sacrificing semiconducting capabilities. Through the attachment of cleavable side chains, conjugated polymers have for the first time been synthesized, characterized, and purified in organic solvents, converted to a water-soluble form for aqueous processing, and brought through a final treatment to cleave the polymer side chains and leave behind the desired electronic material as a solvent-resistant film. Specifically, we demonstrate an organic soluble polythiophene that is converted to an aqueous soluble polyelectrolyte via hydrolysis. After blade coating from an aqueous solution, UV irradiation is used to cleave the polymer's side chains, resulting in a solvent-resistant, electroactive polymer thin film. In application, this process results in aqueous printed materials with utility for solid-state charge transport in organic field effect transistors (OFETs), along with red to colorless electrochromism in ionic media for color changing displays, demonstrating its potential as a universal method for aqueous printing in organic electronics.

  13. Novel Effects of Compressed CO2 Molecules on Structural Ordering and Charge Transport in Conjugated Poly(3-hexylthiophene) Thin Films

    DOE PAGES

    Jiang, Naisheng; Sendogdular, Levent; Sen, Mani; ...

    2016-10-06

    We report the effects of compressed CO2 molecules as a novel plasticization agent for poly(3- hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence Xray diffraction measurements after drying the films via rapid depressurization to atmosphericmore » pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO2regardless of the type of polymers, the present findings suggest that the CO2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.tion films.« less

  14. Naphthalene Diimide Based n-Type Conjugated Polymers as Efficient Cathode Interfacial Materials for Polymer and Perovskite Solar Cells.

    PubMed

    Jia, Tao; Sun, Chen; Xu, Rongguo; Chen, Zhiming; Yin, Qingwu; Jin, Yaocheng; Yip, Hin-Lap; Huang, Fei; Cao, Yong

    2017-10-05

    A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure-performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.

  15. Polythiophenes Comprising Conjugated Pendants for Polymer Solar Cells: A Review

    PubMed Central

    Wang, Hsing-Ju; Chen, Chih-Ping; Jeng, Ru-Jong

    2014-01-01

    Polythiophene (PT) is one of the widely used donor materials for solution-processable polymer solar cells (PSCs). Much progress in PT-based PSCs can be attributed to the design of novel PTs exhibiting intense and broad visible absorption with high charge carrier mobility to increase short-circuit current density (Jsc), along with low-lying highest occupied molecular orbital (HOMO) levels to achieve large open circuit voltage (Voc) values. A promising strategy to tailor the photophysical properties and energy levels via covalently attaching electron donor and acceptor pendants on PTs backbone has attracted much attention recently. The geometry, electron-donating capacity, and composition of conjugated pendants are supposed to be the crucial factors in adjusting the conformation, energy levels, and photovoltaic performance of PTs. This review will go over the most recent approaches that enable researchers to obtain in-depth information in the development of PTs comprising conjugated pendants for PSCs. PMID:28788575

  16. Role of redox centre in charge transport investigated by novel self-assembled conjugated polymer molecular junctions

    PubMed Central

    Wang, Zongrui; Dong, Huanli; Li, Tao; Hviid, Rune; Zou, Ye; Wei, Zhongming; Fu, Xiaolong; Wang, Erjing; Zhen, Yonggang; Nørgaard, Kasper; Laursen, Bo W.; Hu, Wenping

    2015-01-01

    Molecular electronics describes a field that seeks to implement electronic components made of molecular building blocks. To date, few studies have used conjugated polymers in molecular junctions despite the fact that they potentially transport charge more efficiently than the extensively investigated small-molecular systems. Here we report a novel type of molecular tunnelling junction exploring the use of conjugated polymers, which are self-assembled into ultrathin films in a distinguishable ‘planar' manner from the traditional vertically oriented small-molecule monolayers. Electrical measurements on the junctions reveal molecular-specific characteristics of the polymeric molecules in comparison with less conjugated small molecules. More significantly, we decorate redox-active functionality into polymeric backbones, demonstrating a key role of redox centre in the modulation of charge transport behaviour via energy level engineering and external stimuli, and implying the potential of employing tailor-made polymeric components as alternatives to small molecules for future molecular-scale electronics. PMID:26085081

  17. Thiolated polymers: synthesis and in vitro evaluation of polymer-cysteamine conjugates.

    PubMed

    Bernkop-Schnürch, A; Clausen, A E; Hnatyszyn, M

    2001-09-11

    The purpose of the present study was to synthesize and characterize novel thiolated polymers. Mediated by a carbodiimide cysteamine was covalently linked to sodium carboxymethylcellulose (CMC) and polycarbophil (PCP). The resulting CMC-cysteamine conjugates displayed 77.9+/-6.7 and 365.1+/-8.7 micromol thiol groups per gram of polymer, whereas the PCP-cysteamine conjugates showed 26.3+/-1.9 and 122.7+/-3.8 micromol thiol groups per gram of polymer (mean+/-S.D.; n=3). In aqueous solutions above pH 5.0 both modified polymers were capable of forming inter- and/or intra-molecular disulfide bonds. The reaction velocity of this oxidation process was accelerated with a decrease in the proton concentration. The oxidation proceeded more rapidly within thiolated CMC than within thiolated PCP. Permeation studies carried out in Ussing-type chambers with freshly excised intestinal mucosa from guinea pigs utilizing sodium fluorescein as model drug for the paracellular uptake revealed an enhancement ratio (R=P(app) (conjugate)/P(app) (control)) of 1.15 and 1.41 (mean+/-S.D.; n=3) for the higher thiolated CMC-cysteamine (0.5%; m/v) and PCP-cysteamine conjugate (1.0%; m/v), respectively. The decrease in the transepithelial electrical resistance values was in good correlation with the enhancement ratios. Due to a high crosslinking tendency by the formation of disulfide bonds stabilizing drug carrier systems based on thiolated polymers and a permeation enhancing effect, CMC- and PCP-cysteamine conjugates represent promising excipients for the development of novel drug delivery systems.

  18. Preparation and characterization of gradient polymer films

    SciTech Connect

    Smith, S.C.

    1987-01-01

    Gradient polymers are multicomponent polymers whose chemical constitution varies with depth in the sample. Although these polymers may possess unique mechanical, optical, and barrier properties they remain relatively unexplored. This work is a study of the preparation of gradient polymers by sequential exposure of films to a diffusing monomer followed by electron beam irradiation. Initial experiments involved immersion of poly(vinyl chloride) (PVC) films in styrene or n-butyl methacrylate (BMA) for various time periods followed by irradiation with 1 or 10 megarads of accelerated electrons. A significant amount of poly(n-butyl methacrylate) (PBMA) formed in PVC/BMA systems, but little polystyrene could be found in the PVC/styrene films. A second set of experiments involved immersion of PVC and polyethylene (PE) films in BMA for 20, 40, 60, and 720 minutes followed by irradiation with 10 megarads of electrons. These films were then characterized using optical microscopy, quantitative transmission Fourier transform infrared spectroscopy (FTIR), and a depth profiling procedure based on quantitative attenuated total reflection (ATR) FTIR. It was concluded that the mechanism of PBMA formation in the polyethylene films was a result of events immediately following irradiation. Atmospheric oxygen diffusing into irradiated films trapped free radicals at the film surfaces. This was followed by storage in an evacuated desiccator where unintentional exposure to BMA vapor took place. This BMA reacted with free radicals that remained within the film cores, polymerizing to PBMA.

  19. Novel effects of compressed CO2 molecules on structural ordering and charge transport in conjugated poly(3-hexylthiophene) thin films.

    PubMed

    Jiang, Naisheng; Sendogdular, Levent; Sen, Mani; Endoh, Maya K; Koga, Tadanori; Fukuto, Masafumi; Akgun, Bulent; Satija, Sushil K; Nam, Chang-Yong

    2016-10-06

    We report the effects of compressed CO2 molecules as a novel plasticization agent for poly(3-hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence X-ray diffraction measurements after drying the films via rapid depressurization to atmospheric pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO2 regardless of the type of polymers, the present findings suggest that the CO2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.

  20. Keto-Functionalized Polymer Scaffolds As Versatile Precursors to Polymer Side Chain Conjugates.

    PubMed

    Liu, Jingquan; Li, Ronald C; Sand, Gregory J; Bulmus, Volga; Davis, Thomas P; Maynard, Heather D

    2013-01-01

    A new methacrylate monomer with a reactive ketone side-chain, 2-(4-oxo-pentanoate) ethyl methacrylate (PAEMA), was synthesized and subsequently polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization to give a polymer with a narrow molecular weight distribution (PDI = 1.25). The polymer was chain extended with poly(ethylene glycol methyl ether acrylate) (PEGMA) to yield a block copolymer. Aminooxy containing small molecules and oligoethylene glycol were conjugated to the ketone functionality of the side chain in high yields. Cytotoxicity of the oxime-linked tetra(ethylene glycol) polymer to mouse fibroblast cells was investigated; the polymer was found to be non-cytotoxic up to 1 mg/mL. The ease with which this polymer is functionalized, suggests that it may be useful in forming tailored polymeric medicines.

  1. Hydrochromic conjugated polymers for human sweat pore mapping

    NASA Astrophysics Data System (ADS)

    Lee, Joosub; Pyo, Minkyeong; Lee, Sang-Hwa; Kim, Jaeyong; Ra, Moonsoo; Kim, Whoi-Yul; Park, Bum Jun; Lee, Chan Woo; Kim, Jong-Man

    2014-04-01

    Hydrochromic materials have been actively investigated in the context of humidity sensing and measuring water contents in organic solvents. Here we report a sensor system that undergoes a brilliant blue-to-red colour transition as well as ‘Turn-On’ fluorescence upon exposure to water. Introduction of a hygroscopic element into a supramolecularly assembled polydiacetylene results in a hydrochromic conjugated polymer that is rapidly responsive (<20 μs), spin-coatable and inkjet-compatible. Importantly, the hydrochromic sensor is found to be suitable for mapping human sweat pores. The exceedingly small quantities (sub-nanolitre) of water secreted from sweat pores are sufficient to promote an instantaneous colorimetric transition of the polymer. As a result, the sensor can be used to construct a precise map of active sweat pores on fingertips. The sensor technology, developed in this study, has the potential of serving as new method for fingerprint analysis and for the clinical diagnosis of malfunctioning sweat pores.

  2. Silica passivated conjugated polymer nanoparticles for biological imaging applications

    NASA Astrophysics Data System (ADS)

    Bourke, Struan; Urbano, Laura; Olona, Antoni; Valderrama, Ferran; Dailey, Lea Ann; Green, Mark A.

    2017-02-01

    Colorectal and prostate cancers are major causes of cancer-related death, with early detection key to increased survival. However, as symptoms occur during advanced stages and current diagnostic methods have limitations, there is a need for new fluorescent probes that remain bright, are biocompatible and can be targeted. Conjugated polymer nanoparticles have shown great promise in biological imaging due to their unique optical properties. We have synthesised small, bright, photo-stable CN-PPV, nanoparticles encapsulated with poloxamer polymer and a thin silica shell. By incubating the CN-PPV silica shelled cross-linked (SSCL) nanoparticles in mammalian (HeLa) cells; we were able to show that cellular uptake occurred. Uptake was also shown by incubating the nanoparticles in RWPE-1, WPE1-NB26 and WPE1- NA22 prostate cancer cell lines. Finally, HEK cells were used to show the particles had limited cytotoxicity.

  3. Sustained gastrointestinal activity of dendronized polymer-enzyme conjugates

    NASA Astrophysics Data System (ADS)

    Fuhrmann, Gregor; Grotzky, Andrea; Lukić, Ružica; Matoori, Simon; Luciani, Paola; Yu, Hao; Zhang, Baozhong; Walde, Peter; Schlüter, A. Dieter; Gauthier, Marc A.; Leroux, Jean-Christophe

    2013-07-01

    Methods to stabilize and retain enzyme activity in the gastrointestinal tract are investigated rarely because of the difficulty of protecting proteins from an environment that has evolved to promote their digestion. Preventing the degradation of enzymes under these conditions, however, is critical for the development of new protein-based oral therapies. Here we show that covalent conjugation to polymers can stabilize orally administered therapeutic enzymes at different locations in the gastrointestinal tract. Architecturally and functionally diverse polymers are used to protect enzymes sterically from inactivation and to promote interactions with mucin on the stomach wall. Using this approach the in vivo activity of enzymes can be sustained for several hours in the stomach and/or in the small intestine. These findings provide new insight and a firm basis for the development of new therapeutic and imaging strategies based on orally administered proteins using a simple and accessible technology.

  4. Highly Ordered Single Conjugated Polymer Chain Rod Morphologies

    SciTech Connect

    Adachi, Takuji; Brazard, Johanna; Chokshi, Paresh; Ganesan, Venkat; Bolinger, Joshua; Barbara, Paul F.

    2010-10-15

    We have reexamined the fluorescence polarization anisotropy of single polymer chains of the prototypical conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) isolated in a poly(methyl methacrylate) (PMMA) matrix employing improved synthetic samples that contain a much smaller number of tetrahedral chemical defects per chain. The new measurements reveal a much larger fraction of highly anisotropic MEH-PPV chains, with >70% of the chains exhibiting polarization anisotropy values falling in the range of 0.6-0.9. High anisotropy is strong evidence for a rod-shaped conformation. A comparison of the experimental results with coarse grain, beads on a chain simulations reveals that simulations with the usual bead-bead pairwise additive potentials cannot reproduce the observed large fraction of high polarization values. Apparently, this type of potential lacks some yet to be identified molecular feature that is necessary to accurately simulate the experimental results.

  5. Smart hybrid materials by conjugation of responsive polymers to biomacromolecules.

    PubMed

    Cobo, Isidro; Li, Ming; Sumerlin, Brent S; Perrier, Sébastien

    2015-02-01

    The chemical structure and function of biomacromolecules has evolved to fill many essential roles in biological systems. More specifically, proteins, peptides, nucleic acids and polysaccharides serve as vital structural components, and mediate chemical transformations and energy/information storage processes required to sustain life. In many cases, the properties and applications of biological macromolecules can be further expanded by attaching synthetic macromolecules. The modification of biomacromolecules by attaching a polymer that changes its properties in response to environmental variations, thus affecting the properties of the biomacromolecule, has led to the emergence of a new family of polymeric biomaterials. Here, we summarize techniques for conjugating responsive polymers to biomacromolecules and highlight applications of these bioconjugates reported so far. In doing so, we aim to show how advances in synthetic tools could lead to rapid expansion in the variety and uses of responsive bioconjugates.

  6. Hydrochromic conjugated polymers for human sweat pore mapping.

    PubMed

    Lee, Joosub; Pyo, Minkyeong; Lee, Sang-hwa; Kim, Jaeyong; Ra, Moonsoo; Kim, Whoi-Yul; Park, Bum Jun; Lee, Chan Woo; Kim, Jong-Man

    2014-04-29

    Hydrochromic materials have been actively investigated in the context of humidity sensing and measuring water contents in organic solvents. Here we report a sensor system that undergoes a brilliant blue-to-red colour transition as well as 'Turn-On' fluorescence upon exposure to water. Introduction of a hygroscopic element into a supramolecularly assembled polydiacetylene results in a hydrochromic conjugated polymer that is rapidly responsive (<20 μs), spin-coatable and inkjet-compatible. Importantly, the hydrochromic sensor is found to be suitable for mapping human sweat pores. The exceedingly small quantities (sub-nanolitre) of water secreted from sweat pores are sufficient to promote an instantaneous colorimetric transition of the polymer. As a result, the sensor can be used to construct a precise map of active sweat pores on fingertips. The sensor technology, developed in this study, has the potential of serving as new method for fingerprint analysis and for the clinical diagnosis of malfunctioning sweat pores.

  7. Making Glasses Conduct: Electrochemical Doping of Redox-Active Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Boudouris, Bryan

    Optoelectronically-active macromolecules have been established as promising materials in myriad organic electronic applications (e.g., organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices). To date, however, the majority of the work surrounding these materials has focused on materials with a great deal of conjugation along their macromolecular backbones and with varying degrees of crystalline structure. Here, we describe an emerging class of macromolecular charge conductors, radical polymers, that: (1) do not contain conjugation and (2) are completely amorphous glasses. Radical polymers contain non-conjugated macromolecular backbones and stable radical sites along the side chains of the electronically-active materials. In contrast to conjugated polymer systems, these materials conduct charge in the solid state through oxidation-reduction (redox) reactions along these pendant groups. Specifically, we demonstrate that controlling the chemical functionality of the pendant groups and the molecular mobility of the macromolecular backbones significantly impacts the charge transport ability of the pristine (i.e., not doped) radical polymers species. Through proper control of these crucial parameters, we show that radical polymers can have electrical conductivity and charge mobility values on par with commonly-used conjugated polymers. Importantly, we also highlight the ability to dope radical polymers with redox-active small molecule species. This doping, in turn, increases the electrical conductivity of the glassy radical polymer thin films in a manner akin to what is observed in traditional conjugated polymer systems. In this way, we establish a means by which to fabricate optically-transparent and colorless thin film glasses capable of conducting charge in a rather rapid manner. We anticipate that these fundamental insights will prove crucial in developing new transparent conducting layers for future electronic applications.

  8. Conjugated Polymer Alignment: Synergisms Derived from Microfluidic Shear Design and UV Irradiation.

    PubMed

    Wang, Gang; Chu, Ping-Hsun; Fu, Boyi; He, Zhongyuan; Kleinhenz, Nabil; Yuan, Zhibo; Mao, Yimin; Wang, Hongzhi; Reichmanis, Elsa

    2016-09-21

    Solution shearing has attracted great interest for the fabrication of robust and reliable, high performance organic electronic devices, owing to applicability of the method to large area and continuous fabrication, as well as its propensity to enhance semiconductor charge transport characteristics. To date, effects of the design of the blade shear features (especially the microfluidic shear design) and the prospect of synergistically combining the shear approach with an alternate process strategy have not been investigated. Here, a generic thin film fabrication concept that enhanced conjugated polymer intermolecular alignment and aggregation, improved orientation (both nanoscale and long-range), and narrowed the π-π stacking distance is demonstrated for the first time. The impact of the design of shearing blade microfluidic channels and synergistic effects of fluid shearing design with concomitant irradiation strategies were demonstrated, enabling fabrication of polymer-based devices with requisite morphologies for a range of applications.

  9. Diketopyrrolopyrrole-based Conjugated Polymers Bearing Branched Oligo(Ethylene Glycol) Side Chains for Photovoltaic Devices.

    PubMed

    Chen, Xingxing; Zhang, Zijian; Ding, Zicheng; Liu, Jun; Wang, Lixiang

    2016-08-22

    Conjugated polymers are essential for solution-processable organic opto-electronic devices. In contrast to the great efforts on developing new conjugated polymer backbones, research on developing side chains is rare. Herein, we report branched oligo(ethylene glycol) (OEG) as side chains of conjugated polymers. Compared with typical alkyl side chains, branched OEG side chains endowed the resulting conjugated polymers with a smaller π-π stacking distance, higher hole mobility, smaller optical band gap, higher dielectric constant, and larger surface energy. Moreover, the conjugated polymers with branched OEG side chains exhibited outstanding photovoltaic performance in polymer solar cells. A power conversion efficiency of 5.37 % with near-infrared photoresponse was demonstrated and the device performance could be insensitive to the active layer thickness.

  10. A highly sensitive immunosensor based on ITO thin films covered by a new semi-conductive conjugated polymer for the determination of TNFα in human saliva and serum samples.

    PubMed

    Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa Kemal

    2017-11-15

    A novel, ultrasensitive impedimetric immunosensor was constructed for the detection of tumor necrosis factor α (TNFα) by using Poly(3-thiophene acetic acid) (P3), a conjugated polymer as an immobilization matrix. The polymer P3 contains a lot of carboxylic acid groups on its surface that provide a larger biorecognition surface. This developed immunosensor was prepared on hydroxy-bearing ITO surface via an ester bond linkage of polymer P3 to immobilize anti-TNF α antibodies. The ITO electrode modification steps and interaction between anti-TNF α antibody and TNF α antigen were monitored by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS) method. After the analytical parameters optimization, a linear detection response from 0.01pg/mL to 2pg/mL, a limit of detection LOD of 3.7 fg/mL and a limit of quantification (LOQ) of 12.4 fg/mL were achieved, which provided accurate results (relative standard deviation; 4.03%). The characterization of this developed immunosensor was performed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (EDX) mapping and atomic force microscopy (AFM). The immunosensor allowed a simple and fast detection of TNF α antigen in human serum and satisfied recoveries (98.69-105.20%) were obtained by using standard addition method. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Efficient separation of conjugated polymers using a water soluble glycoprotein matrix: from fluorescence materials to light emitting devices.

    PubMed

    Hendler, Netta; Wildeman, Jurjen; Mentovich, Elad D; Schnitzler, Tobias; Belgorodsky, Bogdan; Prusty, Deepak K; Rimmerman, Dolev; Herrmann, Andreas; Richter, Shachar

    2014-03-01

    Optically active bio-composite blends of conjugated polymers or oligomers are fabricated by complexing them with bovine submaxilliary mucin (BSM) protein. The BSM matrix is exploited to host hydrophobic extended conjugated π-systems and to prevent undesirable aggregation and render such materials water soluble. This method allows tuning the emission color of solutions and films from the basic colors to the technologically challenging white emission. Furthermore, electrically driven light emitting biological devices are prepared and operated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Aqueous Processing for Printed Organic Electronics: Conjugated Polymers with Multistage Cleavable Side Chains

    PubMed Central

    2017-01-01

    The ability to process conjugated polymers via aqueous solution is highly advantageous for reducing the costs and environmental hazards of large scale roll-to-roll processing of organic electronics. However, maintaining competitive electronic properties while achieving aqueous solubility is difficult for several reasons: (1) Materials with polar functional groups that provide aqueous solubility can be difficult to purify and characterize, (2) many traditional coupling and polymerization reactions cannot be performed in aqueous solution, and (3) ionic groups, though useful for obtaining aqueous solubility, can lead to a loss of solid-state order, as well as a screening of any applied bias. As an alternative, we report a multistage cleavable side chain method that combines desirable aqueous processing attributes without sacrificing semiconducting capabilities. Through the attachment of cleavable side chains, conjugated polymers have for the first time been synthesized, characterized, and purified in organic solvents, converted to a water-soluble form for aqueous processing, and brought through a final treatment to cleave the polymer side chains and leave behind the desired electronic material as a solvent-resistant film. Specifically, we demonstrate an organic soluble polythiophene that is converted to an aqueous soluble polyelectrolyte via hydrolysis. After blade coating from an aqueous solution, UV irradiation is used to cleave the polymer’s side chains, resulting in a solvent-resistant, electroactive polymer thin film. In application, this process results in aqueous printed materials with utility for solid-state charge transport in organic field effect transistors (OFETs), along with red to colorless electrochromism in ionic media for color changing displays, demonstrating its potential as a universal method for aqueous printing in organic electronics. PMID:28979937

  13. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, Israel; Gottesfeld, Shimshon; Sabatani, Eyal

    1992-01-01

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventioonally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

  14. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

    1992-04-28

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol. 2 figs.

  15. Polymer Conjugation as a Strategy for Long-Range Order in Supramolecular Polymers.

    PubMed

    Benjamin, Ari; Keten, Sinan

    2016-04-07

    Supramolecular polymers are polymers in which the individual subunits self-assemble via noncovalent and reversible bonds. An important axis of control for systems of mixed subunit composition is the order in which the subunit types assemble. Existing ordering techniques, which rely on pairwise interactions through the inclusion of highly specific chemistry, have the downside that patterns of length n require n specific chemistries, making long-range order complicated to attain. Here we present a simple alternative method: we attach varying numbers of polymers to self-assembling subunits, in our case ring shaped macrocycles, and the polymers' aversion to confinement imposes system order. We evaluate the feasibility of the strategy using coarse-grained molecular dynamics simulations of polymer-conjugated rings designed to model cyclic peptide nanotubes. We discuss the effects of polymer conjugation on the energetics of association and predict the equilibrium orderings for various ratios of ring types. The emergent patterns are associated with a certain stochastic disorder, which we quantify by deriving and employing a formula for the expected statistical weight of any pattern within the ensemble of all possible orderings.

  16. Thiophene fused azacoronenes: regioselective synthesis, self organization, charge transport, and its incorporation in conjugated polymers

    DOEpatents

    Liu, Yi; He, Bo

    2015-09-15

    A regioselective synthesis of an azacoronene fused with two peripheral thiophene groups has been realized through a concise synthetic route. The resulting thienoazacoronene (TAC) derivatives show high degree of self-organization in solution, in single crystals, in the bulk, and in spuncast thin films. Spuncast thin film field-effect transistors of the TACs exhibited mobilities up to 0.028 cm.sup.2V.sup.-1 S.sup.-1, which is among the top field effect mobilities for solution processed discotic materials. Organic photovoltaic devices using TAC-containing conjugated polymers as the donor material exhibited a high open-circuit voltage of 0.89 V, which was ascribable to TAC's low-lying highest occupied molecular orbital energy level.

  17. Conjugated polymers mediate effective activation of the Mammalian Ion Channel Transient Receptor Potential Vanilloid 1.

    PubMed

    Lodola, F; Martino, N; Tullii, G; Lanzani, G; Antognazza, M R

    2017-08-16

    Selective and rapid regulation of ionic channels is pivotal to the understanding of physiological processes and has a crucial impact in developing novel therapeutic strategies. Transient Receptor Potential (TRP) channels are emerging as essential cellular switches that allow animals to respond to their environment. In particular, the Vanilloid Receptor 1 (TRPV1), besides being involved in the body temperature regulation and in the response to pain, has important roles in several neuronal functions, as cytoskeleton dynamics, injured neurons regeneration, synaptic plasticity. Currently available tools to modulate TRPV1 activity suffer from limited spatial selectivity, do not allow for temporally precise control, and are usually not reversible, thus limiting their application potential. The use of optical excitation would allow for overcoming all these limitations. Here, we propose a novel strategy, based on the use of light-sensitive, conjugated polymers. We demonstrate that illumination of a polymer thin film leads to reliable, robust and temporally precise control of TRPV1 channels. Interestingly, the activation of the channel is due to the combination of two different, locally confined effects, namely the release of thermal energy from the polymer surface and the variation of the local ionic concentration at the cell/polymer interface, both mediated by the polymer photoexcitation.

  18. Crystallization-driven assembly of conjugated-polymer-based nanostructures

    SciTech Connect

    Hayward, Ryan C.

    2016-10-15

    The goal of this project has been to improve our ability to simultaneously control the organization, and therefore the opto-electronic properties, of conjugated-polymer based materials across three different length-scales: 1) the molecular scale, in the sense of controlling growth and functionalization of highly crystalline semiconducting organic materials capable of efficient charge transport, 2) the nanoscale, in terms of positioning n- and p-type materials with domain sizes comparable to exciton diffusion lengths (~ 10 nm) to facilitate charge separation, and 3) the colloidal scale, such that well-defined crystalline nanoscale building blocks can be hierarchically organized into device layers. As described in more detail below, the project was successful in generating powerful new approaches to, and improved fundamental understanding of, processing and self-assembly of organic and hybrid semiconducting materials across all three length-scales. Although the goals of the project were formulated with primarily photovoltaic architectures in mind, the outcomes of the project have significant implications for a variety of conjugated-polymer-based devices including field-effect-transistors for sensors and logic devices, as well as potentially thermoelectrics and battery electrode materials. The project has resulted in 10 peer-reviewed publications to date [1-10], with several additional manuscripts currently in preparation.

  19. Structure and segmental dynamics in amorphous conjugated polymers

    NASA Astrophysics Data System (ADS)

    Zhan, Pengfei; Maranas, Janna; Gomez, Enrique

    2015-03-01

    Although it is well established that the microstructure strongly affects charge transport in organic semiconductors, the role of fluctuations of the structure on charge mobilities is still not well understood. We have examined the dynamics and structure in amorphous conjugated polymers poly(3-alkylthiophene)s (P3ATs) with neutron and x-ray scattering. We measured the segmental dynamics in amorphous P3ATs with quasi-elastic neutron scattering (QENS). The structure of amorphous P3ATs is measured with small-angle neutron scattering (SANS) and grazing incidence X-ray diffraction (GIXRD). Using SANS, we observe phase separation between the backbone and side-chains in all polymer samples for regiorandom P3ATs. Additionally, the analysis of the QENS data shows that longer side-chains relax faster compared with shorter side-chains and our further analysis of the elastic incoherent structure factor (EISF) suggests that the amplitude of proton motion on the thiophene rings increases by a factor of 3 as the side-chain length increases from 6 to 12, demonstrating that longer side chains lead to enhanced motion of conjugated rings. This work is done under the support of Dow Chemical Company

  20. Self-assembled conjugated polymer spheres as fluorescent microresonators

    PubMed Central

    Tabata, Kenichi; Braam, Daniel; Kushida, Soh; Tong, Liang; Kuwabara, Junpei; Kanbara, Takaki; Beckel, Andreas; Lorke, Axel; Yamamoto, Yohei

    2014-01-01

    Confinement of light inside an active medium cavity can amplify emission. Whispering gallery mode (WGM) is one of mechanisms that amplifies light effectively by confining it inside high-refractive-index microstructures, where light propagates along the circumference of a sphere via total internal reflection. Here we show that isolated single microspheres of 2–10 μm diameter, formed from self-assembly of π-conjugated alternating copolymers, display WGM photoemission induced by laser pumping. The wavelengths of the emission peaks depend sensitively on the sphere size, position of the excitation spot and refractive index of each polymer. The Q-factor increases with increasing sphere diameter and displays a linear correlation with the reciprocal radius, indicating that the small curvature increases the efficacy of the total internal reflection. WGM photoemission from π-conjugated polymer microspheres is unprecedented and may be of high technological impact since the microspheres fulfill the role of fluorophores, high-refractive-index media and resonators simultaneously, in addition to their simple fabrication process. PMID:25082187

  1. Macroscopic Alignment of One-Dimensional Conjugated Polymer Nanocrystallites for High-Mobility Organic Field-Effect Transistors.

    PubMed

    Chang, Mincheol; Choi, Dalsu; Egap, Eilaf

    2016-06-01

    Controlling the morphology of polymer semiconductors remains a fundamental challenge that hinders their widespread applications in electronic and optoelectronic devices and commercial feasibility. Although conjugated polymer nanowires (NWs) are envisioned to afford high charge-carrier mobility, the alignment of preformed conjugated polymer NWs has not been reported. Here, we demonstrate an extremely simple and effective strategy to generate well-aligned arrays of one-dimensional (1D) polymer semiconductors that exhibit remarkable enhancement in charge transport using a solution shear-coating technique. We show that solution shear coating of poly(alkylthiophene) NWs induces extension or coplanarization of the polymer backbone and highly aligned network films, which results in enhanced intra- and intermolecular ordering and reduced grain boundaries. Consequently, highly aligned poly(3-hexylthiophene) NWs exhibited over 33-fold enhancement in the average carrier mobility, with the highest mobility of 0.32 cm(2) V(-1) s(-1) compared to pristine films. The presented platform is a promising strategy and general approach for achieving well-aligned 1D nanostructures of polymer semiconductors and could enable the next generation of high-performance flexible electronic devices for a wide range of applications.

  2. High Dielectric Constant Polymer Film Capacitors (PREPRINT)

    DTIC Science & Technology

    2010-02-01

    film, and the test of our first generation prototype capacitors . High-K Polymeric Dielectrics Commercial polypropylene (PP) capacitor film has a...1994). 2. Maurizio Rabuffi and Guido Picci, “Status Quo and Future Prospects for Metallized Polypropylene Energy Storage Capacitors ”, IEEE Trans...AFRL-RZ-WP-TP-2010-2126 HIGH DIELECTRIC CONSTANT POLYMER FILM CAPACITORS (PREPRINT) Shihai Zhang, Brian Zellers, Dean Anderson, Paul

  3. Polymer enzyme conjugates as chiral ligands for sharpless dihydroxylation of alkenes in organic solvents.

    PubMed

    Konieczny, Stefan; Leurs, Melanie; Tiller, Joerg C

    2015-01-02

    Conjugates of enzymes and poly(2-methyloxazoline) were used as organosoluble amphiphilic polymer nanocontainers for dissolving osmate, thereby converting the enzymes into organosoluble artificial metalloenzymes. These were shown to catalyze the dihydroxylation of different alkenes with high enantioselectivity. The highest selectivities, found for osmate complexed with laccase polymer-enzyme conjugates (PECs), even exceed those of classical Sharpless catalysts.

  4. Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

    PubMed

    Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

    2017-09-07

    Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

  5. Site-Specific Zwitterionic Polymer Conjugates of a Protein Have Long Plasma Circulation.

    PubMed

    Bhattacharjee, Somnath; Liu, Wenge; Wang, Wei-Han; Weitzhandler, Isaac; Li, Xinghai; Qi, Yizhi; Liu, Jinyao; Pang, Yan; Hunt, Donald F; Chilkoti, Ashutosh

    2015-11-01

    Many proteins suffer from suboptimal pharmacokinetics (PK) that limit their utility as drugs. The efficient synthesis of polymer conjugates of protein drugs with tunable PK to optimize their in vivo efficacy is hence critical. We report here the first study of the in vivo behavior of a site-specific conjugate of a zwitterionic polymer and a protein. To synthesize the conjugate, we first installed an initiator for atom-transfer radical polymerization (ATRP) at the N terminus of myoglobin (Mb-N-Br). Subsequently, in situ ATRP was carried out in aqueous buffer to grow an amine-functionalized polymer from Mb-N-Br. The cationic polymer was further derivatized to two zwitterionic polymers by treating the amine groups of the cationic polymer with iodoacetic acid to obtain poly(carboxybetaine methacrylate) with a one-carbon spacer (PCBMA; C1 ), and sequentially with 3-iodopropionic acid and iodoacetic acid to obtain PCBMA(mix) with a mixture of C1 and C2 spacers. The Mb-N-PCBMA polymer conjugates had a longer in vivo plasma half-life than a PEG-like comb polymer conjugate of similar molecular weights (MW). The structure of the zwitterion plays a role in controlling the in vivo behavior of the conjugate, as the PCBMA conjugate with a C1 spacer had significantly longer plasma circulation than the conjugate with a mixture of C1 and C2 spacers.

  6. Navigating conjugated polymer actuated neural probes in a brain phantom

    NASA Astrophysics Data System (ADS)

    Daneshvar, Eugene D.; Kipke, Daryl; Smela, Elisabeth

    2012-04-01

    Neural probe insertion methods have a direct impact on the longevity of the device in the brain. Initial tissue and vascular damage caused by the probe entering the brain triggers a chronic tissue response that is known to attenuate neural recordings and ultimately encapsulate the probes. Smaller devices have been found to evoke reduced inflammatory response. One way to record from undamaged neural networks may be to position the electrode sites away from the probe. To investigate this approach, we are developing probes with controllably movable electrode projections, which would move outside of the zone that is damaged by the insertion of the larger probe. The objective of this study was to test the capability of conjugated polymer bilayer actuators to actuate neural electrode projections from a probe shank into a transparent brain phantom. Parylene neural probe devices, having five electrode projections with actuating segments and with varying widths (50 - 250 μm) and lengths (200 - 1000 μm) were fabricated. The electroactive polymer polypyrrole (PPy) was used to bend or flatten the projections. The devices were inserted into the brain phantom using an electronic microdrive while simultaneously activating the actuators. Deflections were quantified based on video images. The electrode projections were successfully controlled to either remain flat or to actuate out-of-plane and into the brain phantom during insertion. The projection width had a significant effect on their ability to deflect within the phantom, with thinner probes deflecting but not the wider ones. Thus, small integrated conjugated polymer actuators may enable multiple neuro-experiments and applications not possible before.

  7. Optical absorption in the substituted phenylene-based conjugated polymers: Theory and experiment

    SciTech Connect

    Chandross, M.; Mazumdar, S.; Liess, M.; Lane, P.A.; Vardeny, Z.V.; Hamaguchi, M.; Yoshino, K.

    1997-01-01

    We investigate theoretically and experimentally the effects of (2,5) chemical substitution on the optical absorption in the phenylene-based conjugated polymers. Theoretically, substitution destroys both the charge-conjugation symmetry and spatial symmetry that characterize the unsubstituted materials. Within Coulomb-correlated theoretical models, the effect of broken charge-conjugation symmetry alone on the underlying electronic structure and on the absorption spectrum is rather weak. When both broken spatial symmetry and broken charge-conjugation symmetry are taken into account, a strong effect on the electronic structure of polyphenylene derivatives is found. In spite of the strong effect of the broken symmetries on the electronic structure, the effect on the optical-absorption spectrum is weak. This surprising result is a consequence of the subtle nature of the configuration interaction in the substituted polyphenylenes within Coulomb-correlated models. We demonstrate numerically an approximate sum rule that governs the strength of an absorption band at 3.7 eV in the absorption spectra of poly(para-phenylene vinylene) (PPV) derivatives. Although substitution can make a previously forbidden transition weakly allowed, the latter acquires strength from a {open_quotes}finite-size band{close_quotes} at about the same energy, and not from a higher-energy band at 4.7 eV, as has been previously claimed. It is further predicted that the 3.7-eV band is polarized predominantly along the polymer-chain axis. We have measured the polarization dependence of the optical absorption in an oriented-substituted PPV film. We found that the two lowest-energy absorption bands are polarized predominantly parallel to the chain axis, while the band at 4.7 eV is polarized predominantly perpendicular to the chain axis. These results are in excellent agreement with the theory. {copyright} {ital 1997} {ital The American Physical Society}

  8. Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

    PubMed Central

    Wéry, Jany; Duvail, Jean-Luc; Lefrant, Serge; Yaya, Abu; Ewels, Chris

    2015-01-01

    Summary The mechanisms that control the photophysics of composite films made of a semiconducting conjugated polymer (poly(paraphenylene vinylene), PPV) mixed with single-walled carbon nanotubes (SWNT) up to a concentration of 64 wt % are determined by using photoexcitation techniques and density functional theory. Charge separation is confirmed experimentally by rapid quenching of PPV photoluminescence and changes in photocurrent starting at relatively low concentrations of SWNT. Calculations predict strong electronic interaction between the polymer and the SWNT network when nanotubes are semiconducting. PMID:26171290

  9. Creating Ordered Antibody Arrays with Antibody-Polymer Conjugates

    NASA Astrophysics Data System (ADS)

    Dong, Xuehui; Obermeyer, Allie; Olsen, Bradley

    Antibodies are a category of functional proteins that play crucial roles in the immune system and have been widely applied in the area of cancer therapeutics, targeting delivery, signal detection, and sensors. Due to the extremely large size and lack of specific functional groups on the surface, it is challenging to functionalize antibodies and manipulate the ordered packing of antibodies in an array with high density and proper orientation, which is critical to achieve outstanding performance in materials. In this work, we demonstrate an efficient and facile approach for preparing antibody-polymer conjugates with two-step sequential ``click'' reaction to form antibody-polymer block copolymers. Highly ordered nanostructures are fabricated based on the principles of block copolymer self-assembly. The nanostructures are studied with both small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Lamellae with alternating antibody domain and polymer domain are observed with an overall domain size of ~50 nm. The nanostructure not only increases the packing density and promotes proper orientation of the antibody, but also provides possible channel to facilitate substrate transportation and improves the stability of the antibody.

  10. Parallel Synthesis of photoluminescent π-conjugated polymers by polymer reactions of an organotitanium polymer with a titanacyclopentadiene unit.

    PubMed

    Matsumura, Yoshimasa; Fukuda, Katsura; Inagi, Shinsuke; Tomita, Ikuyoshi

    2015-04-01

    A regioregular organometallic polymer with titanacyclopentadiene unit, obtained by the reaction of a 2,7-diethynylfluorene derivative and a low-valent titanium complex, is subjected to the reaction with three kinds of electrophiles (i.e., sulfur monochloride, hydrochloric acid, and dichlorophenylphosphine) to give π-conjugated polymers possessing both fluorene and building blocks originated from the transformation of the titanacycles in the main chain. For example, a phosphole-containing polymer whose number-average molecular weight is estimated as 5000 is obtained in 50% yield. The obtained thiophene, butadiene, and phosphole-containing polymers exhibit efficient photoluminescence (PL) with emission colors of blue, green, and yellow, respectively. For example, the phosphole-containing polymer exhibits yellow PL with an emission maximum (Emax ) of 533 nm and a quantum yield (Φ) of 0.37.

  11. Thiophene polymer semiconductors for organic thin-film transistors.

    PubMed

    Ong, Beng S; Wu, Yiliang; Li, Yuning; Liu, Ping; Pan, Hualong

    2008-01-01

    Printed organic thin-film transistors (OTFTs) have received great interests as potentially low-cost alternative to silicon technology for application in large-area, flexible, and ultra-low-cost electronics. One of the critical materials for TFTs is semiconductor, which has a dominant impact on the transistor properties. We review here the structural studies and design of thiophene-based polymer semiconductors with respect to solution processability, ambient stability, molecular self-organization, and field-effect transistor properties for OTFT applications. We show that through judicial monomer design, delicately controlled pi-conjugation, and strategically positioned pendant side-chain distribution, novel solution-processable thiophene polymer semiconductors with excellent self-organization ability to form extended lamellar pi-stacking orders can be developed. OTFTs using semiconductors of this nature processed in ambient conditions have provided excellent field-effect transistor properties.

  12. A novel rapamycin-polymer conjugate based on a new poly(ethylene glycol) multiblock copolymer

    PubMed Central

    Tai, Wanyi; Chen, Zhijin; Barve, Ashutosh; Peng, Zhonghua; Cheng, Kun

    2014-01-01

    Purpose Rapamycin has demonstrated potent anti-tumor activity in preclinical and clinical studies. However, the clinical development of its formulations was hampered due to its poor solubility and undesirable distribution in vivo. Chemical modification of rapamycin presents an opportunity for overcoming the obstacles and improving its therapeutic index. The objective of this study is to develop a drug-polymer conjugate to increase the solubility and cellular uptake of rapamycin. Methods We developed the rapamycin-polymer conjugate using a novel, linear, poly(ethylene glycol) (PEG) based multiblock copolymer. Cytotoxicity and cellular uptake of the rapamycin-polymer conjugate were evaluated in various cancer cells. Results The rapamycin-polymer conjugate provides enhanced solubility in water compared with free rapamycin and shows profound activity against a panel of human cancer cell lines. The rapamycin-polymer conjugate also presents high drug loading capacity (wt% ~ 26%) when GlyGlyGly is used as a linker. Cellular uptake of the conjugate was confirmed by confocal microscopy examination of PC-3 cells that were cultured in the presence of FITC-labled polymer (FITC-polymer). Conclusion This study suggests that the rapamycin-polymer conjugate is a novel anti-cancer agent that may provide an attractive strategy for treatment of a wide variety of tumors. PMID:24072263

  13. Design of hybrid conjugated polymer materials: 1) Novel inorganic/organic hybrid semiconductors and 2) Surface modification via grafting approaches

    NASA Astrophysics Data System (ADS)

    Peterson, Joseph J.

    synthesized and characterized, and the material is found to be a high MW, soluble blue emitter which shows a higher glass transition temperature and greater stability than a non-hybrid polymer. UV absorbance and fluorescence spectroscopy indicated some electronic interaction between the conjugated polymer and the cages, but they did not appear to be fully conjugated in the traditional sense. Chapter 4 describes the design, synthesis, and characterization of poly(fluorene) with o-carborane in the backbone. Profound changes in the behavior of the polymer, from its polymerization behavior to its emission characteristics, were observed and their origins are discussed. Experiments to explore the nature of the cage/polymer interactions were performed and possible applications which take advantage of the unique nature of the o-carborane hybrid polymer are explored and discussed. Hybrid conjugated polymer materials via grafting approaches to surfaces and surface modification are discussed starting in chapter 5. The synthesis of a dibromofluorene-based silane coupling agent for the surface functionalization of oxide surfaces is presented, and the surface directed Ni(0) dehalogenative polymerization of poly(dihexylfluorene) is explored. Chapter 6 focuses on the exploration of conjugated polymer/cellulose hybrid materials. Surface medication of cellulose materials with monomer-like anchor points is discussed. Grafting of the modified cellulose with conjugated polymers was explored and the grafting of three different repeat structures based on fluorene-, fluorenevinylene-, and fluoreneethynylene motifs were optimized to provide a general route to cellulose/conjugated polymer hybrid materials. Characterization and possible applications of such hybrid materials are discussed. Finally, chapter 7 is devoted to the simultaneous surface patterning and functionalization of poly(2-hydroxyethylmethacrylate) thin films using a silane infusion-based wrinkling technique. While not a conjugated

  14. Perspective: Optical spectroscopy in π-conjugated polymers and how it can be used to determine multiscale polymer structures.

    PubMed

    Barford, William; Marcus, Max

    2017-04-07

    Exciton delocalization in conjugated polymer systems is determined by polymer conformations and packing. Since exciton delocalization determines the photoluminescent vibronic progression, optical spectroscopy provides an indirect link to polymer multiscale structures. This perspective describes our current theoretical understanding of how exciton delocalization in π-conjugated polymers determines their optical spectroscopy and further shows how exciton delocalization is related to conformational and environmental disorder. If the multiscale structures in conjugated polymer systems are known, then using first-principles modeling of excitonic processes it is possible to predict a wide-range of spectroscopic observables. We propose a reverse-engineering protocol of using these experimental observables in combination with theoretical and computational modeling to determine the multiscale polymers structures, thus establishing quantitative structure-function predictions.

  15. Mesoscale morphologies in polymer thin films.

    SciTech Connect

    Ramanathan, M.; Darling, S. B.

    2011-06-01

    In the midst of an exciting era of polymer nanoscience, where the development of materials and understanding of properties at the nanoscale remain a major R&D endeavor, there are several exciting phenomena that have been reported at the mesoscale (approximately an order of magnitude larger than the nanoscale). In this review article, we focus on mesoscale morphologies in polymer thin films from the viewpoint of origination of structure formation, structure development and the interaction forces that govern these morphologies. Mesoscale morphologies, including dendrites, holes, spherulites, fractals and honeycomb structures have been observed in thin films of homopolymer, copolymer, blends and composites. Following a largely phenomenological level of description, we review the kinetic and thermodynamic aspects of mesostructure formation outlining some of the key mechanisms at play. We also discuss various strategies to direct, limit, or inhibit the appearance of mesostructures in polymer thin films as well as an outlook toward potential areas of growth in this field of research.

  16. Pulse radiolysis studies on charge carriers in conjugated polymers

    NASA Astrophysics Data System (ADS)

    Burrows, H. D.; Miguel, M. da G.; Monkman, A. P.; Horsburgh, L. E.; Hamblett, I.; Navaratnam, S.

    2000-02-01

    The charged states of the conjugated polymers poly(2-methoxy,5-(2'-ethylhexyloxy)-p- phenylenevinylene) (MEH-PPV) and poly(2,5-pyridinediyl) (PPY) have been studied by pulse radiolysis. Following pulse radiolysis of argon-saturated solutions of MEH-PPV in chloroform, a new absorption is seen to grow in over a few hundred microseconds. This has a principal absorption at 1.43 eV and a weaker, low energy band (⩽0.80 eV), and is assigned to the positive one-electron charge state (positive polaron) of MEH-PPV. The slow absorption decay is unaffected by oxygen. Negative charge states (negative polarons), with absorptions around 1.4 eV, are produced upon pulse radiolysis of MEH-PPV in argon-saturated solutions in tetrahydrofuran (THF) or benzonitrile. A small solvatochromic shift is observed. In contrast to the behavior of the positive polaron, the MEH-PPV negative charge carriers decay fairly rapidly, and are readily quenched by molecular oxygen. Previous results on chemically produced positive and negative charge states of conjugated polymers and oligomers are discussed on the basis of these assignments, and comparison is made with theoretical calculations. Using benzophenone as a charge scavenger, pulse radiolysis of formic acid is shown to generate one-electron reducing species. Various derivatives of PPY, including a regioregular polymer (rPPY) and a hexyl substituted compound (HPPY) have been studied by pulse radiolysis in formic acid solution. With rPPY, new absorptions are observed at 2.59 and 1.40 eV, and are assigned to the one-electron reduced species. These are strongly quenched by molecular oxygen. With HPPY, the lower energy transition is broadened to give a maximum below 1.21 eV and a shoulder at 1.65 eV. The differences between rPPY and HPPY are interpreted on the basis of differences in the rigidity of the polymer. The relevance of these assignments to the identification of charged species in photoinduced absorption measurements is indicated.

  17. Theory of exciton transfer and diffusion in conjugated polymers

    SciTech Connect

    Barford, William; Tozer, Oliver Robert

    2014-10-28

    We describe a theory of Förster-type exciton transfer between conjugated polymers. The theory is built on three assumptions. First, we assume that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, and described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω < J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. The resulting expression for the exciton transfer rate has a familiar form, being a function of the exciton transfer integral and the effective Franck-Condon factors. The effective Franck-Condon factors are functions of the effective Huang-Rhys parameters, which are inversely proportional to the chromophore size. The Born-Oppenheimer expressions were checked against DMRG calculations, and are found to be within 10% of the exact value for a tiny fraction of the computational cost. This theory of exciton transfer is then applied to model exciton migration in conformationally disordered poly(p-phenylene vinylene). Key to this modeling is the assumption that the donor and acceptor chromophores are defined by local exciton ground states (LEGSs). Since LEGSs are readily determined by the exciton center-of-mass wavefunction, this theory provides a quantitative link between polymer conformation and exciton migration. Our Monte Carlo simulations indicate that the exciton diffusion length depends weakly on the conformation of the polymer, with the diffusion length increasing slightly as the chromophores became straighter and longer. This is largely a geometrical effect: longer and straighter chromophores extend over larger distances. The calculated diffusion lengths of ∼10 nm are in good agreement with experiment. The spectral

  18. Hydrophobic conjugated microporous polymers for sorption of human serum albumin

    NASA Astrophysics Data System (ADS)

    Zheng, Chunli; Du, Miaomiao; Feng, Shanshan; Sun, Hanxue; Li, An; He, Chi; Zhang, TianCheng; Wang, Qiaorui; Wei, Wei

    2016-02-01

    This paper investigated the sorption of human serum albumin (HSA) from water by three kinds of conjugated microporous polymers (CMPs) with surface hydrophobicity and intrinsic porosity. It was found that the three CMPs captured HSA with fast sorption kinetics and good working capacity. Equilibrium was obtained at 80 min for all the tests, and the maximum sorption quantity (qm) ranged from 0.07 to 0.14 mg/mg. With the increase in the particle external surface area of the CMPs, a greater extent of HSA sorption was achieved. Moreover, promoting the dispersion of CMPs in HSA aqueous solution was also beneficial to the extraction. Attenuated Total Reflection Fourier Transform Infrared spectroscopy verified the interactions between the CMPs and the Nsbnd H, Cdbnd O, and Csbnd N groups of HSA. This paper might provide fundamental guidance for the practical application of CMPs to proteins separation and recovery.

  19. Multicolor Conjugated Polymer Dots for Biological Fluorescence Imaging

    PubMed Central

    Wu, Changfeng; Bull, Barbara; Szymanski, Craig; Christensen, Kenneth; McNeill, Jason

    2009-01-01

    Highly fluorescent conjugated polymer dots were developed for demanding applications such as fluorescence imaging in live cells. These nanoparticles exhibit small particle diameters, extraordinary fluorescence brightness, and excellent photostability. Single particle fluorescence imaging and kinetic studies indicate much higher emission rates (∼108 s-1) and little or no blinking of the nanoparticles as compared to typical results for single dye molecules and quantum dots. Analysis of single particle photobleaching trajectories reveals excellent photostability — as many as 109 or more photons emitted per nanoparticle prior to irreversible photobleaching. The superior figures of merit of these new fluorescent probes, together with the demonstration of cellular imaging, indicate their enormous potential for demanding fluorescence-based imaging and sensing applications such as high speed super-resolution single molecule/particle tracking and highly sensitive assays. PMID:19206410

  20. Tuning hyperfine fields in conjugated polymers for coherent organic spintronics.

    PubMed

    Lee, Sang-Yun; Paik, Seo-Young; McCamey, Dane R; Yu, Justin; Burn, Paul L; Lupton, John M; Boehme, Christoph

    2011-02-23

    An appealing avenue for organic spintronics lies in direct coherent control of the spin population by means of pulsed electron spin resonance techniques. Whereas previous work has focused on the electrical detection of coherent spin dynamics, we demonstrate here the equivalence of an all-optical approach, allowing us to explore the influence of materials chemistry on the spin dynamics. We show that deuteration of the conjugated polymer side groups weakens the local hyperfine fields experienced by electron-hole pairs, thereby lowering the threshold for the resonant radiation intensity at which coherent coupling and spin beating occur. The technique is exquisitively sensitive to previously obscured material properties and offers a route to quantifying and tuning hyperfine fields in organic semiconductors.

  1. Conjugated Polymer Nanoparticles to Augment Photosynthesis of Chloroplasts.

    PubMed

    Wang, Yunxia; Li, Shengliang; Liu, Libing; Lv, Fengting; Wang, Shu

    2017-05-02

    By coating chloroplasts with conjugated polymer nanoparticles (CPNs), a new bio-optical hybrid photosynthesis system (chloroplast/CPNs) is developed. Since CPNs possess unique light harvesting ability, including the ultraviolet part that chloroplasts absorb less, chloroplast/CPN complexes can capture broader range of light to accelerate the electron transport rates in photosystem II (PS II), the critical protein complex in chloroplasts, and augment photosynthesis beyond natural chloroplasts. The degree of spectral overlay between emission of CPNs and absorption of chloroplasts is critical for the enhanced photosynthesis. This work exhibits good potential to explore new and facile nanoengineering strategy for reforming chloroplast with light-harvesting nanomaterials to enhance solar energy conversion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Tracking the coherent generation of polaron pairs in conjugated polymers

    NASA Astrophysics Data System (ADS)

    de Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F.; Plenio, Martin B.; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

    2016-12-01

    The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials.

  3. Exploiting EPR in polymer drug conjugate delivery for tumor targeting.

    PubMed

    Modi, Sweta; Prakash Jain, Jay; Domb, A J; Kumar, Neeraj

    2006-01-01

    Treatment of tumor tissue without affecting normal cells has always been formidable task for drug delivery scientists and this task is effectively executed by polymer drug conjugate (PDC) delivery. The novelty of this concept lies in the utilization of a physical mechanism called enhanced permeability and retention (EPR) for targeting tumors. EPR is a physiological phenomenon that is customary for fast growing tumor and solves the problem of targeting the miscreant tissue. PDCs offer added advantages of reduced deleterious effects of anticancer drugs and augmentation of its formulation capability (e.g. Solubility). There are now at least eleven PDCs that have entered phase I/II/III clinical trial as anticancer drugs. PDCs once entered into the tumor tissue, taking advantage of EPR, are endocytosed into the cell either by simple or receptor mediated endocytosis. Various polymeric carriers have been used with hydrolyzable linker arm for conjugation with bioactive moiety. The hydrolyzable linkages of PDC are broken down by acid hydrolyses of lysosomes and releases the drug. High concentrations of the chemotherapeutic agent are maintained near the nucleus, the target site. Passive targeting by PDCs is due to the physiological event of EPR, which is becoming one of the major thrust areas for targeting solid tumors.

  4. Hydrophilic Conjugated Polymers with Large Bandgaps and Deep-Lying HOMO Levels as an Efficient Cathode Interlayer in Inverted Polymer Solar Cells.

    PubMed

    Kan, Yuanyuan; Zhu, Yongxiang; Liu, Zhulin; Zhang, Lianjie; Chen, Junwu; Cao, Yong

    2015-08-01

    Two hydrophilic conjugated polymers, PmP-NOH and PmP36F-NOH, with polar diethanol-amine on the side chains and main chain structures of poly(meta-phenylene) and poly(meta-phenylene-alt-3,6-fluorene), respectively, are successfully synthesized. The films of PmP-NOH and PmP36F-NOH show absorption edges at 340 and 343 nm, respectively. The calculated optical bandgaps of the two polymers are 3.65 and 3.62 eV, respectively, the largest ones so far reported for hydrophilic conjugated polymers. PmP-NOH and PmP36F-NOH also possess deep-lying highest occupied molecular orbital levels of -6.19 and -6.15 eV, respectively. Inserting PmP-NOH and PmP36F-NOH as a cathode interlayer in inverted polymer solar cells with a PTB7/PC71 BM blend as the active layer, high power conversion efficiencies of 8.58% and 8.33%, respectively, are achieved, demonstrating that the two hydrophilic polymers are excellent interlayers for efficient inverted polymer solar cells.

  5. Liquid scintillators with near infrared emission based on organoboron conjugated polymers.

    PubMed

    Tanaka, Kazuo; Yanagida, Takayuki; Yamane, Honami; Hirose, Amane; Yoshii, Ryousuke; Chujo, Yoshiki

    2015-11-15

    The organic liquid scintillators based on the emissive polymers are reported. A series of conjugated polymers containing organoboron complexes which show the luminescence in the near infrared (NIR) region were synthesized. The polymers showed good solubility in common organic solvents. From the comparison of the luminescent properties of the synthesized polymers between optical and radiation excitation, similar emission bands were detected. In addition, less significant degradation was observed. These data propose that the organoboron conjugated polymers are attractive platforms to work as an organic liquid scintillator with the emission in the NIR region.

  6. Pentafluorophenyl ester-functionalized phosphorylcholine polymers: preparation of linear, two-arm, and grafted polymer-protein conjugates.

    PubMed

    McRae, Samantha; Chen, Xiangji; Kratz, Katrina; Samanta, Debasis; Henchey, Elizabeth; Schneider, Sallie; Emrick, Todd

    2012-07-09

    Novel pentafluorophenyl (PFP)-ester-functionalized phosphorylcholine (PC) polymers of different architectures were prepared and conjugated to lysozyme as a model protein. Linear and two-arm poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC) structures containing PFP functionality at the chain-end were prepared by atom transfer radical polymerization (ATRP) from novel initiators. Additional conjugates were prepared from phosphorylcholine-substituted cyclooctene (PC-COE) polymers containing PFP-ester bearing comonomers. The polymer-protein conjugates were characterized by HPLC, FPLC, and DLS and were seen to retain most (~80% or greater) of their native enzymatic activity. Pharmacokinetic profiles of the polymer-protein conjugates were studied in mice and found to increase the circulation half-life compared with lysozyme alone.

  7. Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells.

    PubMed

    Li, Guangwu; Kang, Chong; Li, Cuihong; Lu, Zhen; Zhang, Jicheng; Gong, Xue; Zhao, Guangyao; Dong, Huanli; Hu, Wenping; Bo, Zhishan

    2014-06-01

    Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs.

  8. Antimicrobial polymer films for food packaging

    NASA Astrophysics Data System (ADS)

    Concilio, S.; Piotto, S.; Sessa, L.; Iannelli, P.; Porta, A.; Calabrese, E. C.; Galdi, M. R.; Incarnato, L.

    2012-07-01

    New antimicrobial polymeric systems were realized introducing new antimicrobial azo compounds in PP and LDPE matrices. The polymeric materials containing different percentage of azo compounds were mold-casted and the obtained film were tested in vitro against Gram+ and Gram- bacteria and fungi. These results hold promise for the fabrication of bacteria-resistant polymer films by means of simple melt processing with antimicrobial azo-dyes.

  9. Diffusion of small particles in polymer films

    NASA Astrophysics Data System (ADS)

    Polanowski, Piotr; Sikorski, Andrzej

    2017-07-01

    The motion of small probe molecules in a two-dimensional system containing frozen polymer chains was studied by means of Monte Carlo simulations. The model macromolecules were coarse-grained and restricted to vertices of a triangular lattice. The cooperative motion algorithm was used to generate representative configurations of macromolecular systems of different polymer concentrations. The remaining unoccupied lattice sites of the system were filled with small molecules. The structure of the polymer film, especially near the percolation threshold, was determined. The dynamic lattice liquid algorithm was then employed for studies of the dynamics of small objects in the polymer matrix. The influence of chain length and polymer concentration on the mobility and the character of motion of small molecules were studied. Short- and long-time dynamic behaviors of solvent molecules were also described. Conditions of anomalous diffusions' appearance in such systems are discussed. The influence of the structure of the matrix of obstacles on the molecular transport was discussed.

  10. Charge separation and transport in conjugated-polymer/semiconductor-nanocrystal composites studied by photoluminescence quenching and photoconductivity

    SciTech Connect

    Greenham, N.C.; Peng, X.; Alivisatos, A.P.

    1996-12-01

    We study the processes of charge separation and transport in composite materials formed by mixing cadmium selenide or cadmium sulfide nanocrystals with the conjugated polymer poly(2-methoxy,5-(2{prime}-ethyl)-hexyloxy-{ital p}-phenylenevinylene) (MEH-PPV). When the surface of the nanocrystals is treated so as to remove the surface ligand, we find that the polymer photoluminescence is quenched, consistent with rapid charge separation at the polymer/nanocrystal interface. Transmission electron microscopy of these quantum-dot/conjugated-polymer composites shows clear evidence for phase segregation with length scales in the range 10{endash}200 nm, providing a large area of interface for charge separation to occur. Thin-film photovoltaic devices using the composite materials show quantum efficiencies that are significantly improved over those for pure polymer devices, consistent with improved charge separation. At high concentrations of nanocrystals, where both the nanocrystal and polymer components provide continuous pathways to the electrodes, we find quantum efficiencies of up to 12{percent}. We describe a simple model to explain the recombination in these devices, and show how the absorption, charge separation, and transport properties of the composites can be controlled by changing the size, material, and surface ligands of the nanocrystals. {copyright} {ital 1996 The American Physical Society.}

  11. Hydrochromic conjugated polymers for human sweat pore mapping

    PubMed Central

    Lee, Joosub; Pyo, Minkyeong; Lee, Sang-hwa; Kim, Jaeyong; Ra, Moonsoo; Kim, Whoi-Yul; Park, Bum Jun; Lee, Chan Woo; Kim, Jong-Man

    2014-01-01

    Hydrochromic materials have been actively investigated in the context of humidity sensing and measuring water contents in organic solvents. Here we report a sensor system that undergoes a brilliant blue-to-red colour transition as well as ‘Turn-On’ fluorescence upon exposure to water. Introduction of a hygroscopic element into a supramolecularly assembled polydiacetylene results in a hydrochromic conjugated polymer that is rapidly responsive (<20 μs), spin-coatable and inkjet-compatible. Importantly, the hydrochromic sensor is found to be suitable for mapping human sweat pores. The exceedingly small quantities (sub-nanolitre) of water secreted from sweat pores are sufficient to promote an instantaneous colorimetric transition of the polymer. As a result, the sensor can be used to construct a precise map of active sweat pores on fingertips. The sensor technology, developed in this study, has the potential of serving as new method for fingerprint analysis and for the clinical diagnosis of malfunctioning sweat pores. PMID:24781362

  12. Photorefractivity in liquid crystals doped with a soluble conjugated polymer.

    SciTech Connect

    Niemczyk, M. P.; Svec, W. A.; Wasielewski, M. R.; Wiederrecht, G. P.

    1999-07-07

    Photoconductive polymers are doped into liquid crystals to create a new mechanism for space-charge field formation in photorefractive liquid crystal composites. The composites contain poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV) and the electron acceptor N,N{prime}-dioctyl-1,4:5,8-naphthalenediimide, NI. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 {micro}m. We show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile species due to hole migration along the BEH-PPV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.

  13. Hyper-efficient quenching of non-conjugated pendant polymer by silver nanoparticles: A demonstration and versatile mechanistic proposition

    NASA Astrophysics Data System (ADS)

    Ghosh, Debanjana; Chattopadhyay, Nitin

    2012-04-01

    Hyper-efficient quenching of fluorescence of non-conjugated polymer poly(N-vinylcarbazole) by silver nanoparticles is demonstrated. The quenching efficiency increases with an increase in the length of the polymer chain containing the pendant chromophore units. The Stern-Volmer constants (109-1010 mol-1 dm3) are found to be orders of magnitude higher than the normal photochemical quenching processes. Although nanoparticle induced hyper-quenching is reported for conjugated polymers, similar observation in non-conjugated polymers is unprecedented. A versatile mechanism is proposed that rationalizes the hyper-quenching of both conjugated and non-conjugated polymers.

  14. Low dose ionizing radiation detection using conjugated polymers

    SciTech Connect

    Silva, E.A.B.; Borin, J.F.; Nicolucci, P.; Graeff, C.F.O.; Netto, T. Ghilardi; Bianchi, R.F.

    2005-03-28

    In this work, the effect of gamma radiation on the optical properties of poly[2-methoxy-5-(2{sup '}-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) is studied. The samples were irradiated at room temperature with different doses from 0 Gy to 152 Gy using a {sup 60}Co gamma ray source. For thin films, significant changes in the UV-visible spectra were only observed at high doses (>1 kGy). In solution, shifts in absorption peaks are observed at low doses (<10 Gy), linearly dependent on dose. The shifts are explained by conjugation reduction, and possible causes are discussed. Our results indicate that MEH-PPV solution can be used as a dosimeter adequate for medical applications.

  15. Engineered Polymer-Transferrin Conjugates as Self-Assembling Targeted Drug Delivery Systems.

    PubMed

    Makwana, Hiteshri; Mastrotto, Francesca; Magnusson, Johannes Pall; Sleep, Darrell; Hay, Joanna; Nicholls, Karl J; Allen, Stephanie; Alexander, Cameron

    2017-03-28

    Polymer-protein conjugates can be engineered to self-assemble into discrete and well-defined drug delivery systems which combine the advantages of receptor targeting and controlled drug release. We designed specific conjugates of the iron-binding and transport protein, transferrin (Tf), to combine the advantages of this serum-stable protein as a targeting agent for cancer cells with self-assembling polymers to act as carriers of cytotoxic drugs. Tf variants were expressed with cysteine residues at sites spanning different regions of the protein surface and the polymer conjugates grown from these variants were compared with polymer conjugates grown from non-selectively derivatised sites on native Tf. The resulting synthetic biopolymer hybrids were evaluated for self-assembly properties, size and topology, ability to carry an anti-cancer drug (paclitaxel) and cytotoxicity with and without a drug payload in a representative human colon cancer cell line. The results demonstrated that the engineered Tf variant polymer conjugates formed better-defined self-assembled nanoparticles than the non-selectively derivatised conjugates and showed greater efficacy in paclitaxel delivery. A polymer conjugate grown from a specific Tf variant, S415C was found to be taken up rapidly into cancer cells expressing the Tf-receptor, and, while tolerated well by cells in the absence of drugs, was as cytotoxic as free paclitaxel when loaded with the drug. Importantly, the S415C conjugate polymer was not the most active variant in Tf-receptor binding, suggesting that the nanoscale self-assembly of the polymer-protein hybrid is also a key factor in delivery efficacy. The data overall suggest new design rules for polymer-biopolymer hybrids and therapeutic delivery systems which include engineering specific residues for conjugation which mediate nanoscale assembly as well as control of ligand-receptor interactions to target specific cell types.

  16. Oriented thin films of perylenetetracarboxylic diimide on frictiontransferred polymer films

    NASA Astrophysics Data System (ADS)

    Tanigaki, Nobutaka; Heck, Claire; Mizokuro, Toshiko

    Perylenetetracarboxylic diimide (PTCDI) is a promising material for application in organic electronics. In this study we report on the preparation of oriented thin films of PTCDI on the surface of oriented polymer substrates, which were prepared by friction transfer method. Two polymers, poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene) (PPP) were used as the orienting substrate for PTCDI for comparison studies. Characterization by polarized UV-vis absorption shows that the orienting ability of PPP is larger than that of PTFE substrate. Furthermore, polarization-sensitive photoelectric conversion devices were fabricated by using the oriented PTCDI thin film on the PPP substrate.

  17. Characterization of Nanostructured Polymer Films

    DTIC Science & Technology

    2014-12-23

    MAPLE- deposited polymer nanoglobules within the context of the Zhigilei model of target ablation in the MAPLE process. Molecular dynamics... vapor deposition . Figure 7: (a) Normalized volume of polymer nanodroplets and MAPLE- deposited nanoglobules as a function of temperature for...C.L. Sosa, C.B. Arnold, R.D. Priestley*, Patchy Janus Particles with Tunable Roughness and Composition via Vapor -Assisted Deposition of Macromolecules

  18. Molecular design toward highly efficient photovoltaic polymers based on two-dimensional conjugated benzodithiophene.

    PubMed

    Ye, Long; Zhang, Shaoqing; Huo, Lijun; Zhang, Maojie; Hou, Jianhui

    2014-05-20

    As researchers continue to develop new organic materials for solar cells, benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers have come to the fore. To improve the photovoltaic properties of BDT-based polymers, researchers have developed and applied various strategies leading to the successful molecular design of highly efficient photovoltaic polymers. Novel polymer materials composed of two-dimensional conjugated BDT (2D-conjugated BDT) have boosted the power conversion efficiency of polymer solar cells (PSCs) to levels that exceed 9%. In this Account, we summarize recent progress related to the design and synthesis of 2D-conjugated BDT-based polymers and discuss their applications in highly efficient photovoltaic devices. We introduce the basic considerations for the construction of 2D-conjugated BDT-based polymers and systematic molecular design guidelines. For example, simply modifying an alkoxyl-substituted BDT to form an alkylthienyl-substituted BDT can improve the polymer hole mobilities substantially with little effect on their molecular energy level. Secondly, the addition of a variety of chemical moieties to the polymer can produce a 2D-conjugated BDT unit with more functions. For example, the introduction of a conjugated side chain with electron deficient groups (such as para-alkyl-phenyl, meta-alkoxyl-phenyl, and 2-alkyl-3-fluoro-thienyl) allowed us to modulate the molecular energy levels of 2D-conjugated BDT-based polymers. Through the rational design of BDT analogues such as dithienobenzodithiophene (DTBDT) or the insertion of larger π bridges, we can tune the backbone conformations of these polymers and modulate their photovoltaic properties. We also discuss the influence of 2D-conjugated BDT on polymer morphology and the blends of these polymers with phenyl-C61 (or C71)-butyric acid methyl ester (PCBM). Finally, we summarize the various applications of the 2D-conjugated BDT-based polymers in highly efficient PSC devices. Overall, this Account

  19. Conjugated polymer-fullerene blend with strong optical limiting in the near-infrared.

    PubMed

    Chi, San-Hui; Hales, Joel M; Cozzuol, Matteo; Ochoa, Charles; Fitzpatrick, Madison; Perry, Joseph W

    2009-11-23

    Optical-quality, melt processable thick films of a conjugated polymer blend containing poly(2-methoxy-5-(2-ethyl-hexyloxy)-(phenylene vinylene)) (MEH-PPV), a C(60) derivative (PCBM) and a plasticizer (1,2-di-iso-octylphthalate) have been developed and their nonlinear absorption and optical limiting properties have been investigated. These blend materials exhibited strong optical limiting characteristics in the near infrared region (750-900 nm), with broad temporal dynamic range spanning femtosecond to nanosecond pulse widths. The dispersion of the optical limiting figure-of-merit of the MEH-PPV:PCBM:DOP blend shows a peak near the wavelength of the MEH-PPV cation, indicating an important role of one-photon and two-photon induced charge transfer in the nonlinear absorption response.

  20. Directed Assembly of Nanofilled Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Karim, Alamgir

    Facile directed self-assembly (DSA) of multicomponent thin films is important for potential technological applications. This requires a fine control of a complex interplay of processing parameters that need to be properly optimized for different organized structures. This talk will discuss some of our recent success towards realizing tunable DSA of soft matter multicomponent systems involving a dispersion of polymer-grafted nanoparticles in block copolymer or homopolymer matrices. DSA methods for such multicomponent films will be discussed. These include the use of zone-annealing with soft-shear to create highly anisotropic nanoparticle arrays, while direct immersion annealing (DIA) has been used to order nanoparticle filled films by dipping the films into controlled solvent quality solvent mixtures. A recently observed phenomena of confinement driven entropic order and phase segregation of polymer grafted nanoparticles in similar and dissimilar polymer matrices in melt state will be discussed. A high density of nano particles of different types ranging from metallic to inorganic to organic were patterned almost exclusively into channels via topographical soft confinement using entropic forces. Enthalpic interactions between the nanoparticle grafted layer and the polymer matrix could be used as a further handle to tune the directed assembly of the nanoparticles. The phenomena will be discussed in terms of confinement parameters, partition coefficient, free energy gain and entropic versus enthalpic interactions.

  1. Photovoltaic properties of polymer films

    NASA Astrophysics Data System (ADS)

    Reucroft, P. J.; Ullal, H.

    1980-03-01

    The effect of metal electrode and film thickness on the photovoltaic energy conversion efficiency in (1:1) mole ratio films of poly (N-vinylcarbazole) (PVK) and 2,4,7-trinitrofluorenone (TNF) has been investigated. Low work function metals increase the Schottky barrier height which leads to increases in the photovoltaic energy conversion efficiency. A ten-fold decrease in film thickness produces a thousand-fold increase in photovoltaic energy conversion efficiency. A theoretical model which assumes that the photovoltaic current is limited by Child's law predicts photovoltaic efficiencies which are in good agreement with the measured efficiencies.

  2. Electrochemical Analysis of Conducting Polymer Thin Films

    PubMed Central

    Vyas, Ritesh N.; Wang, Bin

    2010-01-01

    Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. PMID:20480052

  3. Inorganic-polymer-derived dielectric films

    DOEpatents

    Brinker, C. Jeffrey; Keefer, Keith D.; Lenahan, Patrick M.

    1987-01-01

    A method of coating a substrate with a thin film of a polymer of predetermined porosity comprises depositing the thin film on the substrate from a non-gelled solution comprising at least one hydrolyzable metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base, prior to depositing the film, controlling the structure of the polymer for a given composition of the solution exclusive of the acid or base component and the water component, (a) by adjusting each of the water content, the pH, and the temperature to obtain the desired concentration of alkoxide, and then adjusting the time of standing of the solution prior to lowering the temperature of the solution, and (b) lowering the temperature of the solution after the time of standing to about 15 degrees C. or lower to trap the solution in a state in which, after the depositing step, a coating of the desired porosity will be obtained, and curing the deposited film at a temperature effective for curing whereby there is obtained a thin film of a polymer of a predetermined porosity and corresponding pore size on the substrate.

  4. Highly Sensitive Flexible NH3 Sensors Based on Printed Organic Transistors with Fluorinated Conjugated Polymers.

    PubMed

    Nketia-Yawson, Benjamin; Jung, A-Ra; Noh, Yohan; Ryu, Gi-Seong; Tabi, Grace Dansoa; Lee, Kyung-Koo; Kim, BongSoo; Noh, Yong-Young

    2017-03-01

    Understanding the sensing mechanism in organic chemical sensors is essential for improving the sensing performance such as detection limit, sensitivity, and other response/recovery time, selectivity, and reversibility for real applications. Here, we report a highly sensitive printed ammonia (NH3) gas sensor based on organic thin film transistors (OTFTs) with fluorinated difluorobenzothiadiazole-dithienosilole polymer (PDFDT). These sensors detected NH3 down to 1 ppm with high sensitivity (up to 56%) using bar-coated ultrathin (<4 nm) PDFDT layers without using any receptor additives. The sensing mechanism was confirmed by cyclic voltammetry, hydrogen/fluorine nuclear magnetic resonance, and UV/visible absorption spectroscopy. PDFDT-NH3 interactions comprise hydrogen bonds and electrostatic interactions between the PDFDT polymer backbone and NH3 gas molecules, thus lowering the highest occupied molecular orbital levels, leading to hole trapping in the OTFT sensors. Additionally, density functional theory calculations show that gaseous NH3 molecules are captured via cooperation of fluorine atoms and dithienosilole units in PDFDT. We verified that incorporation of functional groups that interact with a specific gas molecule in a conjugated polymer is a promising strategy for producing high-performance printed OTFT gas sensors.

  5. Tuning the entropic spring to dictate order and functionality in polymer conjugated peptide biomaterials

    NASA Astrophysics Data System (ADS)

    Keten, Sinan

    Hybrid peptide-polymer conjugates have the potential to combine the advantages of natural proteins and synthetic polymers, resulting in biomaterials with improved stability, controlled assembly, and tailored functionalities. However, the effect of polymer conjugation on peptide structural organization and functionality, along with the behavior of polymers at the interface with biomolecules remain to be fully understood. This talk will summarize our recent efforts towards establishing a modeling framework to design entropic forces in helix-polymer conjugates and polymer-conjugated peptide nanotubes to achieve hierarchical self-assembling systems with predictable order. The first part of the talk will discuss how self-assembly principles found in biology, combined with polymer physics concepts can be used to create artificial membranes that mimic certain features of ion channels. Thermodynamics and kinetics aspects of self-assembly and how it governs the growth and stacking sequences of peptide nanotubes will be discussed, along with its implications for nanoscale transport. The second part of the talk will review advances related to modeling polymer conjugated coiled coils at relevant length and time scales. Atomistic simulations combined with sampling techniques will be presented to discuss the energy landscapes governing coiled-coil stability, revealing cascades of events governing disassembly. This will be followed by a discussion of mechanisms through which polymers can stabilize small proteins, such as shielding of solvents, and how specific peptide sequences can reciprocate by altering polymer conformations. Correlations between mechanical and thermal stability of peptides will be discussed. Finally, coarse-grained simulations will provide insight into how the location of polymer attachment changes entropic forces and higher-level organization in helix bundle assemblies. Our findings set the stage for a materials-by-design capability towards dictating complex

  6. Benzophenone as a photoprobe of polymer films

    NASA Astrophysics Data System (ADS)

    Levin, Peter P.; Efremkin, Alexei F.; Khudyakov, Igor V.

    2017-09-01

    The review article is devoted to kinetics of fast reactions following photoexcitation of benzophenone in polymer films. We observed three processes by ns laser flash photolysis in elastomers: (i) decay of a triple state of benzophenone with hydrogen abstraction from polymer matrix, (ii) formation and decay of geminate radical pairs, (iii) cross-termination of the formed radicals in the polymer bulk. Application of external magnetic field (MF) of B = 0.2 T essentially affects recombination of geminate (G-) and a bimolecular recombination of free radicals, which escaped polymer cage (F-pairs). Theoretical calculation of MF effects on G- and F-pairs is in agreement with corresponding experimental data. Elongation of elastomer leads to an unexpected observation: recombination in the bulk becomes slower. An explanation of this phenomenon based on elastomer free volume Vf approach was suggested.

  7. "Bio"-macromolecules: polymer-protein conjugates as emerging scaffolds for therapeutics.

    PubMed

    Borchmann, Dorothee E; Carberry, Tom P; Weck, Marcus

    2014-01-01

    Polymer-protein conjugates are biohybrid macromolecules derived from covalently connecting synthetic polymers with polypeptides. The resulting materials combine the properties of both worlds: chemists can engineer polymers to stabilize proteins, to add functionality, or to enhance activity; whereas biochemists can exploit the specificity and complexity that Nature has bestowed upon its macromolecules. This has led to a wealth of applications, particularly within the realm of biomedicine. Polymer-protein conjugation has expanded to include scaffolds for drug delivery, tissue engineering, and microbial inhibitors. This feature article reflects upon recent developments in the field and discusses the applications of these hybrids from a biomaterials standpoint.

  8. Theory of optical transitions in conjugated polymers. I. Ideal systems

    SciTech Connect

    Barford, William; Marcus, Max

    2014-10-28

    We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑{sub n}|Ψ{sub n}|{sup 4}){sup −1}, where Ψ{sub n} is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F{sub 0v}(N) = S(N){sup v}exp ( − S(N))/v! for the vth vibronic manifold. We show that the 0 − 0 and 0 − 1 optical intensities are proportional to F{sub 00}(N) and F{sub 01}(N), respectively, and thus the ratio of the 0 − 1 to 0 − 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the

  9. Porous Polyolefin Films via Polymer Blends

    NASA Astrophysics Data System (ADS)

    Macosko, Chris

    Porous polymer films have broad application including battery separators, membrane supports and filters. Polyolefins are attractive for these applications because of their solvent resistance, low electrical and thermal conductivity, easy fabrication and cost. We will describe fabrication of porous films using cocontinuous blends of a polyolefin with another polymer which can be readily removed with a solvent. Methods to image and control the cocontinuous morphology will be presented.Bell, J. R., K. Chang, C. R. Lopez-Barron, C. W. Macosko, and D. C. Morse, ''Annealing of cocontinuous polymer blends: effect of block copolymer molecular weight and architecture,'' Macromolecules 43, 5024-5032 (2010).Lopez-Barron, C. R., and C. W. Macosko, ''Direct measurement of interface anisotropy of bicontinuous structures via 3D image analysis,'' Langmuir 26, 14284-14293 (2010).Trifkovic, M., A. T. Hedegaard, K. Huston, M. Sheikhzadeh, and C. W. Macosko, ''Porous films via PE/PEO cocontinuous blends,'' Macromolecules 45, 6036-6044 (2012).Hedegaard, A.T., L.L. Gu and C. W. Macosko, ``Effect of Extensional Viscosity on Cocontinuity of Immiscible Polymer Blends'' J. Rheol. 59, 1397-1417 (2015).

  10. Membranes and Films from Polymers.

    ERIC Educational Resources Information Center

    Blumberg, Avrom A.

    1986-01-01

    Provides background information on polymeric films and membranes including production methods, special industrial and medical applications, laboratory preparation, and an experimental investigation of a porous cellulose acetate membrane. Presents a demonstration to distinguish between high- and low-density polyethylene. (JM)

  11. Membranes and Films from Polymers.

    ERIC Educational Resources Information Center

    Blumberg, Avrom A.

    1986-01-01

    Provides background information on polymeric films and membranes including production methods, special industrial and medical applications, laboratory preparation, and an experimental investigation of a porous cellulose acetate membrane. Presents a demonstration to distinguish between high- and low-density polyethylene. (JM)

  12. Vapor deposition routes to conformal polymer thin films

    PubMed Central

    Moni, Priya; Al-Obeidi, Ahmed

    2017-01-01

    Vapor phase syntheses, including parylene chemical vapor deposition (CVD) and initiated CVD, enable the deposition of conformal polymer thin films to benefit a diverse array of applications. This short review for nanotechnologists, including those new to vapor deposition methods, covers the basic theory in designing a conformal polymer film vapor deposition, sample preparation and imaging techniques to assess film conformality, and several applications that have benefited from vapor deposited, conformal polymer thin films. PMID:28487816

  13. MISSE 6 Polymer Film Tensile Experiment

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K. R.; Dever, Joyce A.; Banks, Bruce A.; Waters, Deborah L.; Sechkar, Edward; Kline, Sara

    2010-01-01

    The Polymer Film Tensile Experiment (PFTE) was flown as part of Materials International Space Station Experiment 6 (MISSE 6). The purpose of the experiment was to expose a variety of polymer films to the low Earth orbital environment under both relaxed and tension conditions. The polymers selected are those commonly used for spacecraft thermal control and those under consideration for use in spacecraft applications such as sunshields, solar sails, and inflatable and deployable structures. The dog-bone shaped samples of polymers that were flown were exposed on both the side of the MISSE 6 Passive Experiment Container (PEC) that was facing into the ram direction (receiving atomic oxygen, ultraviolet (UV) radiation, ionizing radiation, and thermal cycling) and the wake facing side (which was supposed to have experienced predominantly the same environmental effects except for atomic oxygen which was present due to reorientation of the International Space Station). A few of the tensile samples were coated with vapor deposited aluminum on the back and wired to determine the point in the flight when the tensile sample broke as recorded by a change in voltage that was stored on battery powered data loggers for post flight retrieval and analysis. The data returned on the data loggers was not usable. However, post retrieval observation and analysis of the samples was performed. This paper describes the preliminary analysis and observations of the polymers exposed on the MISSE 6 PFTE.

  14. Enhancing performance characteristics of organic semiconducting films by improved solution processing

    DOEpatents

    Bazan, Guillermo C [Santa Barbara, CA; Heeger, Alan J [Santa Barbara, CA; Moses, Daniel [Santa Barbara, CA; Peet, Jeffrey [Goleta, CA

    2013-09-25

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  15. Enhancing performing characteristics of organic semiconducting films by improved solution processing

    SciTech Connect

    Bazan, Guillermo C; Moses, Daniel; Peet, Jeffrey; Heeger, Alan J

    2014-05-13

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  16. Enhancing performance characteristics of organic semiconducting films by improved solution processing

    DOEpatents

    Bazan, Guillermo C; Mikhailovsky, Alexander; Moses, Daniel; Nguyen, Thuc-Quyen; Peet, Jeffrey; Soci, Cesare

    2012-11-27

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  17. Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

    PubMed Central

    Daneshvar, Eugene Dariush; Smela, Elisabeth

    2014-01-01

    Conjugated polymer actuators have potential use in implantable neural interface devices for modulating the position of electrode sites within brain tissue or guiding insertion of neural probes along curved trajectories. The actuation of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) was characterized to ascertain whether it could be employed in the cerebral environment. Microfabricated bilayer beams were electrochemically cycled at either 22 or 37 °C in aqueous NaDBS or in artificial cerebrospinal fluid (aCSF). Nearly all the ions in aCSF were exchanged into the PPy – the cations Na+, K+, Mg2+, Ca2+, as well as the anion PO43−; Cl− was not present. Nevertheless, deflections in aCSF were comparable to those in NaDBS and they were monotonic with oxidation level: strain increased upon reduction, with no reversal of motion despite the mixture of ionic charges and valences being exchanged. Actuation depended on temperature. Upon warming, the cyclic voltammograms showed additional peaks and an increase of 70% in the consumed charge. Bending was, however, much less affected: strain increased somewhat (6-13%) but remained monotonic, and deflections shifted (up to 20%). These results show how the actuation environment must be taken into account, and demonstrate proof of concept for actuated implantable neural interfaces. PMID:24574101

  18. Polarons in π-Conjugated Polymers: Anderson or Landau?

    PubMed

    Barford, William; Marcus, Max; Tozer, Oliver Robert

    2016-02-04

    Using both analytical expressions and the density matrix renormalization group method, we study the fully quantized disordered Holstein model to investigate the localization of charges and excitons by vibrational or torsional modes-i.e., the formation of polarons-in conformationally disordered π-conjugated polymers. We identify two distinct mechanisms for polaron formation, namely Anderson localization via disorder (causing the formation of Anderson polarons) and self-localization by self-trapping via normal modes (causing the formation of Landau polarons). We identify the regimes where either description is more valid. The key distinction between Anderson and Landau polarons is that for the latter the particle wave function is a strong function of the normal coordinates, and hence the "vertical" and "relaxed" wave functions are different. This has theoretical and experimental consequences for Landau polarons. Theoretically, it means that the Condon approximation is not valid, and so care needs to be taken when evaluating transition rates. Experimentally, it means that the self-localization of the particle as a consequence of its coupling to the normal coordinates may lead to experimental observables, e.g., ultrafast fluorescence depolarization. We apply these ideas to poly(p-phenylenevinylene). We show that the high frequency C-C bond oscillation only causes Landau polarons for a very narrow parameter regime; generally we expect disorder to dominate and Anderson polarons to be a more applicable description. Similarly, for the low frequency torsional fluctuations we show that Anderson polarons are expected for realistic parameters.

  19. Tracking the coherent generation of polaron pairs in conjugated polymers

    PubMed Central

    De Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F.; Plenio, Martin B.; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

    2016-01-01

    The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials. PMID:27929115

  20. Tracking the coherent generation of polaron pairs in conjugated polymers.

    PubMed

    De Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F; Plenio, Martin B; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

    2016-12-08

    The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials.

  1. Photocatalysts Based on Cobalt-chelating Conjugated Polymers for Hydrogen Evolution from Water

    SciTech Connect

    Li, Lianwei; Hadt, Ryan G.; Yao, Shiyu; Lo, Waiyip; Cai, Zhengxu; Wu, Qingliu; Pandit, Bill; Chen, Lin X.; Yu, Luping

    2016-08-09

    Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Four conjugated polymers chelated with earth abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as light-harvesting antenna and electron transfer conduit with the in-chain bipyridyl chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents, enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.

  2. Thin Polymer Films Containing Carbon Nanostructures

    NASA Astrophysics Data System (ADS)

    Paszkiewicz, S.; Piesowicz, E.; Irska, I.; Roslaniec, Z.; Szymczyk, A.; Pawelec, I.

    2016-05-01

    Within the framework of the presented paper, the research experiments were conducted on the preparation and characterization of polymer thin films containing carbon nanotubes, graphene derivatives and hybrid systems of both CNTs/graphene derivatives, in which condensation polymers constituted the matrix. The use of in situ synthesis allowed to obtain nanocomposites with a high degree of homogeneity, which is a key issue for further industrial applications, while the analysis of the physical properties of the obtained materials showed effect of the addition of carbon nanotubes and graphene derivatives on their structure, barrier properties and thermal and electrical conductivity.

  3. Polarity engineering of conjugated polymers by variation of chemical linkages connecting conjugated backbones.

    PubMed

    Yun, Hui-Jun; Choi, Hyun Ho; Kwon, Soon-Ki; Kim, Yun-Hi; Cho, Kilwon

    2015-03-18

    The fine tuning of the dominant polarity in polymer semiconductors is a key issue for high-performance organic complementary circuits. In this paper, we demonstrate a new methodology for addressing this issue in terms of molecular design. In an alternating conjugated donor-acceptor copolymer system, we systematically engineered the chemical linkages that connect the aromatic units in donor moieties. Three donor moieties, thiophene-vinylene-thiophene (TVT), thiophene-acetylene-thiophene (TAT), and thiophene-cyanovinylene-thiophene (TCNT), were combined with an acceptor moiety, thienoisoindigo (TIID), and finally, three novel TIID-based copolymers were synthesized: PTIID-TVT, PTIID-TAT, and PTIID-TCNT. We found that the vinylene, acetylene, and cyanovinylene linkages decisively affect the energy structure, molecular orbital delocalization, microstructure, and, most importantly, the dominant polarity of the polymers. The vinylene-linked PTIID-TVT field-effect transistors (FETs) exhibited intrinsic hole and electron mobilities of 0.12 and 1.5 × 10(-3) cm(2) V(-1 )s(-1), respectively. By contrast, the acetylene-linked PTIID-TAT FETs exhibited significantly improved intrinsic hole and electron mobilities of 0.38 and 0.03 cm(2) V(-1) s(-1), respectively. Interestingly, cyanovinylene-linked PTIID-TCNT FETs exhibited reverse polarity, with hole and electron mobilities of 0.07 and 0.19 cm(2) V(-1) s(-1). As a result, the polarity balance, which is quantified as the electron/hole mobility ratio, was dramatically tuned from 0.01 to 2.7. Our finding demonstrates a new methodology for the molecular design of high-performance organic complementary circuits.

  4. Multifunctional polymer-metal nanocomposites via direct chemical reduction by conjugated polymers.

    PubMed

    Xu, Ping; Han, Xijiang; Zhang, Bin; Du, Yunchen; Wang, Hsing-Lin

    2014-03-07

    Noble metal nanoparticles (MNPs) have attracted continuous attention due to their promising applications in chemistry, physics, bioscience, medicine and materials science. As an alternative to conventional solution chemistry routes, MNPs can be directly synthesized through a conjugated polymer (CP) mediated technique utilizing the redox chemistry of CPs to chemically reduce the metal ions and modulate the size, morphology, and structure of the MNPs. The as-prepared multifunctional CP-MNP nanocomposites have shown application potentials as highly sensitive surface enhanced Raman spectroscopy (SERS) substrates, effective heterogeneous catalysts for organic synthesis and electrochemistry, and key components for electronic and sensing devices. In this tutorial review, we begin with a brief introduction to the chemical nature and redox properties of CPs that enable the spontaneous reduction of noble metal ions to form MNPs. We then focus on recent progress in control over the size, morphology and structure of MNPs during the conjugated polymer mediated syntheses of CP-MNP nanocomposites. Finally, we highlight the multifunctional CP-MNP nanocomposites toward their applications in sensing, catalysis, and electronic devices.

  5. Conjugation length dependent transport in conducting polymers from a resistor network model

    NASA Astrophysics Data System (ADS)

    Baughman, R. H.; Shacklette, L. W.

    1989-06-01

    The effect of conjugation length (L) upon electronic conductivity components of conducting polymers is derived using a generalized resistor network model. Results are obtained for polymers which contain a statistical distribution of defects which limit conjugation, as well as for regular copolymers which have a fixed phase relationship between interruptions in conjugation on neighboring chains. The short-conjugation-length limits of the derived equations are identical with those previously obtained by evaluating molecular aspects of charge transfer. More specifically, when interchain transport fully limits both chain-direction conductivity (σ1) and an orthogonal conductivity (σ2), the calculated electrical anisotropy is σ1/σ2=L2/6d2F, where d is the interchain separation in a hopping direction, and the product d2F is the mean square average projection of the interchain vector on the electric field direction. The present analysis extends predictive capabilities over the entire range from short conjugation lengths to infinite conjugation lengths. For long conjugation lengths terminated by effectively infinite barrier defects, σ1/σ1(∞) and σ2/σ2(∞) are calculated from the parameters which define polymer structure and, for the former ratio, the ratio of infinite chain conductivities parallel [σ1(∞)] and orthogonal [σ2(∞)] to the chains. A general relationship, appropriate for a still wider range of conjugation lengths, is derived between σ1/σ1(∞) and [σ2/σ1(∞)]1/2(L/d)/F1/2, where the geometrical parameter F is of order unity in directions of high σ2. Using this relationship for a polymer of known structure, the chain-direction electrical conductivity in the infinite-chain limit can be derived from measurements of σ1, σ2, and average conjugation length. Good agreement is obtained between the calculated and observed dependence of conductivity upon conjugation length for available polymers, in which bulk conductivity is limited by interchain

  6. High-Field-Effect Mobility of Low-Crystallinity Conjugated Polymers with Localized Aggregates.

    PubMed

    Son, Sung Y; Kim, Yebyeol; Lee, Junwoo; Lee, Gang-Young; Park, Won-Tae; Noh, Yong-Young; Park, Chan E; Park, Taiho

    2016-07-06

    Charge carriers typically move faster in crystalline regions than in amorphous regions in conjugated polymers because polymer chains adopt a regular arrangement resulting in a high degree of π-π stacking in crystalline regions. In contrast, the random polymer chain orientation in amorphous regions hinders connectivity between conjugated backbones; thus, it hinders charge carrier delocalization. Various studies have attempted to enhance charge carrier transport by increasing crystallinity. However, these approaches are inevitably limited by the semicrystalline nature of conjugated polymers. Moreover, high-crystallinity conjugated polymers have proven inadequate for soft electronics applications because of their poor mechanical resilience. Increasing the polymer chain connectivity by forming localized aggregates via π-orbital overlap among several conjugated backbones in amorphous regions provides a more effective approach to efficient charge carrier transport. A simple strategy relying on the density of random copolymer alkyl side chains was developed to generate these localized aggregates. In this strategy, steric hindrance caused by these side chains was modulated to change their density. Interestingly, a random polymer exhibiting low alkyl side chain density and crystallinity displayed greatly enhanced field-effect mobility (1.37 cm(2)/(V·s)) compared with highly crystalline poly(3-hexylthiophene).

  7. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  8. Strong Composition Effects in All-Polymer Phototransistors with Bulk Heterojunction Layers of p-type and n-type Conjugated Polymers.

    PubMed

    Han, Hyemi; Lee, Chulyeon; Kim, Hwajeong; Seo, Jooyeok; Song, Myeonghun; Nam, Sungho; Kim, Youngkyoo

    2017-01-11

    We report the composition effect of polymeric sensing channel layers on the performance of all-polymer phototransistors featuring bulk heterojunction (BHJ) structure of electron-donating (p-type) and electron-accepting (n-type) polymers. As an n-type component, poly(3-hexylthiopehe-co-benzothiadiazole) end-capped with 4-hexylthiophene (THBT-4ht) was synthesized via two-step reactions. A well-studied conjugated polymer, poly(3-hexylthiophene) (P3HT), was employed as a p-type polymer. The composition of BHJ (P3HT:THBT-4ht) films was studied in detail by varying the THBT-4ht contents (0, 1, 3, 5, 10, 20, 30, 40, and 100 wt %). The best charge separation in the P3HT:THBT-4ht films was measured at 30 wt % by the photoluminescence (PL) study, while the charge transport characteristics of devices were improved at the low THBT-4ht contents (<10 wt %). The photosensing experiments revealed that the photosensivity of all-polymer phototransistors was higher than that of the phototransistors with the pristine P3HT layers and strongly dependent on the BHJ composition. The highest (corrected) responsivity (RC) was achieved at 20 wt %, which can be attributable to the balance between the best charge separation and transport states, as investigated for crystal nanostructures and surface morphology by employing synchrotron-radiation grazing-incidence wide-angle X-ray scattering, high-resolution/scanning transmission electron microscopy, and atomic force microscopy.

  9. Affinity separation using an Fv antibody fragment-"smart" polymer conjugate.

    PubMed

    Fong, Robin B; Ding, Zhongli; Hoffman, Allan S; Stayton, Patrick S

    2002-08-05

    Poly(N-isopropylacrylamide), or PNIPAAm, is considered a "smart" polymer because it sharply precipitates when heated above a critical temperature, about 32 degrees C in water, and redissolves when cooled. Conjugates made of PNIPAAm and IgG antibodies also exhibit the same critical temperature behavior. Interestingly, antigens that are complexed with these conjugates can also be phase-separated along with the conjugates. In this work, we conjugated PNIPAAm for the first time to the immunoglobulin Fv fragment, the smallest fragment of an antibody that still retains the antigenic affinity of the whole antibody. For our studies, we used an Fv fragment that strongly binds hen egg white lysozyme (HEL). The purified Fv fragment-polymer conjugate precipitated at the same temperature as did the pure polymer. After addition of the conjugate to a mixture containing HEL and after thermal separation of the conjugate at 37 degrees C, the amount of HEL in solution was reduced by as much as 80%. We were able to demonstrate the reversibility of the separation through three cycles of precipitation and dissolution. It was also possible to recover free HEL by thermal separation of the conjugate in the presence of an eluant, 50 mM diethylamine. The conjugate can then be recycled for second use. In conclusion, immunoseparations can be performed using smart polymer conjugates made with just the variable domains of an antibody. Unlike whole antibodies, fragments of antibodies can be produced in Escherichia coli, allowing easier genetic engineering of the antibody and tailoring of the conjugate.

  10. Suppression of quantum dot blinking in DTT-doped polymer films

    PubMed Central

    Antelman, Josh; Ebenstein, Yuval; Dertinger, Thomas; Michalet, Xavier; Weiss, Shimon

    2009-01-01

    In this report we evaluate the emission properties of single quantum dots embedded in a thin, thiol containing polymer film. We report the suppression of quantum dot blinking leading to a continuous photon flux from both organic and water soluble quantum dots and demonstrate their application as robust fluorescent point sources for ultrahigh resolution localization. In addition, we apply the polymer coating to cell samples immunostained with antibody conjugated QDs and show that fluorescence intensity from the polymer embedded cells shows no sign of degradation after 67 hours of continuous excitation. The reported thin polymer film coating may prove advantageous for immuno-cyto/histo-chemistry as well as for the fabrication of quantum dot containing devices requiring a reliable and stable photon source (including a single photon source) or stable charge characteristics while maintaining intimate contact between the quantum dot and the surrounding matrix. PMID:20161096

  11. Unsubstituted Benzodithiophene-Based Conjugated Polymers for High-Performance Organic Field-Effect Transistors and Organic Solar Cells.

    PubMed

    Chen, Weichao; Xiao, Manjun; Han, Liangliang; Zhang, Jidong; Jiang, Huanxiang; Gu, Chuantao; Shen, Wenfei; Yang, Renqiang

    2016-08-03

    Unsubstituted benzo[1,2-b:4,5-b']dithiophene (BDT) was used to construct a high-performance conjugated polymer with 5,6-difluoro-4,7-bis[4-(2-octyldodecyl)thiophene-2-yl]benzo[c][1,2,5] thiadiazole (DTFFBT), named PBDT-DTFFBT. The polymer shows the low-lying highest occupied molecular orbital (HOMO) energy level (-5.40 eV) and a broad absorption spectra with strong vibronic absorption peak. Pure polymer films exhibit good crystallinity and edge-on orientation, partially attributed to the BDT units without any side chains, and as a result, the corresponding thin-film transistor showed excellent hole mobility over 1 cm(2) V(-1) s(-1). Interestingly, a well-distributed nanofibrillar polymer aggregation with face-on orientation was obviously formed when blending with PC71BM, which was in favor of the charge transportation. Consequently, the bulk heterojunction polymer solar cells based on the blends showed high power conversion efficiency of 9.29% with large short-current density (14.56 mA cm(-2)) and high fill factor (0.751) without any process additives or thermal annealing.

  12. Germanium films by polymer-assisted deposition

    DOEpatents

    Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

    2013-01-15

    Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

  13. The Evolution of Thin-Film Structure in pi-Conjugated System: Implications for Devices

    DTIC Science & Technology

    2015-07-09

    dependent, polymer self - assembly (Chem Matls, 2015). The results provide vital insights into factors leading to organized conjugated polymer nanostructures...34Liquid Crystalline Poly(3-hexylthiophene) Solutions Revisited: Role of Time- dependent Self - Assembly ", Chemistry of Materials (2015), 27(7), 2687-2694...period (if none, report none): For the first time, we demonstrated that π-conjugated polymers self - assemble and exhibit liquid crystal ordering

  14. Z-Group ketone chain transfer agents for RAFT polymer nanoparticle modification via hydrazone conjugation

    PubMed Central

    Bandyopadhyay, Saibal; Xia, Xin; Maiseiyeu, Andrei; Mihai, Georgeta; Rajagopalan, Sanjay

    2012-01-01

    A ketal-containing trithiocarbonyl compound has been synthesized and characterized as a chain transfer agent (CTA) in Reversible Addition Fragmentation Transfer (RAFT) polymerization. The ketal functionality does not interfere with RAFT polymerization of acrylate monomers, which proceeds as previously reported to yield macro-CTA polymers and block co-polymers. Post-polymerization ketal cleavage revealed ketone functionality at the polar terminus of an amphiphilic block co-polymer. Hydrazone-formation was facile in both organic solution as well as in aqueous buffer where polymer nanoparticle assemblies were formed, indicating a conjugation/end-functionalization yield of 40–50%. Conjugation was verified with fluorescein, biotin and Gd-DOTA derivatives, and though the trithiocarbonate linkage is hydrolytically labile, we observed stable conjugation for several days at pH 7.4. and 37°C. As expected, streptavidin binding to biotinylated polymer micelles was observed, and size-change based relaxivity increases were observed when Gd-DOTA hydrazide was conjugated to polymer micelles. Cell-uptake of fluorescently labeled polymer micelles was also readily tracked by FACS and fluorescence microscopy. These polymer derivatives demonstrate a range of potential theranostic/biotechnological applications for this conveniently accessible keto-CTA, which include ligand-based nanoparticle targeting and fluorescent/MR nanoparticle contrast agents. PMID:23148126

  15. Toward anticancer immunotherapeutics: well-defined polymer-antibody conjugates for selective dendritic cell targeting.

    PubMed

    Tappertzhofen, Kristof; Bednarczyk, Monika; Koynov, Kaloian; Bros, Matthias; Grabbe, Stephan; Zentel, Rudolf

    2014-10-01

    This paper describes the synthesis of semitelechelic maleimide-modified N-(2-hydroxypropyl)methacrylamid) (HPMA) based polymers of narrow dispersity that can be conjugated e.g. to anti-DEC-205 antibodies affording "star-like" topologies (one antibody decorated with several polymer chains). FCS revealed a hydrodynamic diameter of R(h)  = 7.9 nm and SEC narrow dispersity (1.45). Primary in vitro studies with bone marrow derived dendritic cells (DC) show higher cellular binding and uptake rates compared to control samples. Moreover, incubating these conjugates to primary splenocytes demonstrates a much higher affinity to the primary DCs than to any other immune cell population within the spleen. This differentiation is, thereby, much more pronounced for the star-like conjugates than for conjugates made from polymers statistically modified with anti-DEC-205. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Conjugated Polymer with Intrinsic Alkyne Units for Synergistically Enhanced Raman Imaging in Living Cells.

    PubMed

    Li, Shengliang; Chen, Tao; Wang, Yunxia; Liu, Libing; Lv, Fengting; Li, Zhiliang; Huang, Yanyi; Schanze, Kirk S; Wang, Shu

    2017-08-29

    Development of Raman-active materials with enhanced and distinctive Raman vibrations in the Raman-silent region (1800-2800 cm(-1) ) is highly required for specific molecular imaging of living cells with high spatial resolution. Herein, water-soluble cationic conjugated polymers (CCPs), poly(phenylene ethynylene) (PPE) derivatives, are explored for use as alkyne-state-dependent Raman probes for living cell imaging due to synergetic enhancement effect of alkyne vibrations in Raman-silent region compared to alkyne-containing small molecules. The enhanced alkyne signals result from the integration of alkyne groups into the rigid backbone and the delocalized π-conjugated structure. PPE-based conjugated polymer nanoparticles (CPNs) were also prepared as Raman-responsive nanomaterials for distinct imaging application. This work opens a new way into the development of conjugated polymer materials for enhanced Raman imaging. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Effect of polymer aggregation on the open circuit voltage in organic photovoltaic cells: aggregation-induced conjugated polymer gel and its application for preventing open circuit voltage drop.

    PubMed

    Kim, Bong-Gi; Jeong, Eun Jeong; Park, Hui Joon; Bilby, David; Guo, L Jay; Kim, Jinsang

    2011-03-01

    To investigate the structure-dependent aggregation behavior of conjugated polymers and the effect of aggregation on the device performance of conjugated polymer photovoltaic cells, new conjugated polymers (PVTT and CN-PVTT) having the same regioregularity but different intermolecular packing were prepared and characterized by means of UV-vis spectroscopy and atomic force microscopy (AFM). Photovoltaic devices were prepared with these polymers under different polymer-aggregate conditions. Polymer aggregation induced by thermal annealing increases the short circuit current but provides no advantage in the overall power conversion efficiency because of a decrease in the open circuit voltage. The device fabricated from a pre-aggregated polymer suspension, acquired from ultrasonic agitation of a conjugated polymer gel, showed enhanced performance because of better phase separation and reduced recombination between polymer/PCBM.

  18. Novel Effects of Compressed CO2 Molecules on Structural Ordering and Charge Transport in Conjugated Poly(3-hexylthiophene) Thin Films

    SciTech Connect

    Jiang, Naisheng; Sendogdular, Levent; Sen, Mani; Endoh, Maya K.; Koga, Tadanori; Fukuto, Masafumi; Akgun, Bulent; Satija, Sushil K.; Nam, Chang-Yong

    2016-10-06

    We report the effects of compressed CO2 molecules as a novel plasticization agent for poly(3- hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence Xray diffraction measurements after drying the films via rapid depressurization to atmospheric pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO2regardless of the type of polymers, the present findings suggest that the CO2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.tion films.

  19. Novel Effects of Compressed CO2 Molecules on Structural Ordering and Charge Transport in Conjugated Poly(3-hexylthiophene) Thin Films

    SciTech Connect

    Jiang, Naisheng; Sendogdular, Levent; Sen, Mani; Endoh, Maya K.; Koga, Tadanori; Fukuto, Masafumi; Akgun, Bulent; Satija, Sushil K.; Nam, Chang-Yong

    2016-10-06

    We report the effects of compressed CO2 molecules as a novel plasticization agent for poly(3- hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence Xray diffraction measurements after drying the films via rapid depressurization to atmospheric pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO2regardless of the type of polymers, the present findings suggest that the CO2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.tion films.

  20. Theoretical analysis of single molecule spectroscopy lineshapes of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Devi, Murali

    Conjugated Polymers(CPs) exhibit a wide range of highly tunable optical properties. Quantitative and detailed understanding of the nature of excitons responsible for such a rich optical behavior has significant implications for better utilization of CPs for more efficient plastic solar cells and other novel optoelectronic devices. In general, samples of CPs are plagued with substantial inhomogeneous broadening due to various sources of disorder. Single molecule emission spectroscopy (SMES) offers a unique opportunity to investigate the energetics and dynamics of excitons and their interactions with phonon modes. The major subject of the present thesis is to analyze and understand room temperature SMES lineshapes for a particular CP, called poly(2,5-di-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (DEH-PPV). A minimal quantum mechanical model of a two-level system coupled to a Brownian oscillator bath is utilized. The main objective is to identify the set of model parameters best fitting a SMES lineshape for each of about 200 samples of DEH-PPV, from which new insight into the nature of exciton-bath coupling can be gained. This project also entails developing a reliable computational methodology for quantum mechanical modeling of spectral lineshapes in general. Well-known optimization techniques such as gradient descent, genetic algorithms, and heuristic searches have been tested, employing an L2 measure between theoretical and experimental lineshapes for guiding the optimization. However, all of these tend to result in theoretical lineshapes qualitatively different from experimental ones. This is attributed to the ruggedness of the parameter space and inadequateness of the L2 measure. On the other hand, when the dynamic reduction of the original parameter space to a 2-parameter space through feature searching and visualization of the search space paths using directed acyclic graphs(DAGs), the qualitative nature of the fitting improved significantly. For a more

  1. Characterization of electrosynthesized conjugated polymer-carbon nanotube composite: optical nonlinearity and electrical property.

    PubMed

    Bahrami, Afarin; Talib, Zainal Abidin; Shahriari, Esmaeil; Yunus, Wan Mahmood Mat; Kasim, Anuar; Behzad, Kasra

    2012-01-01

    The effects of multi-walled carbon nanotube (MWNT) concentration on the structural, optical and electrical properties of conjugated polymer-carbon nanotube composite are discussed. Multi-walled carbon nanotube-polypyrrole nanocomposites were synthesized by electrochemical polymerization of monomers in the presence of different amounts of MWNTs using sodium dodecylbenzensulfonate (SDBS) as surfactant at room temperature and normal pressure. Field emission scanning electron microscopy (FESEM) indicates that the polymer is wrapped around the nanotubes. Measurement of the nonlinear refractive indices (n(2)) and the nonlinear absorption (β) of the samples with different MWNT concentrations measurements were performed by a single Z-scan method using continuous wave (CW) laser beam excitation wavelength of λ = 532 nm. The results show that both nonlinear optical parameters increased with increasing the concentration of MWNTs. The third order nonlinear susceptibilities were also calculated and found to follow the same trend as n(2) and β. In addition, the conductivity of the composite film was found to increase rapidly with the increase in the MWNT concentration.

  2. Characterization of Electrosynthesized Conjugated Polymer-Carbon Nanotube Composite: Optical Nonlinearity and Electrical Property

    PubMed Central

    Bahrami, Afarin; Talib, Zainal Abidin; Shahriari, Esmaeil; Yunus, Wan Mahmood Mat; Kasim, Anuar; Behzad, Kasra

    2012-01-01

    The effects of multi-walled carbon nanotube (MWNT) concentration on the structural, optical and electrical properties of conjugated polymer-carbon nanotube composite are discussed. Multi-walled carbon nanotube-polypyrrole nanocomposites were synthesized by electrochemical polymerization of monomers in the presence of different amounts of MWNTs using sodium dodecylbenzensulfonate (SDBS) as surfactant at room temperature and normal pressure. Field emission scanning electron microscopy (FESEM) indicates that the polymer is wrapped around the nanotubes. Measurement of the nonlinear refractive indices (n2) and the nonlinear absorption (β) of the samples with different MWNT concentrations measurements were performed by a single Z-scan method using continuous wave (CW) laser beam excitation wavelength of λ = 532 nm. The results show that both nonlinear optical parameters increased with increasing the concentration of MWNTs. The third order nonlinear susceptibilities were also calculated and found to follow the same trend as n2 and β. In addition, the conductivity of the composite film was found to increase rapidly with the increase in the MWNT concentration. PMID:22312294

  3. Dendritic polymer imaging systems for the evaluation of conjugate uptake and cleavage.

    PubMed

    Krüger, Harald R; Nagel, Gregor; Wedepohl, Stefanie; Calderón, Marcelo

    2015-03-07

    Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular release of cargo in a cell based microplate assay that is suitable for high throughput screening.

  4. Making waves in a photoactive polymer film

    NASA Astrophysics Data System (ADS)

    Gelebart, Anne Helene; Jan Mulder, Dirk; Varga, Michael; Konya, Andrew; Vantomme, Ghislaine; Meijer, E. W.; Selinger, Robin L. B.; Broer, Dirk J.

    2017-06-01

    Oscillating materials that adapt their shapes in response to external stimuli are of interest for emerging applications in medicine and robotics. For example, liquid-crystal networks can be programmed to undergo stimulus-induced deformations in various geometries, including in response to light. Azobenzene molecules are often incorporated into liquid-crystal polymer films to make them photoresponsive; however, in most cases only the bending responses of these films have been studied, and relaxation after photo-isomerization is rather slow. Modifying the core or adding substituents to the azobenzene moiety can lead to marked changes in photophysical and photochemical properties, providing an opportunity to circumvent the use of a complex set-up that involves multiple light sources, lenses or mirrors. Here, by incorporating azobenzene derivatives with fast cis-to-trans thermal relaxation into liquid-crystal networks, we generate photoactive polymer films that exhibit continuous, directional, macroscopic mechanical waves under constant light illumination, with a feedback loop that is driven by self-shadowing. We explain the mechanism of wave generation using a theoretical model and numerical simulations, which show good qualitative agreement with our experiments. We also demonstrate the potential application of our photoactive films in light-driven locomotion and self-cleaning surfaces, and anticipate further applications in fields such as photomechanical energy harvesting and miniaturized transport.

  5. Thermal gating in lipid membranes using thermoresponsive cyclic peptide-polymer conjugates.

    PubMed

    Danial, Maarten; Tran, Carmen M-N; Jolliffe, Katrina A; Perrier, Sébastien

    2014-06-04

    The partition and self-assembly of a new generation of cyclic peptide-polymer conjugates into well-defined phospholipid trans-bilayer channels is presented. By varying the structural parameters of the cyclic peptide-polymer conjugates through the ligation of hydrophobic and hydrophilic polymers, both the structure of the artificial channels using large unilamellar vesicle assays and the structural parameters required for phospholipid bilayer partitioning are elucidated. In addition, temperature was used as an external stimulus for the modulation of transbilayer channel formation without requiring the redesign and synthesis of the cyclic peptide core. The thermoresponsive character of the cyclic peptide-polymer conjugates lays the foundation for on-demand control over phospholipid transmembrane transport, which could lead to viable alternatives to current transport systems that traditionally rely on endocytic pathways.

  6. Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

    PubMed

    Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

    2016-06-01

    Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. DNA-SMART: Biopatterned Polymer Film Microchannels for Selective Immobilization of Proteins and Cells.

    PubMed

    Schneider, Ann-Kathrin; Nikolov, Pavel M; Giselbrecht, Stefan; Niemeyer, Christof M

    2017-02-22

    A novel SMART module, dubbed "DNA-SMART" (DNA substrate modification and replication by thermoforming) is reported, where polymer films are premodified with single-stranded DNA capture strands, microthermoformed into 3D structures, and postmodified with complementary DNA-protein conjugates to realize complex biologically active surfaces within microfluidic devices. As a proof of feasibility, it is demonstrated that microchannels presenting three different proteins on their inner curvilinear surface can be used for selective capture of cells under flow conditions.

  8. Synthesis of graphene-conjugated polymer nanocomposites for electronic device applications.

    PubMed

    Qi, Xiaoying; Tan, Chaoliang; Wei, Jun; Zhang, Hua

    2013-02-21

    Graphene-based polymer nanocomposites have attracted increasing interest because of their superior physicochemical properties over polymers. Semiconductor conjugated polymers (CPs) with excellent dispersibility and stability, and efficient electronic and optical properties have been recently integrated with graphene to form a new class of functional nanomaterials. In this minireview, we will summarize the recent advances in the development of graphene-CP nanocomposites for electronic device applications.

  9. Improving photo-stability of conjugated polymer MEH-PPV embedded in solid matrices by purification of the matrix polymer

    NASA Astrophysics Data System (ADS)

    Tian, Yuxi; Sheinin, Vladimir; Kulikova, Olga; Mamardashvili, Nugzar; Scheblykin, Ivan G.

    2014-04-01

    For single molecule spectroscopy (SMS), molecules under study are usually immobilized in a polymer matrix e.g. poly(methyl methacrylate). We show a very significant improvement of the conjugated polymer MEH-PPV photo-stability and decrease of the luminescence impurities concentration when the matrix is purified. We identify benzoyl peroxide (a common radical initiator) as a possible oxidizing agent which residuals in the polymer matrix destroy MEH-PPV. These results show that purification and selection of a matrix obtained by radical-free synthetic technique are of great importance for SMS as well as other technologies using polymer matrices as hosts for light-emitting materials.

  10. Direct Light-Driven Water Oxidation by a Ladder-Type Conjugated Polymer Photoanode

    PubMed Central

    2015-01-01

    A conjugated polymer known for high stability (poly[benzimidazobenzophenanthroline], coded as BBL) is examined as a photoanode for direct solar water oxidation. In aqueous electrolyte with a sacrificial hole acceptor (SO32–), photoelectrodes show a morphology-dependent performance. Films prepared by a dispersion-spray method with a nanostructured surface (feature size of ∼20 nm) gave photocurrents up to 0.23 ± 0.02 mA cm–2 at 1.23 VRHE under standard simulated solar illumination. Electrochemical impedance spectroscopy reveals a constant flat-band potential over a wide pH range at +0.31 VNHE. The solar water oxidation photocurrent with bare BBL electrodes is found to increase with increasing pH, and no evidence of semiconductor oxidation was observed over a 30 min testing time. Characterization of the photo-oxidation reaction suggests H2O2 or •OH production with the bare film, while functionalization of the interface with 1 nm of TiO2 followed by a nickel–cobalt catalyst gave solar photocurrents of 20–30 μA cm–2, corresponding with O2 evolution. Limitations to photocurrent production are discussed. PMID:26576469

  11. Developing conjugated polymers with high electron affinity by replacing a C-C unit with a B←N unit.

    PubMed

    Dou, Chuandong; Ding, Zicheng; Zhang, Zijian; Xie, Zhiyuan; Liu, Jun; Wang, Lixiang

    2015-03-16

    The key parameters of conjugated polymers are lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels. Few approaches can simultaneously lower LUMO and HOMO energy levels of conjugated polymers to a large extent (>0.5 eV). Disclosed herein is a novel strategy to decrease both LUMO and HOMO energy levels of conjugated polymers by about 0.6 eV through replacement of a C-C unit by a B←N unit. The replacement makes the resulting polymer transform from an electron donor into an electron acceptor, and is proven by fluorescence quenching experiments and the photovoltaic response. This work not only provides an effective approach to tune the LUMO/HOMO energy levels of conjugated polymers, but also uses organic boron chemistry as a new toolbox to develop conjugated polymers with high electron affinity for polymer optoelectronic devices.

  12. Interplay of localized pyrene chromophores and π-conjugation in novel poly(2,7-pyrene) ladder polymers

    NASA Astrophysics Data System (ADS)

    Rudnick, Alexander; Kass, Kim-Julia; Preis, Eduard; Scherf, Ullrich; Bässler, Heinz; Köhler, Anna

    2017-05-01

    We present a detailed spectroscopic study, along with the synthesis, of conjugated, ladder-type 2,7-linked poly(pyrene)s. We observe a delocalization of the first singlet excited state along the polymer backbone, i.e., across the 2,7 linkage in the pyrene moiety, in contrast to earlier studies on conjugated 2,7-linked poly(pyrene)s without ladder structure. The electronic signature of the pyrene unit is, however, manifested in an increased lifetime and reduced oscillator strength as well as a modified vibronic progression in absorption of the singlet state compared to a ladder-type poly(para-phenylene) (MeLPPP). Furthermore, the reduced oscillator strength and increased lifetime slow down Förster-type energy transfer in films, where this transfer occurs to sites with increasing inter-chain coupling of H-type nature.

  13. Unusual doping of donor-acceptor-type conjugated polymers using lewis acids.

    PubMed

    Poverenov, Elena; Zamoshchik, Natalia; Patra, Asit; Ridelman, Yonatan; Bendikov, Michael

    2014-04-02

    Conjugated polymers that can undergo unusual nonoxidative doping were designed. A series of polymers based on donor-acceptor-donor (DAD) moieties 2,1,3-benzoselenadiazole, 2,1,3-benzothiadiazole, 2,1,3-benzoxadiazolebenzo[2,1,5]oxodiazole, and 2-hexylbenzotriazole as acceptor fragments and 3,4-ethylenedioxyselenophene (EDOS) and 3,4-ethylenedioxythiophene (EDOT) as donor fragments was prepared. When the studied polymers were reacted with Lewis acids and bases, notable optical switching and conductivity changes were observed, evidencing the exceptional case of efficient nonoxidative doping/dedoping. Remarkably, in previously reported works, coordination of Lewis acids causes band gap shift but not doping of the conductive polymer, while in the present study, coordination of Lewis acid to highly donating EDOT and EDOS moieties led to polymer doping. The polymers show remarkable stability after numerous switching cycles from neutral to doped states and vice versa and can be switched both electrochemically and chemically. The reactivity of the prepared polymers with Lewis acids and bases of different strengths was studied. Calculation studies of the Lewis acid coordination mode, its effect on polymer energies and band gap, support the unusual doping. The reported doping approach opens up the possibility to control the conjugation, color change, and switching of states of conjugated polymers without oxidation.

  14. π-Conjugated polymer anisotropic organogel nanofibrous assemblies for thermoresponsive photonic switches.

    PubMed

    Narasimha, Karnati; Jayakannan, Manickam

    2014-11-12

    The present work demonstrates one of the first examples of π-conjugated photonic switches (or photonic wave plates) based on the tailor-made π-conjugated polymer anisotropic organogel. New semicrystalline segmented π-conjugated polymers are designed with rigid aromatic oligophenylenevinylene π-core and flexible alkyl chain along the polymer backbone. These polymers are found to be self-assembled as semicrystalline or amorphous with respect to the number of carbon atoms in the alkyl units. These semicrystalline polymers produce organogels having nanofibrous morphology of 20 nm thickness with length up to 5 μm. The polymer organogel is aligned in a narrow glass capillary, and this anisotropic gel device is further demonstrated as photonic switches. The glass capillary device behaves as typical λ/4 photonic wave plates upon the illumination of the plane polarized light. The λ/4 photonic switching ability is found to be maximum at θ = 45° angle under the cross polarizers. The orthogonal arrangements of the gel capillaries produce dark and bright spots as on-and-off optical switches. Thermoreversibility of the polymer organogel (also its xerogel) was exploited to construct thermoresponsive photonic switches for the temperature window starting from 25 to 160 °C. The organic photonic switch concept can be adapted to large number of other π-conjugated materials for optical communication and storage.

  15. Exciton diffusion and dissociation in conjugated polymer/fullerene blends and heterostructures

    NASA Astrophysics Data System (ADS)

    Haugeneder, A.; Neges, M.; Kallinger, C.; Spirkl, W.; Lemmer, U.; Feldmann, J.; Scherf, U.; Harth, E.; Gügel, A.; Müllen, K.

    1999-06-01

    We investigate the exciton dynamics in composite systems of conjugated polymers and fullerene molecules by photoluminescence (PL) and femtosecond transient absorption experiments. In solid mixtures (blends) we find a strong concentration-dependent quenching of the polymer PL. This is attributed to an efficient electron transfer (ET) from the photoexcited conjugated polymer to the fullerene. The ET dynamics is directly monitored by measuring the transient stimulated emission of the conjugated polymer. The transfer rate depends linearly on the C60 concentration and ranges between (66 ps)-1 and (5 ps)-1 for concentrations from 0.5% to 5%. This dependence is in accordance with an exciton diffusion process occurring prior to the ET. The exciton diffusion length in the conjugated polymer is directly determined by measuring the PL quenching in well-defined heterostructures comprising a self-assembled fullerene monolayer and a thin spin-coated polymer layer of variable thickness. From these measurements we infer a value of 14 nm for the exciton diffusion length in ladder-type poly (p-phenylene). Our results are of direct relevance for further optimization of polymer photovoltaic devices.

  16. Influence of backbone rigidness on single chain conformation of thiophene-based conjugated polymers.

    PubMed

    Hu, Zhongjian; Liu, Jianhua; Simón-Bower, Lauren; Zhai, Lei; Gesquiere, Andre J

    2013-04-25

    Structural order of conjugated polymers at different length scales directs the optoelectronic properties of the corresponding materials; thus it is of critical importance to understand and control conjugated polymer morphology for successful application of these materials in organic optoelectronics. Herein, with the aim of probing the dependence of single chain folding properties on the chemical structure and rigidness of the polymer backbones, single molecule fluorescence spectroscopy was applied to four thiophene-based conjugated polymers. These include regioregular poly(3-hexylthiophene) (RR-P3HT), poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-14), poly(2,5-bis(3-tetradecylthiophen-2-yl)thiophene-2-yl)thiophen-2-ylthiazolo[5,4-d]thiazole) (PTzQT-12), and poly(3,3-didodecylquaterthiophene)] (PQT-12). Our previous work has shown that RR-P3HT and PBTTT-14 polymer chains fold in their nanostructures, whereas PQT-12 and PTzQT-12 do not fold in their nanostructures. At the single molecule level, it was found that RR-P3HT single chains almost exclusively fold into loosely and strongly aggregated conformations, analogous to the folding properties in nanostructures. PQT-12 displays significant chain folding as well, but only into loosely aggregated conformations, showing an absence of strongly aggregated polymer chains. PBTTT-14 exhibits a significant fraction of rigid polymer chain. The findings made for single molecules of PQT-12 and PBTTT-14 are thus in contrast with the observations made in their corresponding nanostructures. PTzQT-12 appears to be the most rigid and planar conjugated polymer of these four polymers. However, although the presumably nonfolding polymers PQT-12 and PTzQT-12 exhibit less folding than RR-P3HT, there is still a significant occurrence of chain folding for these polymers at the single molecule level. These results suggest that the folding properties of conjugated polymers can be influenced by the architecture of the

  17. Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

    NASA Astrophysics Data System (ADS)

    Shu, Jessica Yo

    The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly

  18. Pluronic-lysozyme conjugates as anti-adhesive and antibacterial bifunctional polymers for surface coating.

    PubMed

    Muszanska, Agnieszka K; Busscher, Henk J; Herrmann, Andreas; van der Mei, Henny C; Norde, Willem

    2011-09-01

    This paper describes the preparation and characterization of polymer-protein conjugates composed of a synthetic triblock copolymer with a central polypropylene oxide (PPO) block and two terminal polyethylene oxide (PEO) segments, Pluronic F-127, and the antibacterial enzyme lysozyme attached to the telechelic groups of the PEO chains. Covalent conjugation of lysozyme proceeded via reductive amination of aldehyde functionalized PEO blocks (CHO-Pluronic) and the amine groups of the lysine residues in the protein. SDS-PAGE gel electrophoresis together with MALDI-TOF mass spectrometry analysis revealed formation of conjugates of one or two lysozyme molecules per Pluronic polymer chain. The conjugated lysozyme showed antibacterial activity towards Bacillus subtilis. Analysis with a quartz crystal microbalance with dissipation revealed that Pluronic-lysozyme conjugates adsorb in a brush conformation on a hydrophobic gold-coated quartz surface. X-ray photoelectron spectroscopy indicated surface coverage of 32% by lysozyme when adsorbed from a mixture of unconjugated Pluronic and Pluronic-lysozyme conjugate (ratio 99:1) and of 47% after adsorption of 100% Pluronic-lysozyme conjugates. Thus, bifunctional brushes were created, possessing both anti-adhesive activity due to the polymer brush, combined with the antibacterial activity of lysozyme. The coating having a lower degree of lysozyme coverage proved to be more bactericidal.

  19. Protein polymer conjugates: improving the stability of hemoglobin with poly(acrylic acid).

    PubMed

    Thilakarathne, Vindya; Briand, Victoria A; Zhou, Yuxiang; Kasi, Rajeswari M; Kumar, Challa V

    2011-06-21

    The synthesis, characterization, and evaluation of a novel polymer-protein conjugate are reported here. The covalent conjugation of high-molecular weight poly(acrylic acid) (PAA) to the lysine amino groups of met-hemoglobin (Hb) resulted in the covalent conjugation of Hb to PAA (Hb-PAA conjugate), as confirmed by dialysis and electrophoresis studies. The retention of native-like structure of Hb in Hb-PAA was established from Soret absorption, circular dichroism studies, and the redox activity of the iron center in Hb-PAA. The peroxidase-like activities of the Hb-PAA conjugate further confirmed the retention of Hb structure and biological activity. Thermal denaturation of the conjugate was investigated by differential scanning calorimetry and steam sterilization studies. The Hb-PAA conjugate indicated an improved denaturation temperature (T(d)) when compared to that of the unmodified Hb. One astonishing observation was that polymer conjugation significantly enhanced the Hb-PAA storage stability at room temperature. After 120 h of storage at room temperature in phosphate-buffered saline (PBS) at pH 7.4, for example, Hb-PAA retained 90% of its initial activity and unmodified Hb retained <60% of its original activity under identical conditions of buffer, pH, and temperature. Our conjugate demonstrates the key role of polymers in enhancing Hb stability via a very simple, efficient, general route. Water-swollen, lightly cross-linked, stable Hb-polymer nanogels of 100-200 nm were produced quickly and economically by this approach for a wide variety of applications.

  20. Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells.

    PubMed

    Xie, Jian; Zhao, Cui-E; Lin, Zong-Qiong; Gu, Pei-Yang; Zhang, Qichun

    2016-05-20

    To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Preparation of Gemini Surfactant/Conjugated Polymer Aggregates for Enhanced Fluorescence and Bioimaging Application.

    PubMed

    Wang, Hua; Zhou, Lingyun; Zhou, Chengcheng; Zhao, Weiwei; Wang, Jianwu; Liu, Libing; Wang, Shu; Wang, Yilin

    2017-07-19

    Conjugated polymers have great potential applications in bioimaging. However, the aggregation of conjugated polymers driven by electrostatic and hydrophobic interactions in aqueous media results in the reduction of photoluminescence quantum efficiency. In present work we synthesized a carboxylate gemini surfactant [sodium 2,6-didodecyl-4-hydroxy-2,6-diaza-1,7-heptanedicarboxylate (SDHC)] to adjust the aggregation behaviors and fluorescence properties of conjugated polymers [anionic poly(2-methoxy-5-propyloxy sulfonate phenylene vinylene) (MPS-PPV) and cationic poly(3-alkoxy-4-methylthiophene) (PMNT)]. This gemini surfactant shows very low critical micellar concentration (CMC) in aqueous solution and forms vesicles above CMC. In neutral and acidic conditions, MPS-PPV combines with the SDHC vesicles mainly via hydrophobic interactions and forms the aggregates in which the photoluminescence quantum efficiency of MPS-PPV is highly enhanced from 0.1% to 27%. As to PMNT, the molecules are located in the bilayer of SDHC vesicles through both electrostatic and hydrophobic interactions, and this structure prevents the production and release of reactive oxygen species. Moreover, SDHC is nontoxic and can effectively decrease the dark- and photocytotoxicity of MPS-PPV and PMNT, laying a good foundation for their bioimaging application. The living cell imaging indicates that the surfactant/conjugated polymer aggregates can stain the MCF-7 cells with main location in the lysosome. This work provides insight into how to improve the fluorescence properties and bioimaging applications of conjugated polymers by surfactants.

  2. A Porphyrin-Based Conjugated Polymer for Highly Efficient In Vitro and In Vivo Photothermal Therapy.

    PubMed

    Guo, Bing; Feng, Guangxue; Manghnani, Purnima Naresh; Cai, Xiaolei; Liu, Jie; Wu, Wenbo; Xu, Shidang; Cheng, Xiamin; Teh, Cathleen; Liu, Bin

    2016-12-01

    Conjugated polymers have been increasingly studied for photothermal therapy (PTT) because of their merits including large absorption coefficient, facile tuning of exciton energy dissipation through nonradiative decay, and good therapeutic efficacy. The high photothermal conversion efficiency (PCE) is the key to realize efficient PTT. Herein, a donor-acceptor (D-A) structured porphyrin-containing conjugated polymer (PorCP) is reported for efficient PTT in vitro and in vivo. The D-A structure introduces intramolecular charge transfer along the backbone, resulting in redshifted Q band, broadened absorption, and increased extinction coefficient as compared to the state-of-art porphyrin-based photothermal reagent. Through nanoencapsulation, the dense packing of a large number of PorCP molecules in a single nanoparticle (NP) leads to favorable nonradiative decay, good photostability, and high extinction coefficient of 4.23 × 10(4) m(-1) cm(-1) at 800 nm based on porphyrin molar concentration and the highest PCE of 63.8% among conjugated polymer NPs. With the aid of coloaded fluorescent conjugated polymer, the cellular uptake and distribution of the PorCP in vitro can be clearly visualized, which also shows effective photothermal tumor ablation in vitro and in vivo. This research indicates a new design route of conjugated polymer-based photothermal therapeutic materials for potential personalized theranostic nanomedicine.

  3. The pH-dependent and enzymatic release of cytarabine from hydrophilic polymer conjugates.

    PubMed

    Pola, R; Janoušková, O; Etrych, T

    2016-10-20

    Cytarabine is one of the most efficient drugs in the treatment of hematological malignancies. In this work, we describe the synthesis and characterization of two different polymer conjugates of cytarabine that were designed for the controlled release of cytarabine within the leukemia cells. Reactive copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) and 3-(3-methacrylamidopropa-noyl)thiazolidine-2-thione) or 3-(Nmethacryloylglycyl-phenylalanylleucylglycyl)thiazolidine-2-thione were used in the study as reactive polymer precursors for reaction with cytarabine. The enzymatic release of cytarabine from the conjugate containing a GFLG spacer utilizing cathepsin B was verified. In addition to enzymolysis, the pH-dependent hydrolysis of cytarabine from both copolymers was also confirmed. Approximately 40 % and 20 % of the drug was released by spontaneous hydrolysis at pH 7.4 within 72 h from the polymer conjugates with the GFLG and beta-Ala spacers, respectively. At pH 6.0, the spontaneous hydrolysis slowed down, and less than 10 % of the drug was liberated within 72 h. The results of the cytotoxicity evaluation of the polymer conjugates in vitro against various cell lines showed that the cytotoxicity of the polymer conjugates is approximately three times lower in comparison to free cytarabine.

  4. Understanding the relationship between molecular order and charge transport properties in conjugated polymer based organic blend photovoltaic devices.

    PubMed

    Wood, Sebastian; Kim, Jong Soo; James, David T; Tsoi, Wing C; Murphy, Craig E; Kim, Ji-Seon

    2013-08-14

    We report a detailed characterization of the thin film morphology of all-polymer blend devices by applying a combined analysis of physical, chemical, optical, and charge transport properties. This is exemplified by considering a model system comprising poly(3-hexylthiophene) (P3HT) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). We show that the interactions between the two conjugated polymer components can be controlled by pre-forming the P3HT into highly ordered nanowire structures prior to blending with F8BT, and by varying the molecular weight of the F8BT. As a result, it is possible to produce films containing highly ordered P3HT with hole mobilities enhanced by three orders of magnitude over the pristine blends. Raman spectroscopy under resonant excitation conditions is used to probe the molecular order of both P3HT and F8BT phases within the blend films and these morphological studies are complemented by measurements of photocurrent generation. The resultant increase in photocurrent is associated with the enhanced charge carrier mobilities. The complementary analytical method demonstrated here is applicable to a wide range of polymer blend systems for all applications where the relationships between morphology and device performance are of interest.

  5. Scanning Tunneling Microscopy analysis of space-exposed polymer films

    NASA Technical Reports Server (NTRS)

    Kalil, Carol R.; Young, Philip R.

    1993-01-01

    The characterization of the surface of selected space-exposed polymer films by Scanning Tunneling Microscopy (STM) is reported. Principles of STM, an emerging new technique for materials analysis, are reviewed. The analysis of several films which received up to 5.8 years of low Earth orbital (LEO) exposure onboard the NASA Long Duration Exposure Facility (LDEF) is discussed. Specimens included FEP Teflon thermal blanket material, Kapton film, and several experimental polymer films. Ultraviolet and atomic oxygen-induced crazing and erosion are described. The intent of this paper is to demonstrate how STM is enhancing the understanding of LEO space environmental effects on polymer films.

  6. Conjugated polymers containing diketopyrrolopyrrole units in the main chain

    PubMed Central

    Rabindranath, A Raman; Zhang, Kai; Zhu, Yu

    2010-01-01

    Summary Research activities in the field of diketopyrrolopyrrole (DPP)-based polymers are reviewed. Synthetic pathways to monomers and polymers, and the characteristic properties of the polymers are described. Potential applications in the field of organic electronic materials such as light emitting diodes, organic solar cells and organic field effect transistors are discussed. PMID:20978619

  7. Capture and conversion of CO2 at ambient conditions by a conjugated microporous polymer

    PubMed Central

    Xie, Yong; Wang, Ting-Ting; Liu, Xiao-Huan; Zou, Kun; Deng, Wei-Qiao

    2013-01-01

    Conjugated microporous polymers are a new class of porous materials with an extended π-conjugation in an amorphous organic framework. Owing to the wide-ranging flexibility in the choice and design of components and the available control of pore parameters, these polymers can be tailored for use in various applications, such as gas storage, electronics and catalysis. Here we report a class of cobalt/aluminium-coordinated conjugated microporous polymers that exhibit outstanding CO2 capture and conversion performance at atmospheric pressure and room temperature. These polymers can store CO2 with adsorption capacities comparable to metal-organic frameworks. The cobalt-coordinated conjugated microporous polymers can also simultaneously function as heterogeneous catalysts for the reaction of CO2 and propylene oxide at atmospheric pressure and room temperature, wherein the polymers demonstrate better efficiency than a homogeneous salen-cobalt catalyst. By combining the functions of gas storage and catalysts, this strategy provides a direction for cost-effective CO2 reduction processes. PMID:23727768

  8. Conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis.

    PubMed

    Su, Yu-Wei; Lin, Wei-Hao; Hsu, Yung-Jung; Wei, Kung-Hwa

    2014-11-01

    Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed.

  9. Remarkable enhancement of charge carrier mobility of conjugated polymer field-effect transistors upon incorporating an ionic additive.

    PubMed

    Luo, Hewei; Yu, Chenmin; Liu, Zitong; Zhang, Guanxin; Geng, Hua; Yi, Yuanping; Broch, Katharina; Hu, Yuanyuan; Sadhanala, Aditya; Jiang, Lang; Qi, Penglin; Cai, Zhengxu; Sirringhaus, Henning; Zhang, Deqing

    2016-05-01

    Organic semiconductors with high charge carrier mobilities are crucial for flexible electronic applications. Apart from designing new conjugated frameworks, different strategies have been explored to increase charge carrier mobilities. We report a new and simple approach to enhancing the charge carrier mobility of DPP-thieno[3,2-b]thiophene-conjugated polymer by incorporating an ionic additive, tetramethylammonium iodide, without extra treatments into the polymer. The resulting thin films exhibit a very high hole mobility, which is higher by a factor of 24 than that of thin films without the ionic additive under the same conditions. On the basis of spectroscopic grazing incidence wide-angle x-ray scattering and atomic force microscopy studies as well as theoretical calculations, the remarkable enhancement of charge mobility upon addition of tetramethylammonium iodide is attributed primarily to an inhibition of the torsion of the alkyl side chains by the presence of the ionic species, facilitating a more ordered lamellar packing of the alkyl side chains and interchain π-π interactions.

  10. Remarkable enhancement of charge carrier mobility of conjugated polymer field-effect transistors upon incorporating an ionic additive

    PubMed Central

    Luo, Hewei; Yu, Chenmin; Liu, Zitong; Zhang, Guanxin; Geng, Hua; Yi, Yuanping; Broch, Katharina; Hu, Yuanyuan; Sadhanala, Aditya; Jiang, Lang; Qi, Penglin; Cai, Zhengxu; Sirringhaus, Henning; Zhang, Deqing

    2016-01-01

    Organic semiconductors with high charge carrier mobilities are crucial for flexible electronic applications. Apart from designing new conjugated frameworks, different strategies have been explored to increase charge carrier mobilities. We report a new and simple approach to enhancing the charge carrier mobility of DPP-thieno[3,2-b]thiophene–conjugated polymer by incorporating an ionic additive, tetramethylammonium iodide, without extra treatments into the polymer. The resulting thin films exhibit a very high hole mobility, which is higher by a factor of 24 than that of thin films without the ionic additive under the same conditions. On the basis of spectroscopic grazing incidence wide-angle x-ray scattering and atomic force microscopy studies as well as theoretical calculations, the remarkable enhancement of charge mobility upon addition of tetramethylammonium iodide is attributed primarily to an inhibition of the torsion of the alkyl side chains by the presence of the ionic species, facilitating a more ordered lamellar packing of the alkyl side chains and interchain π-π interactions. PMID:27386541

  11. Nanoscale imaging of nonequilibrium polymer films

    NASA Astrophysics Data System (ADS)

    King, John; Granick, Steve

    2015-03-01

    In recent years there have been exciting advances in sub-diffraction limited imaging based on fluorescence microscopy. While most applications of super-resolution microscopy focus on static biological imaging, we are interested in extending these techniques to the study of polymer dynamics. To this end, we couple stimulated emission depletion (STED) with spectroscopic detection, relying on spectral features of fluorescence emission to serve as the imaging contrast agent. We aim to adapt fluorescent dyes responsive to environmental properties (polarity, mobility, current, temperature, ect.) to STED imaging. Using the fluorescent spectral response as a contrast agent allows for nanoscopic environments to be directly imaged without the need for specific labeling. Rapid acquisition of images allows for slow dynamic processes in nonequilibrium polymer films to be imaged in real time. We demonstrate the power of super-resolution spectroscopic imaging by directly imaging several topical problems in materials science.

  12. Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

    PubMed

    Stahl, Thomas; Bofinger, Robin; Lam, Ivan; Fallon, Kealan J; Johnson, Peter; Ogunlade, Olumide; Vassileva, Vessela; Pedley, R Barbara; Beard, Paul C; Hailes, Helen C; Bronstein, Hugo; Tabor, Alethea B

    2017-06-21

    Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo.

  13. Beyond superquenching: Hyper-efficient energy transfer from conjugated polymers to gold nanoparticles

    PubMed Central

    Fan, Chunhai; Wang, Shu; Hong, Janice W.; Bazan, Guillermo C.; Plaxco, Kevin W.; Heeger, Alan J.

    2003-01-01

    Gold nanoparticles quench the fluorescence of cationic polyfluorene with Stern–Volmer constants (KSV) approaching 1011 M—1, several orders of magnitude larger than any previously reported conjugated polymer–quencher pair and 9–10 orders of magnitude larger than small molecule dye–quencher pairs. The dependence of KSV on ionic strength, charge and conjugation length of the polymer, and the dimensions (and thus optical properties) of the nanoparticles suggests that three factors account for this extraordinary efficiency: (i) amplification of the quenching via rapid internal energy or electron transfer, (ii) electrostatic interactions between the cationic polymer and anionic nanoparticles, and (iii) the ability of gold nanoparticles to quench via efficient energy transfer. As a result of this extraordinarily high KSV, quenching can be observed even at subpicomolar concentrations of nanoparticles, suggesting that the combination of conjugated polymers with these nanomaterials can potentially lead to improved sensitivity in optical biosensors. PMID:12750470

  14. Realization of large area flexible fullerene-conjugated polymer photocells: A route to plastic solar cells

    NASA Astrophysics Data System (ADS)

    Brabec, C. J.; Padinger, F.; Dyakonov, V.; Hummelen, J. C.; Janssen, R. A. J.; Sariciftci, N. S.

    1998-08-01

    Various interesting photophysical phenomena in composites of fullerenes and non degenerate ground state conjugated polymers with highly extended π-electrons in their main chain can be explained by the ultrafast electron transfer from the conjugated polymer (donor) to the fullerene (acceptor) upon illumination. This photoeffect was utilized for the production of small area (mm2) photovoltaic devices which show energy conversion efficiencies ηe>1% and carrier collection efficiencies ηc>20%. In this work we present efficiency and stability studies on large area (6 cm by 6 cm) flexible solar cells based on a soluble alkoxy PPV (3,7-dimethyloctyloxy methyloxy poly(phenylenevinylene)) and a highly soluble fullerene derivative, 1-(3-methoxycarbonyl)propyl-1 phenyl [5,6]C61 (PCBM). The enhanced solubility of PCBM compared to C60 allows a high fullerene-conjugated polymer ratio and strongly supports the formation of donor-acceptor bulk heterojunctions.

  15. Silicon oxide colloidal/polymer nanocomposite films

    SciTech Connect

    Wang Haifeng; Cao Wenwu; Zhou, Q.F.; Shung, K. Kirk; Huang, Y.H.

    2004-12-13

    The quarter-wavelength ({lambda}/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50 MHz), the {lambda}/4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  16. Silicon oxide colloidal/polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Wang, Haifeng; Cao, Wenwu; Zhou, Q. F.; Shung, K. Kirk; Huang, Y. H.

    2004-12-01

    The quarter-wavelength (λ/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50MHz), the λ /4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  17. Gate-induced superconductivity in a solution-processed organic polymer film

    NASA Astrophysics Data System (ADS)

    Schön, J. H.; Dodabalapur, A.; Bao, Z.; Kloc, Ch.; Schenker, O.; Batlogg, B.

    2001-03-01

    The electrical and optical properties of conjugated polymers have received considerable attention in the context of potentially low-cost replacements for conventional metals and inorganic semiconductors. Charge transport in these organic materials has been characterized in both the doped-metallic and the semiconducting state, but superconductivity has not hitherto been observed in these polymers. Here we report a distinct metal-insulator transition and metallic levels of conductivity in a polymer field-effect transistor. The active material is solution-cast regioregular poly(3-hexylthiophene), which forms relatively well ordered films owing to self-organization, and which yields a high charge carrier mobility (0.05-0.1cm2V-1s-1) at room temperature. At temperatures below ~2.35K with sheet carrier densities exceeding 2.5 × 1014cm-2, the polythiophene film becomes superconducting. The appearance of superconductivity seems to be closely related to the self-assembly properties of the polymer, as the introduction of additional disorder is found to suppress superconductivity. Our findings therefore demonstrate the feasibility of tuning the electrical properties of conjugated polymers over the largest range possible-from insulating to superconducting.

  18. Polymer compositions, polymer films and methods and precursors for forming same

    DOEpatents

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  19. Near-infrared (NIR) emitting conjugated polymers for biomedical applications (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Repenko, Tatjana; Kuehne, Alexander J. C.

    2015-10-01

    Fluorescent biomedical markers of today such as dye-infiltrated colloids, microgels and quantum dots suffer from fast bleaching, lack surface functionality (for targets or pharmaceutical agents) and potentially leach heavy metals in case of quantum dots (e.g. Cd). By contrast, conjugated polymer particles are non-cytotoxic, exhibit reduced bleaching, as the entire particle consists of fluorophore, they are hydrophobic and show high quantum yields. Consequently, conjugated polymer particles represent ideal materials for biological applications and imaging. However currently, conjugated polymer particles for biomedical imaging usually lack near-infrared (NIR) emission and are polydisperse. Fluorescent agents with emission in the NIR spectrum are interesting for biomedical applications due to their low photo-damage towards biological species and the ability of NIR radiation to penetrate deep into biological tissue.. I will present the development and synthesis of new conjugated polymers particles with fluorescence in the NIR spectral region for bio-imaging and clinical diagnosis. The particle synthesis proceeds in a one-step Pd or Ni-catalyzed dispersion polymerization of functional NIR emitters. The resulting monodisperse conjugated polymer particles are obtained as a dispersion in a non-hazardous solvent. Different sizes in the sub-micrometer range with a narrow size distribution can be produced. Furthermore biological recognition motifs can be easily attached to the conjugated polymers via thiol-yne click-chemistry providing specific tumor targeting without quenching of the fluorescence. References [1] Kuehne AJC, Gather MC, Sprakel J., Nature Commun. 2012, 3, 1088. [2] Repenko T, Fokong S, De Laporte L, Go D, Kiessling F, Lammers T, Kuehne AJC.,Chem Commun 2015, accepted.

  20. Second and third order nonlinear optical properties of conjugated molecules and polymers

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Stiegman, Albert E.; Marder, Seth R.; Coulter, Daniel R.; Beratan, David N.; Brinza, David E.

    1988-01-01

    Second- and third-order nonlinear optical properties of some newly synthesized organic molecules and polymers are reported. Powder second-harmonic-generation efficiencies of up to 200 times urea have been realized for asymmetric donor-acceptor acetylenes. Third harmonic generation chi(3)s have been determined for a series of small conjugated molecules in solution. THG chi(3)s have also been determined for a series of soluble conjugated copolymers prepared using ring-opening metathesis polymerization. The results are discussed in terms of relevant molecular and/or macroscopic structural features of these conjugated organic materials.

  1. Drug conjugation to cyclic peptide-polymer self-assembling nanotubes.

    PubMed

    Blunden, Bianca M; Chapman, Robert; Danial, Maarten; Lu, Hongxu; Jolliffe, Katrina A; Perrier, Sébastien; Stenzel, Martina H

    2014-09-26

    We show for the first time how polymeric nanotubes (NTs) based on self-assembled conjugates of polymers and cyclic peptides can be used as an efficient drug carrier. RAPTA-C, a ruthenium-based anticancer drug, was conjugated to a statistical co-polymer based on poly(2-hydroxyethyl acrylate) (pHEA) and poly(2-chloroethyl methacrylate) (pCEMA), which formed the shell of the NTs. Self-assembly into nanotubes (length 200-500 nm) led to structures exhibiting high activity against cancer cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Hybrid nanostructures using pi-conjugated polymers and nanoscale metals: synthesis, characteristics, and optoelectronic applications.

    PubMed

    Park, Dong Hyuk; Kim, Mi Suk; Joo, Jinsoo

    2010-07-01

    Pi-conjugated organic systems have been used as optoelectronic and sensing materials due to their characteristics of efficient light emission or absorption, and p-type charge transport. The hybrid nanostructures of pi-conjugated organic systems with nanoscale metals offer surface plasmon (SP)-enhanced luminescence, which can be applied to organic-based optoelectronics, photonics, and sensing. Various hybrid nanostructures using light-emitting polymers with nanoscale metals have been fabricated and have shown considerable enhancement of photoluminescence efficiency due to energy and charge transfer effects in SP resonance coupling. In this tutorial review, recent conceptual and technological achievements in light-emitting polymers-based hybrid nanostructures are described.

  3. High-sensitivity DNA biosensor based on optical fiber taper interferometer coated with conjugated polymer tentacle.

    PubMed

    Huang, Yunyun; Tian, Zhuang; Sun, Li-Peng; Sun, Dandan; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2015-10-19

    A sensitive bio-probe to in situ detect unlabeled single-stranded DNA targets based on optical microfiber taper interferometer coated by a high ordered pore arrays conjugated polymer has been presented. The polymer coating serves as tentacles to catch single-stranded DNA molecules by π-π conjugated interaction and varies the surface refractive index of the optical microfiber. The microfiber taper interferometer translates the refractive index information into wavelength shift of the interference fringe. The sensor exhibits DNA concentration sensitivity of 2.393 nm/log M and the lowest detection ability of 10(-10) M or even lower.

  4. Hot Hole Transfer Increasing Polaron Yields in Hybrid Conjugated Polymer/PbS Blends.

    PubMed

    Strein, Elisabeth; deQuilettes, Dane W; Hsieh, Stephen T; Colbert, Adam E; Ginger, David S

    2014-01-02

    We use quasi-steady-state photoinduced absorption (PIA) to study charge generation in blends of poly(3-hexylthiophene-2,5-diyl) (P3HT) with PbS nanocrystal quantum dots as a function of excitation energy. We find that, per photon absorbed, the yield of photogenerated holes present on the conjugated polymer increases with pump energy, even at wavelengths where only the quantum dots absorb. We interpret this result as direct evidence for transfer of hot holes in these conjugated polymer/quantum dot blends. These results help understand the operation of hybrid organic/inorganic photovoltaics.

  5. The Role of Morphology and Electronic Chain Aggregation on the Optical Gain Properties of Semiconducting Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Lampert, Zachary Evan

    Conjugated polymers (CPs) are a novel class of materials that exhibit the optical and electrical properties of semiconductors while still retaining the durability and processability of plastics. CPs are also intrinsically 4-level systems with high luminescence quantum efficiencies making them particularly attractive as organic gain media for solid-state laser applications. However, before CPs can emerge as a commercially available laser technology, a more comprehensive understanding of the morphological dependence of the photophysics is required. In this thesis, the morphology and chain conformation dependence of amplified spontaneous emission (ASE) and optical gain in thin films of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) was investigated. By changing the chemical nature of the solvent from which films were cast, as well as the temperature at which films were annealed, CP films with different morphologies, and hence different degrees of interchain interactions were achieved. Contrary to the common perception that polymer morphology plays a decisive role in determining the ASE behavior of thin CP films, we found that chromophore aggregation and degree of conformational order have minimal impact on optical gain. In fact, experimental results indicated that an extremely large fraction of interchain aggregate species and/or exciton dissociating defects are required to significantly alter the optical properties and suppress stimulated emission. These results are pertinent to the fabrication and optimization of an electrically pumped laser device, as improvements in charge carrier mobility through controlled increases in chain aggregation may provide a viable means of optimizing injection efficiency without significantly degrading optical gain. To offset charge-induced absorption losses under electrical pumping, and to enable the use of more compact and economical sources under optical pumping, conjugated polymers exhibiting low lasing

  6. Flexible Polymer/Metal/Polymer and Polymer/Metal/Inorganic Trilayer Transparent Conducting Thin Film Heaters with Highly Hydrophobic Surface.

    PubMed

    Kang, Tae-Woon; Kim, Sung Hyun; Kim, Cheol Hwan; Lee, Sang-Mok; Kim, Han-Ki; Park, Jae Seong; Lee, Jae Heung; Yang, Yong Suk; Lee, Sang-Jin

    2017-09-27

    Polymer/metal/polymer and polymer/metal/inorganic trilayer-structured transparent electrodes with fluorocarbon plasma polymer thin film heaters have been proposed. The polymer/metal/polymer and polymer/metal/inorganic transparent conducting thin films fabricated on a large-area flexible polymer substrate using a continuous roll-to-roll sputtering process show excellent electrical properties and visible-light transmittance. They also exhibit water-repelling surfaces to prevent wetting and to remove contamination. In addition, the adoption of a fluorocarbon/metal/fluorocarbon film permits an outer bending radius as small as 3 mm. These films have a sheet resistance of less than 5 Ω sq(-1), sufficient to drive light-emitting diode circuits. The thin film heater with the fluorocarbon/Ag/SiNx structure exhibits excellent heating characteristics, with a temperature reaching 180 °C under the driving voltage of 13 V. Therefore, the proposed polymer/metal/polymer and polymer/metal/inorganic transparent conducting electrodes using polymer thin films can be applied in flexible and rollable displays as well as automobile window heaters and other devices.

  7. Reactions of brominated naphthalene diimide with bis(tributylstannyl)acetylene: a simple approach for conjugated polymers and versatile coupling intermediates.

    PubMed

    Alvey, Paul M; Iverson, Brent L

    2012-06-01

    A new synthetic approach to 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) containing materials and conjugates is described. A simple one-step Stille coupling procedure is used to create either novel alkyne-linked NDI polymers or a new stannylated diyne synthetic building block that provides a flexible approach to new NDI conjugates and polymers.

  8. Hot pen and laser writable photonic polymer films

    NASA Astrophysics Data System (ADS)

    Moirangthem, Monali; Stumpel, Jelle E.; Alp, Baran; Teunissen, Pit; Bastiaansen, Cees W. M.; Schenning, Albertus P. H. J.

    2016-03-01

    An orange-reflecting photonic polymer film has been fabricated based on a hydrogen-bonded cholesteric liquid crystalline (CLC) polymer consisting of non-reactive (R)-(+)-3-methyladipic acid as the chiral dopant. This polymer film can be patterned easily by evaporating the chiral dopant at specific locations with a hot pen or a laser beam. Removal of chiral dopant leads to a decrease in the helical pitch at the heat treated areas leading to a change in color from orange to green revealing a high contrast pattern. The photonic patterns are irreversible and stable at ambient conditions. This makes such a CLC polymer film interesting as writable photonic paper.

  9. Influence of Energetic Disorder on Exciton Lifetime and Photoluminescence Efficiency in Conjugated Polymers.

    PubMed

    Rörich, Irina; Mikhnenko, Oleksandr V; Gehrig, Dominik; Blom, Paul W M; Crăciun, N Irina

    2017-02-16

    Using time-resolved photoluminescence (TRPL) spectroscopy the exciton lifetime in a range of conjugated polymers is investigated. For poly(p-phenylenevinylene) (PPV)-based derivatives and a polyspirobifluorene copolymer (PSBF) we find that the exciton lifetime is correlated with the energetic disorder. Better ordered polymers exhibit a single exponential PL decay with exciton lifetimes of a few hundred picoseconds, whereas polymers with a larger degree of disorder show multiexponential PL decays with exciton lifetimes in the nanosecond regime. These observations are consistent with diffusion-limited exciton quenching at nonradiative recombination centers. The measured PL decay time reflects the time that excitons need to diffuse toward these quenching sites. Conjugated polymers with large energetic disorder and thus longer exciton lifetime also exhibit a higher photoluminescence quantum yield due to the slower exciton diffusion toward nonradiative quenching sites.

  10. Exciton dynamics in conjugated polymer photovoltaics: Steady-state and time-resolved optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Chasteen, Stephanie V.

    The performance of organic photovoltaics is severely limited by poor exciton dissociation and charge transport due in part to high rates of exciton recombination and low charge mobilities in polymers. This challenge can be partially overcome through the use of blended and layered heterojunctions. Such morphologies offer multiple exciton dissociation sites and separate charge pathways, thus limiting exciton recombination, and allowing for thicker, more absorbing, polymer films. I have performed photovoltaic device characterization and time-resolved and steady-state photoluminescence on a variety of donor-acceptor heterojunction. I have used these methods to understand excited state dynamics and how they affect device performance. As hole-transporters I use a derivative of poly-phenylene-vinylene (M3EH-PPV) and poly-3-hexylthiophene (P3HT). As electron-transporters I use the metal oxide titanium dioxide (TiO2), the electron-transporter CN-PPV, and a fullerene derivative (PCBM). These materials are layered and blended together to form donor-acceptor heterojunctions. All heterojunctions result in enhanced device performance, and 1:4 M3EH-PPV:PCBM resulted in the highest efficiencies. M3EH-PPV emission is characterized by single-chain excitations, and the decay is dominated by short components of 0.20 and 0.45 ns. CN-ether-PPV is dominated by interchain excited state species---ie., excimers---with a decay time of 14.0 ns. The broken conjugation imposed by the ether group affect the excited state, resulting in an excited state species that is particularly vulnerable to quenching. This has important ramifications for material design. Hole-transporting polymers blended and layered with CN-ether-PPV have high currents (Jsc up to 3.3 mA/cm2) and good quenching relative to CN-ether-PPV (˜90%) due to charge separation and generation, respectively. Hole-transporters blended with PCBM result in efficient devices (Jsc up to 14 mA/cm2) due to rapid charge transfer and the

  11. Dendritic polymer imaging systems for the evaluation of conjugate uptake and cleavage

    NASA Astrophysics Data System (ADS)

    Krüger, Harald R.; Nagel, Gregor; Wedepohl, Stefanie; Calderón, Marcelo

    2015-02-01

    Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular release of cargo in a cell based microplate assay that is suitable for high throughput screening.Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular

  12. Kinetic Effects on Self-Assembly and Function of Protein-Polymer Bioconjugates in Thin Films Prepared by Flow Coating.

    PubMed

    Chang, Dongsook; Huang, Aaron; Olsen, Bradley D

    2017-01-01

    The self-assembly of nanostructured globular protein arrays in thin films is demonstrated using protein-polymer block copolymers based on a model protein mCherry and the polymer poly(oligoethylene glycol acrylate) (POEGA). Conjugates are flow coated into thin films on a poly(ethylene oxide) grafted Si surface, forming self-assembled cylindrical nanostructures with POEGA domains selectively segregating to the air-film interface. Long-range order and preferential arrangement of parallel cylinders templated by selective surfaces are demonstrated by controlling relative humidity. Long-range order increases with coating speed when the film thicknesses are kept constant, due to reduced nucleation per unit area of drying film. Fluorescence emission spectra of mCherry in films prepared at <25% relative humidity shows a small shift suggesting that proteins are more perturbed at low humidity than high humidity or the solution state.

  13. Kinetic Effects on Self-Assembly and Function of Protein-Polymer Bioconjugates in Thin Films Prepared by Flow Coating

    SciTech Connect

    Chang, Dongsook; Huang, Aaron; Olsen, Bradley D.

    2016-11-04

    The self-assembly of nanostructured globular protein arrays in thin films is demonstrated using protein–polymer block copolymers based on a model protein mCherry and the polymer poly(oligoethylene glycol acrylate) (POEGA). Conjugates are flow coated into thin films on a poly(ethylene oxide) grafted Si surface, forming self-assembled cylindrical nanostructures with POEGA domains selectively segregating to the air–film interface. Long-range order and preferential arrangement of parallel cylinders templated by selective surfaces are demonstrated by controlling relative humidity. Long-range order increases with coating speed when the film thicknesses are kept constant, due to reduced nucleation per unit area of drying film. Fluorescence emission spectra of mCherry in films prepared at <25% relative humidity shows a small shift suggesting that proteins are more perturbed at low humidity than high humidity or the solution state.

  14. Highly efficient and reversible iodine capture using a metalloporphyrin-based conjugated microporous polymer.

    PubMed

    A, Sigen; Zhang, Yuwei; Li, Zhongping; Xia, Hong; Xue, Ming; Liu, Xiaoming; Mu, Ying

    2014-08-11

    A new metalloporphyrin-based conjugated microporous polymer, NiP-CMP, was constructed via a homo-coupling polymerization reaction. NiP-CMP possesses a high BET surface area of over 2600 m(2) g(-1), a large pore volume of 2.288 cm(3) g(-1), good stability, and displays excellent guest uptake of 202 wt% in iodine vapour. We also highlight that the polymer exhibits outstanding performance for the reversible adsorption of iodine in solution.

  15. Low-Dimensional Conduction Mechanisms in Highly Conductive and Transparent Conjugated Polymers.

    PubMed

    Ugur, Asli; Katmis, Ferhat; Li, Mingda; Wu, Lijun; Zhu, Yimei; Varanasi, Kripa K; Gleason, Karen K

    2015-08-19

    Electronic conduction in conjugated polymers is of emerging technological interest for high-performance optoelectronic and thermoelectric devices. A completely new aspect and understanding of the conduction mechanism on conducting polymers is introduced, allowing the applicability of materials to be optimized. The charge-transport mechanism is explained by direct experimental evidence with a very well supported theoretical model. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm2/Vs.

    PubMed

    Smith, Jeremy; Zhang, Weimin; Sougrat, Rachid; Zhao, Kui; Li, Ruipeng; Cha, Dongkyu; Amassian, Aram; Heeney, Martin; McCulloch, Iain; Anthopoulos, Thomas D

    2012-05-08

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm(2) /Vs, current on/off ratio ≥10(6) and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film.

  17. Modification and characterization of fluorescent conjugated polymer nanoparticles for single molecule detection

    NASA Astrophysics Data System (ADS)

    Zheng, Yueli

    Single molecule tracking using fluorescent dye or nanoparticle labels has emerged as a useful technique for probing biomolecular processes. Considerable interest arises in the development of nanoparticle labels with brighter fluorescence in order to improve the spatial and temporal resolution of single molecule detection and to facilitate the application of single molecule detection methods to a wider range of intracellular processes. The McNeill laboratory recently reported that conjugated polymer nanoparticles exhibit fluorescence cross-sections roughly 10--100 times higher than other luminescent nanoparticles of similar size, excellent photostability (2.2x108 photons emitted per nanoparticle prior to photobleaching), and saturated emission rates roughly 100 times higher than that of the molecular dyes and more than 1000 times higher than that of colloidal semiconductor quantum dots. One purpose of this graduate research is the development of highly fluorescent, bioconjugated nanoparticle labels based on conjugated polymers for demanding fluorescence applications such as single molecule tracking in live cells. Three surface modification methods (conjugated polymer nanoparticles encapsulated with lipid silica agents, conjugated polymer nanoparticles encapsulated with tetraethyl orthosilicate(TEOS) and hybrid nanoparticles with thiol pendant groups by the Stober Method (3-mercaptopropyl trimethoxysilane (MPS))) have been developed to protect the conjugated polymer, passivate the nanoparticle surface, and provide a chemical handle for bioconjugation such as nanoparticle encapsulation with alkoxysilanes and Stober method. After encapsulation, the fluorescence quantum yield of silica-encapsulated nanoparticles is improved by 20% as compared to bare conjugated polymer nanoparticles, while the photostability is improved by a factor of 2, indicating that some protection of the polymer is provided by the encapsulating layer. Another purpose of my research is the

  18. Altering the Conjugation Pathway for Improved Performance of Benzobisoxazole-Based Polymer Guest Emitters in Polymer Light-Emitting Diodes

    SciTech Connect

    Intemann, Jeremy J.; Hellerich, Emily S.; Tlach, Brian C.; Ewan, Monique D.; Barnes, Charles A.; Bhuwalka, Achala; Cai, Min; Shinar, Joseph; Shinar, Ruth; Jeffries-EL, Malika

    2012-08-27

    Benzobisoxazoles (BBOs) are known to increase the electron affinities and improve the electron transporting properties of materials containing them. However, BBO copolymers generally do not perform well as emissive guests in guest–host PLEDs due to inefficient Förster resonance energy transfer (FRET) between host and guest. The incomplete FRET results in a large amount of host emission and limits the potential efficiencies of the devices. In all previously reported BBO copolymers, the conjugation pathway was through the oxazole rings. Herein we report six new BBO copolymers with backbone connectivity directly on the central benzene ring, resulting in a conjugation pathway for the polymers that is perpendicular to the previously reported pathway. Guest–host PLEDs made using these polymers show that the new conjugation pathway improves FRET between the poly(N-vinylcarbazole) host and the BBO-containing polymer guest. Because of highly efficient FRET, no host emission is observed even at lower guest concentrations. The improved energy transfer results in devices with luminous efficiencies up to 3.1 Cd/A, a 3-fold improvement over previously reported BBO-based PLEDs. These results indicate that the conjugation pathway plays a critical role in designing emissive materials for guest–host PLEDs.

  19. Toward intrinsically stretchable organic semiconductors: mechanical properties of high-performance conjugated polymers

    NASA Astrophysics Data System (ADS)

    Sawyer, Eric J.; Savagatrup, Suchol; O'Connor, Timothy F.; Makaram, Aditya S.; Burke, Daniel J.; Zaretski, Aliaksandr V.; Printz, Adam D.; Lipomi, Darren J.

    2014-10-01

    This paper describes several approaches to understanding and improving the response of π-conjugated (semiconducting) polymers to tensile strain. Our principal goal was to establish the design criteria for introducing elasticity and ductility in conjugated (semiconducting) polymers through a rigorous analysis of the structural determinants of the mechanical properties of this type of material. We elucidated the details of the effect of the alkyl side chain length on the mechanical properties of regioregular polythiophene and used this analysis to select materials for stretching and transfer printing of organic solar cells to hemispherical substrates. This demonstration represents the first time that a conjugated polymer device has ever been stretched and conformally bonded to a complex 3D surface (i.e., other than a cone or cylinder, for which flexibility—as opposed to stretchability—is sufficient). We then further explored the details of the dependence of the mechanical properties on the side chain of a semiconducting polymer by synthesizing a series of hybrid materials (block and random copolymers) containing both short and long side chains. This analysis revealed the unusual semiconducting polymer, poly(3-heptylthiophene), as having an excellent combination of mechanical and electronic properties. In parallel, we explored a new method of producing "blocky" copolymers using a new procedure based on random segmentation of conjugated monomers. We found that introduction of structural randomness increased the elasticity without having detrimental effects on the photovoltaic performance. We also describe methods of synthesizing large volumes of conjugated polymers in environmentally benign ways that were amenable to manufacturing.

  20. Low-bandgap conjugated polymers enabling solution-processable tandem solar cells

    NASA Astrophysics Data System (ADS)

    Li, Gang; Chang, Wei-Hsuan; Yang, Yang

    2017-08-01

    The technology of polymer-based organic photovoltaic (OPV) cells has made great progress in the past decade, with the power conversion efficiency increasing from just a few per cent to around 12%, and the stability increasing from hours to years. One of the important milestones in this progress has been the invention of infrared-absorbing low-bandgap polymers, which allows the OPV cells to form effective tandem structures for harvesting near-infrared energy from the solar spectrum. In this Review, we focus on the progress in low-bandgap conjugated polymers and several tandem OPV cells enabled by these low-bandgap polymers. Specifically, we cover polymer-based tandem solar cells; hybrid tandem solar cells combining polymers with hydrogenated amorphous silicon; and unconventional solar cells. For each of these technologies, we address the challenges and offer our perspectives for future development.

  1. Precursors for the polymer-assisted deposition of films

    DOEpatents

    McCleskey, Thomas M.; Burrell, Anthony K.; Jia, Quanxi; Lin, Yuan

    2013-09-10

    A polymer assisted deposition process for deposition of metal oxide films is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  2. Exciton quenching close to polymer-vacuum interface of spin-coated films of poly(p-phenylenevinylene) derivative.

    PubMed

    Mikhnenko, Oleksandr V; Cordella, Fabrizio; Sieval, Alexander B; Hummelen, Jan C; Blom, Paul W M; Loi, Maria Antonietta

    2009-07-09

    Polymer-fullerene bilayer heterostructures are suited to study excitonic processes in conjugated polymers. Excitons are efficiently quenched at the polymer-fullerene interface, whereas the polymer-vacuum interface is often considered as an exciton-reflecting interface. Here, we report about efficient exciton quenching close to the polymer-vacuum interface of spin-coated MDMO-PPV (poly[2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylene]) films. The quenching efficiency is estimated to be as high as that of the polymer-fullerene interface. This efficient quenching is consistent with enhanced intermolecular interactions close to the polymer-vacuum interface due to the formation of a "skin layer" during the spin-coating procedure. In the skin layer, the polymer density is higher; that is, the intermolecular distances are shorter than in the rest of the film. The effect of exciton quenching at the polymer-vacuum interface should be taken into account when the thickness of the polymer film is on the order of the exciton diffusion length; in particular, in the determination of the exciton diffusion length.

  3. Research of spin-orbit interaction in organic conjugated polymers

    NASA Astrophysics Data System (ADS)

    Li, H.; Zhou, M. Y.; Wu, S. Y.; Liang, X. R.

    2017-06-01

    The effect of spin-orbit interaction on the one-dimensional organic polymer was investigated theoretically. Spin-orbital interaction led to the spatial separation of energy band but did not eliminate spin degeneration, which was different from energy level splitting in the Zeeman Effect. Spin-orbit interaction had little effect on the energy band structure, charge density, and lattice position, etc.; Spin precession was obtained when a polaron was transported along the polymer chain, which theoretically proved that it was feasible to control the spin precession of polaron in organic polymers by the use of external electric field.

  4. π-Conjugated Organometallic Isoindigo Oligomer and Polymer Chromophores: Singlet and Triplet Excited State Dynamics and Application in Polymer Solar Cells.

    PubMed

    Goswami, Subhadip; Gish, Melissa K; Wang, Jiliang; Winkel, Russell W; Papanikolas, John M; Schanze, Kirk S

    2015-12-09

    An isoindigo based π-conjugated oligomer and polymer that contain cyclometalated platinum(II) "auxochrome" units were subjected to photophysical characterization, and application of the polymer in bulk heterojunction polymer solar cells with PCBM acceptor was examined. The objective of the study was to explore the effect of the heavy metal centers on the excited state properties, in particular, intersystem crossing to a triplet (exciton) state, and further how this would influence the performance of the organometallic polymer in solar cells. The materials were characterized by electrochemistry, ground state absorption, emission, and picosecond-nanosecond transient absorption spectroscopy. Electrochemical measurements indicate that the cyclometalated units have a significant impact on the HOMO energy level of the chromophores, but little effect on the LUMO, which is consistent with localization of the LUMO on the isoindigo acceptor unit. Picosecond-nanosecond transient absorption spectroscopy reveals a transient with ∼100 ns lifetime that is assigned to a triplet excited state that is produced by intersystem crossing from a singlet state on a time scale of ∼130 ps. This is the first time that a triplet state has been observed for isoindigo π-conjugated chromophores. The performance of the polymer in bulk heterojunction solar cells was explored with PC61BM as an acceptor. The performance of the cells was optimum at a relatively high PCBM loading (1:6, polymer:PCBM), but the overall efficiency was relatively low with power conversion efficiency (PCE) of 0.22%. Atomic force microscopy of blend films reveals that the length scale of the phase separation decreases with increasing PCBM content, suggesting a reason for the increase in PCE with acceptor loading. Energetic considerations show that the triplet state in the polymer is too low in energy to undergo charge separation with PCBM. Further, due to the relatively low LUMO energy of the polymer, charge transfer

  5. Structure in Thin and Ultrathin Spin-Cast Polymer Films

    NASA Astrophysics Data System (ADS)

    Frank, C. W.; Rao, V.; Despotopoulou, M. M.; Pease, R. F. W.; Hinsberg, W. D.; Miller, R. D.; Rabolt, J. F.

    1996-08-01

    The molecular organization in ultrathin polymer films (thicknesses less than 1000 angstroms) and thin polymer films (thicknesses between 1000 and 10,000 angstroms) may differ substantially from that of bulk polymers, which can lead to important differences in resulting thermophysical properties. Such constrained geometry films have been fabricated from amorphous poly(3-methyl-4-hydroxy styrene) (PMHS) and semicrystalline poly(di-n-hexyl silane) (PD6S) by means of spin-casting. The residual solvent content is substantially greater in ultrathin PMHS films, which suggests a higher glass transition temperature that results from a stronger hydrogen-bonded network as compared with that in thicker films. Crystallization of PD6S is substantially hindered in ultrathin films, in which a critical thickness of 150 angstroms is needed for crystalline morphology to exist and in which the rate of crystallization is initially slow but increases rapidly as the film approaches 500 angstroms in thickness.

  6. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, Terje A.; Lee, Hung S.; Okamoto, Yoshiyuki

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  7. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, T.A.; Lee, H.S.; Okamoto, Yoshiyuki.

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  8. Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

    DOE PAGES

    Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; ...

    2016-07-19

    Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporatingmore » them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.« less

  9. A (001) dominated conjugated polymer with high-performance of hydrogen evolution under solar light irradiation.

    PubMed

    Zhou, Jun; Lei, Yanhua; Ma, Chenghai; Lv, Wenhua; Li, Na; Wang, Ying; Xu, Hu; Zou, Zhigang

    2017-09-21

    A two-dimensional imide-based conjugated polymer with a preferred (001) orientation was constructed by solvent-induced assembly. A high performance of 1640 μmol h(-1) g(-1) for solar-driven photocatalytic hydrogen evolution and an excellent stability were achieved due to tunnelling charge transport between the neighbouring molecular sheets.

  10. Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes.

    PubMed

    Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

    2016-03-02

    Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application.

  11. Super absorbent conjugated microporous polymers: a synergistic structural effect on the exceptional uptake of amines.

    PubMed

    Liu, Xiaoming; Xu, Yanhong; Guo, Zhaoqi; Nagai, Atsushi; Jiang, Donglin

    2013-04-21

    Conjugated microporous polymers exhibit a synergistic structural effect on the exceptional uptake of amines, whereas the dense porphyrin units facilitate uptake, the high porosity offers a large interface and the swellability boosts capacity. They are efficient in the uptake of both vapor and liquid amines, are applicable to various types of amines, and are excellent for cycle use.

  12. Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

    SciTech Connect

    Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

    2016-07-19

    Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.

  13. Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies.

    PubMed

    Han, Youngkyu; Carrillo, Jan-Michael Y; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S; Do, Changwoo

    2016-09-01

    Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. This study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Click-chemistry approaches to π-conjugated polymers for organic electronics applications

    PubMed Central

    Facchetti, Antonio; Lanari, Daniela; Santoro, Stefano

    2016-01-01

    Given the wide utility of click-chemistry reactions for the preparation of simple moieties within large architecturally complex materials, this minireview article aims at surveying papers exploring their scope in the area of π-conjugated polymers for application in organic electronics to enable advanced functional properties. PMID:28567241

  15. Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

    SciTech Connect

    Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

    2016-07-19

    Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.

  16. Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes

    PubMed Central

    Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

    2016-01-01

    Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

  17. Stimulation of immune systems by conjugated polymers and their potential as an alternative vaccine adjuvant.

    PubMed

    Gong, Hua; Xiang, Jian; Xu, Ligeng; Song, Xuejiao; Dong, Ziliang; Peng, Rui; Liu, Zhuang

    2015-12-07

    Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) ( PSS) exhibits a high level of cytotoxicity, polyethylene glycol (PEG) modified PSS (PEDOT:PSS-PEG) shows greatly reduced toxicity to various types of cells. To our surprise, PEGylation of PSS could obviously enhance the cellular uptake of these nanoparticles, leading to subsequent immune stimulations of both macrophages and DCs. In contrast, another type of conjugated polymer, polypyrrole (PPy), is found to be an inert material with neither significant cytotoxicity nor noticeable immune-stimulation activity. Interestingly, utilizing ovalbumin (OVA) as a model antigen, it is further uncovered in our ex vivo experiment that PSS-PEG may serve as an adjuvant to greatly enhance the immunogenicity of OVA upon simple mixing. Our study on the one hand suggests the promise of developing novel nano-adjuvants based on conjugated polymers, and on the other hand highlights the importance of careful evaluations of the impacts of any new nanomaterials developed for nanomedicine on the immune systems.

  18. Preparation of thin polymer films for infrared reaction rate studies

    NASA Technical Reports Server (NTRS)

    Garrard, G. G.; Houston, D. W.

    1970-01-01

    Procedure for preparing thin films for infrared spectrophotometric analysis involves pressing of a neat mixture of reactants between nonreactive thin polymer films with noninterfering absorption bands. Pressing is done under a pressure that gives desirable thickness. Following this process, the film sandwich is cut to accommodate the laboratory instrument.

  19. Development and Characterization of New Donor-Acceptor Conjugated Polymers and Fullerene Nanoparticles for High Performance Bulk Heterojunction Solar Cells

    DTIC Science & Technology

    2011-01-14

    Nanoparticles for High Performance Bulk Heterojunction Solar Cells Jan. 14,2011 Name of Principal Investigators: Kung-Hwa Wei - e-mail address : khwei...donor-π-bridge-acceptor side chains for high efficiency polymer solar cells . Different from the commonly used linear D-A conjugated polymers, the...Development and Characterization of New Donor-Acceptor Conjugated Polymers and Fullerene Nanoparticles for High Performance Bulk Heterojunction Solar Cells

  20. Phase Equilibria in Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Müller, M.; Binder, K.; Albano, E. V.

    Within self-consistent field theory and Monte Carlo simulations the phase behavior of a symmetrical binary AB polymer blend confined into a thin film is studied. The film surfaces interact with the monomers via short ranged potentials. One surface attracts the A component and the corresponding semi-infinite system exhibits a first order wetting transition. The surface interaction of the opposite surface is varied as to study the crossover from capillary condensation for symmetric surface fields to interface localization/delocalization transition for antisymmetric surface fields. In the former case the phase diagram has a single critical point close to the bulk critical point. In the latter case the phase diagram exhibits two critical points which correspond to the prewetting critical points of the semi-infinite system. Only below a triple point there is a single two-phase coexistence region. The crossover between these qualitatively different limiting behaviors occurs gradually, however, the critical temperature and the critical composition exhibit a non-monotonic dependence on the surface field. The dependence of the phase behavior for antisymmetric boundaries is studied as a function of the film thickness and the strength of the surface interactions. Upon reducing the film thickness or decreasing the strength of the surface interactions we can change the order of the interface localization/delocalization transition from first to second. The role of fluctuations is explored via Monte Carlo simulations of a coarse grained lattice model. Close to the (prewetting) critical points we observe 2D Ising critical behavior. Also, there is a rich crossover behavior between Ising critical, tricritical and mean field behavior. At lower temperatures capillary waves of the AB interface lead to a pronounced dependence of the effective interface potential on the lateral system size.

  1. Light-emitting diodes based on conjugated polymers

    NASA Astrophysics Data System (ADS)

    Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R. N.; Mackay, K.

    1990-10-01

    It is shown here that poly(p-phenylene vinylene), prepared by way of a solution-processable precursor, can be used as the active element in a large-area LED. The combination of good structural properties of this polymer, its ease of fabrication, and light emission in the green-yellow part of the spectrum with reasonably high efficiency suggest that the polymer can be used for the development of large-area light-emitting displays.

  2. Thermochemical study of amino acid imprinted polymer films.

    PubMed

    Chai, Ziyi; BelBruno, Joseph J

    2015-11-01

    Molecularly imprinted polymers provide an alternative to traditional methods of amino acid analysis. The imprinted polymers are more robust and significantly less expensive than, for example, ELISA analysis. Amino acid imprinted nylon-6 thin films were studied by differential scanning calorimetry and scanning electron microscopy. Endothermic peaks were observed for imprinted films at temperatures higher than that for pure nylon, indicating the formation of a more-ordered, hydrogen bonded polymer. Removal of the amino acid from the imprinted film resulted in reversion to the peak observed for pure nylon-6. Additives, β-cyclodextrin and multiwalled carbon nanotubes, were added to the imprinted polymer solutions as a means to increase the porosity of the films. These studies resulted in alternative morphologies and calorimetric results that provide additional functionalities and applications for imprinted polymers.

  3. Research on the electronic and optical properties of polymer and other organic molecular thin films

    SciTech Connect

    1997-02-01

    The main goal of the work is to find materials and methods of optimization of organic layered electroluminescent cells and to study such properties of polymers and other organic materials that can be used in various opto-electronic devices. The summary of results obtained during the first year of work is presented. They are: (1) the possibility to produce electroluminescent cells using a vacuum deposition photoresist technology for commercial photoresists has been demonstrated; (2) the idea to replace the polyaryl polymers by other polymers with weaker hole conductivity for optimization of electroluminescent cells with ITO-Al electrodes has been suggested. The goal is to obtain amorphous processable thin films of radiative recombination layers in electroluminescent devices; (3) procedures of preparation of high-quality vacuum-deposited poly (p-phenylene) (PPP) films on various substrates have been developed; (4) it was found for the first time that the fluorescence intensity of PPP films depends on the degree of polymerization; (5) the role of interfaces between organic compounds, on one side, and metals or semiconductors, on the other side, has been studied and quenching of the fluorescence caused by semiconductor layer in thin sandwiches has been observed; (6) studies of the dynamics of photoexcitations revealed the exciton self-trapping in quasi-one-dimensional aggregates; and (7) conditions for preparation of highly crystalline fullerene C{sub 60} films by vacuum deposition have been found. Composites of C{sub 60} with conjugated polymers have been prepared.

  4. Enhancing charge storage of conjugated polymer electrodes with phenolic acids

    NASA Astrophysics Data System (ADS)

    Wagner, Michal; Rębiś, Tomasz; Inganäs, Olle

    2016-01-01

    We here present studies of electrochemical doping of poly(1-aminoanthraquinone) (PAAQ) films with three structurally different phenolic acids. The examined phenolic acids (sinapic, ferulic and syringic acid) were selected due to their resemblance to redox active groups, which can be found in lignin. The outstanding electrochemical stability of PAAQ films synthesized for this work enabled extensive cycling of phenolic acid-doped PAAQ films. Potentiodynamic and charge-discharge studies revealed that phenolic acid-doped PAAQ films exhibited enhanced capacitance in comparison to undoped PAAQ films, together with appearance of redox activity characteristics specific for each dopant. Electrochemical kinetic studies performed on microelectrodes affirmed the fast electron transfer for hydroquinone-to-quinone reactions with these phenolic compounds. These results imply the potential application of phenolic acids in cheap and degradable energy storage devices.

  5. The thin-film deposition of conjugated molecules for organic electronics

    NASA Astrophysics Data System (ADS)

    Jin, Michael H.-C.

    2008-06-01

    Device-quality conjugated organic thin films are now routinely prepared in many different ways to fabricate light-emitting diodes, thin-film transistors, and photovoltaic devices. Understanding how to design molecules through versatile synthetic chemistry and the mechanisms of phase transformation and chemical reaction that occur during the thin-film deposition process becomes especially vital for the performance of the applications. This article reviews the current understanding of various thin-film deposition technologies for the conjugated organic molecules primarily used in optoelectronics, particularly in photovoltaic applications.

  6. Poled polymer films for nonlinear optics

    SciTech Connect

    Singer, K.D.; Kuzyk, M.G.; Holland, W.R.; Cahill, P.A.

    1989-01-01

    Second harmonic generation was measured for a thin corona-poled film of a dicyanovinyl azo dye incorporated in the side-chain methacrylate polymer. Measurements were performed at a wavelength of 1.58 ..mu..m as a function of incident angle for both p- and s-polarized incident light. From these measurements the form and magnitude of the second harmonic coefficient tensor were determined. The molecular distribution implied by the data is consistent with a thermodynamic potential containing only the dipolar orienting energy acting during poling. We have also demonstrated anomalous-dispersion phase-matched second harmonic generation for the first time using electric field induced second harmonic generation (EFISH) in a liquid solution of Foron Brilliant Blue S-R (FBB). Results are described. 10 refs., 4 figs., 2 tabs.

  7. Enzyme immobilization on reactive polymer films.

    PubMed

    Cordeiro, Ana L; Pompe, Tilo; Salchert, Katrin; Werner, Carsten

    2011-01-01

    Immobilized enzymes are currently used in many bioanalytical and biomedical applications. This protocol describes the use of thin films of maleic anhydride copolymers to covalently attach enzymes directly to solid supports at defined concentrations. The concentration and activity of the surface-bound enzymes can be tuned over a wide range by adjusting the concentration of enzyme used for immobilization and the physicochemical properties of the polymer platform, as demonstrated here for the proteolytic enzyme Subtilisin A. The versatile method presented allows for the immobilization of biomolecules containing primary amino groups to a broad variety of solid carriers, ranging from silicon oxide surfaces to standard polystyrene well plates and metallic surfaces. The approach can be used to investigate the effects of immobilized enzymes on cell adhesion, and on the catalysis of specific reactions.

  8. Mechanistic studies of the structure-photostability relationship of organic conjugated polymers

    NASA Astrophysics Data System (ADS)

    Sanow, Logan Paul

    Organic Conjugated polymers (CPs) are a subject of intense research for their application in organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), solid-state dye lasing, biological imaging and sensing, chemical sensing and remote sensing. CPs are key materials in the quest for more sustainable forms of renewable energy, making electronics more versatile and light weight, and increasing the functionality of everyday materials. For these applications and others that use CPs as the photoactive material, one of their main drawbacks is their susceptibility to photodegradation. Photodegradation occurs when the material is exposed to light leading to irreversible changes in the materials, most often resulting from photoxidation. These irreversible changes cause loss of mechanical, electronic and photophysical characteristics. For practical applications of CP devices, lifetime is as important as device efficiency. The following research is focused on studying the photodegradation mechanisms in various CPs to better understand the relationship between structure and stability, which may lead to the design of CPs which are more intrinsically photostable. To study how dependent photostability is on a polymer's chemical structure and frontier orbital energies, two series of CPs were studied. The first series contained two dicyano-substituted polyphenylenevinylene polymers with different side chains: poly(2,5-dioctyl-1,4-phenylene-1,2-dicyanovinylene) (C8-diCN-PPV) and poly(2,5-bis(decyloxy)-1,4-phenylene-1,2-dicyanovinylene) (RO-diCN-PPV). The second series included a well-known polymer, poly(3-hexylthiophene) (P3HT), and a newly synthesized CP, Poly(3,5-didodecyl-cyclopenta[2,1-b;3,4-b']dithiophen-4-one) (C6-CPDTO). The photodegradation mechanisms were studied through a combination of UV-Vis, PL, FTIR and NMR spectroscopy as well as gel permeation chromatography. There are two main degradation mechanisms that lead to photodegradation of CPs, the radical

  9. Noncovalent Se···O Conformational Locks for Constructing High-Performing Optoelectronic Conjugated Polymers.

    PubMed

    Dong, Tao; Lv, Lei; Feng, Linlin; Xia, Yu; Deng, Wei; Ye, Pan; Yang, Bei; Ding, Shang; Facchetti, Antonio; Dong, Huanli; Huang, Hui

    2017-09-01

    Noncovalent conformational locks are broadly employed to construct highly planar π-conjugated semiconductors exhibiting substantial charge transport characteristics. However, current chalcogen-based conformational lock strategies for organic semiconductors are limited to S···X (X = O, N, halide) weak interactions. An easily accessible (minimal synthetic steps) and structurally planar selenophene-based building block, 1,2-diethoxy-1,2-bisselenylvinylene (DESVS), with novel Se···O noncovalent conformational locks is designed and synthesized. DESVS unique properties are supported by density functional theory computed electronic structures, single crystal structures, and experimental lattice cohesion metrics. Based on this building block, a new class of stable, structurally planar, and solution-processable conjugated polymers are synthesized and implemented in organic thin-film transistors (TFT) and organic photovoltaic (OPV) cells. DESVS-based polymers exhibit carrier mobilities in air as high as 1.49 cm(2) V(-1) s(-1) (p-type) and 0.65 cm(2) V(-1) s(-1) (n-type) in TFTs, and power conversion efficiency >5% in OPV cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Polymer-drug conjugates for intracellar molecule-targeted photoinduced inactivation of protein and growth inhibition of cancer cells

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Yuan, Huanxiang; Zhu, Chunlei; Yang, Qiong; Lv, Fengting; Liu, Libing; Wang, Shu

    2012-10-01

    For most molecule-targeted anticancer systems, intracellular protein targets are very difficult to be accessed by antibodies, and also most efforts are made to inhibit protein activity temporarily rather than inactivate them permanently. In this work we firstly designed and synthesized multifunctional polymer-drug conjugates (polythiophene-tamoxifen) for intracellular molecule-targeted binding and inactivation of protein (estrogen receptor α, ERα) for growth inhibition of MCF-7 cancer cells. Small molecule drug was conjugated to polymer side chain for intracellular signal protein targeting, and simultaneously the fluorescent characteristic of polymer for tracing the cellular uptake and localization of polythiophene-drug conjugates by cell imaging. Under light irradiation, the conjugated polymer can sensitize oxygen to produce reactive oxygen species (ROS) that specifically inactivate the targeted protein, and thus inhibit the growth of tumor cells. The conjugates showed selective growth inhibition of ERα positive cancer cells, which exhibits low side effect for our intracellular molecule-targeted therapy system.

  11. Synthesis of carboxylated poly(NIPAAm) oligomers and their application to form thermo-reversible polymer-enzyme conjugates.

    PubMed

    Chen, G; Hoffman, A S

    1994-01-01

    A thermo-reversible poly(N-isopropylacrylamide) poly(NIPAAm) oligomer with a carboxyl functional end group has been synthesized by radical polymerization using beta-mercaptopropionic acid as a chain transfer reagent. This polymer has been conjugated to an enzyme, beta-D-glucosidase, to form a thermo-reversible water soluble-insoluble polymer-enzyme conjugate. This conjugate can be used for separation, recovery and recycle of an enzyme simply by applying small temperature changes to the reaction medium. In contrast to the random polymer-enzyme conjugates reported in the literature, in this study the enzyme is coupled to each polymer chain by a single end attachment. These preliminary studies show that the conjugated enzyme exhibits very high retention of activity (> 90%) compared to the native enzyme and shows improved thermal stability.

  12. Electrospun conjugated polymer nanofibers as miniaturized light sources: control of morphology, optical properties, and assembly

    NASA Astrophysics Data System (ADS)

    Camposeo, A.; Fasano, V.; Moffa, M.; Polini, A.; Di Camillo, D.; Ruggieri, F.; Santucci, S.; Lozzi, L.; Persano, L.; Pisignano, D.

    2014-10-01

    Light-emitting nanostructures made by conjugated polymers show interesting emission and electronic properties. In this work we report on novel approaches for the fabrication and control of light-emitting nanofibers by electrospinning. The shape, size and light-emitting properties of the fibers can be specifically tailored by acting on the composition of the solution used for the electrospinning process, an approach allowing for obtaining fibers ranging from micrometer-sized ribbons to almost cylindrical fibers with diameters down to few hundreds of nanometers. Moreover, following proper process optimization these fibers can also be precisely positioned in ordered arrays by near-field electrospinning, a method that exploits the stable region of the polymer jet. The possibility of precisely shaping the conjugated polymer fibers and of assembling the fiber in ordered arrays, combined with enhanced emission properties, opens interesting perspectives for developing novel emitting flexible nanomaterials suitable for light sourcing and optical sensing.

  13. DNA detection using water-soluble conjugated polymers and peptide nucleic acid probes

    PubMed Central

    Gaylord, Brent S.; Heeger, Alan J.; Bazan, Guillermo C.

    2002-01-01

    The light-harvesting properties of cationic conjugated polymers are used to sensitize the emission of a dye on a specific peptide nucleic acid (PNA) sequence for the purpose of homogeneous, “real-time” DNA detection. Signal transduction is controlled by hybridization of the neutral PNA probe and the negative DNA target. Electrostatic interactions bring the hybrid complex and cationic polymer within distances required for Förster energy transfer. Conjugated polymer excitation provides fluorescein emission >25 times higher than that obtained by exciting the dye, allowing detection of target DNA at concentrations of 10 pM with a standard fluorometer. A simple and highly sensitive assay with optical amplification that uses the improved hybridization behavior of PNA/DNA complexes is thus demonstrated. PMID:12167673

  14. Thermogelling polymer-platinum(IV) conjugates for long-term delivery of cisplatin.

    PubMed

    Shen, Wenjia; Luan, Jiabin; Cao, Luping; Sun, Jian; Yu, Lin; Ding, Jiandong

    2015-01-12

    In this study, we suggest a novel strategy of constituting an in situ-formed hydrogel composed of polymer-platinum(IV) conjugate to realize a long-term delivery of cisplatin. A unique conjugate was designed and synthesized by covalent linking of Pt(IV) complex to the hydrophobic end of two methoxyl poly(ethylene glycol)-b-poly(d,l-lactide) (mPEG-PLA) copolymer chains, resulting in the formation of Bi(mPEG-PLA)-Pt(IV). The conjugate could self-assemble into micelles in water, and its concentrated solution exhibited a thermoreversible sol-gel transition and formed a semisolid thermogel at body temperature. The incorporation of the cisplatin analogue Pt(IV) prodrug into the conjugate had a significant influence on its thermogelling properties and the conjugate thermogelation was attributed to the micellar aggregation. In vitro release experiments of Pt(IV)-conjugated thermogel showed that the platinum release lasted as long as two months. Furthermore, we demonstrated that the Pt(IV) prodrug was released mainly in the form of micelles and micellar aggregates from the gel depot. Compared with free cisplatin, the formation of conjugate micelles led to the enhanced in vitro cytotoxicity against cancer cells due to the effective accumulation into cells via endocytosis.

  15. Intracellular delivery and trafficking dynamics of a lymphoma-targeting antibody-polymer conjugate.

    PubMed

    Berguig, Geoffrey Y; Convertine, Anthony J; Shi, Julie; Palanca-Wessels, Maria Corinna; Duvall, Craig L; Pun, Suzie H; Press, Oliver W; Stayton, Patrick S

    2012-12-03

    Ratiometric fluorescence and cellular fractionation studies were employed to characterize the intracellular trafficking dynamics of antibody-poly(propylacrylic acid) (PPAA) conjugates in CD22+ RAMOS-AW cells. The HD39 monoclonal antibody (mAb) directs CD22-dependent, receptor-mediated uptake in human B-cell lymphoma cells, where it is rapidly trafficked to the lysosomal compartment. To characterize the intracellular-release dynamics of the polymer-mAb conjugates, HD39-streptavidin (HD39/SA) was dual-labeled with pH-insensitive Alexa Fluor 488 and pH-sensitive pHrodo fluorophores. The subcellular pH distribution of the HD39/SA-polymer conjugates was quantified as a function of time by live-cell fluorescence microscopy, and the average intracellular pH value experienced by the conjugates was also characterized as a function of time by flow cytometry. PPAA was shown to alter the intracellular trafficking kinetics strongly relative to HD39/SA alone or HD39/SA conjugates with a control polymer, poly(methacryclic acid) (PMAA). Subcellular trafficking studies revealed that after 6 h, only 11% of the HD39/SA-PPAA conjugates had been trafficked to acidic lysosomal compartments with values at or below pH 5.6. In contrast, the average intracellular pH of HD39/SA alone dropped from 6.7 ± 0.2 at 1 h to 5.6 ± 0.5 after 3 h and 4.7 ± 0.6 after 6 h. Conjugation of the control polymer PMAA to HD39/SA showed an average pH drop similar to that of HD39/SA. Subcellular fractionation studies with tritium-labeled HD39/SA demonstrated that after 6 h, 89% of HD39/SA was associated with endosomes (Rab5+) and lysosomes (Lamp2+), while 45% of HD39/SA-PPAA was translocated to the cytosol (lactate dehydrogenase+). These results demonstrate the endosomal-releasing properties of PPAA with antibody-polymer conjugates and detail their intracellular trafficking dynamics and subcellular compartmental distributions over time.

  16. Optical Properties of Silver Particulate Films on Modified Polymer Substrates

    NASA Astrophysics Data System (ADS)

    Gurumurthy, S. C.; Pattabi, Manjunatha; Sanjeeva, Ganesh

    2011-07-01

    Results of the investigations carried out on the optical properties of particulate films deposited on 8 MeV electron beam irradiated polystyrene (PS) and on blends of PS and Poly (4-vinyl pyridine) (P4VP) are reported. It is observed that absorption maxima shift towards higher wavelength for films deposited on irradiated polystyrene and on blends of PS and P4VP. These results indicate that morphology of the particulate films can be changed by tuning the metal polymer interaction in an inert polymer through electron beam irradiation or by blending it with an interacting polymer like P4VP.

  17. 11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor.

    PubMed

    Bin, Haijun; Gao, Liang; Zhang, Zhi-Guo; Yang, Yankang; Zhang, Yindong; Zhang, Chunfeng; Chen, Shanshan; Xue, Lingwei; Yang, Changduk; Xiao, Min; Li, Yongfang

    2016-12-01

    Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si-C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0.94 V and high short circuit current density of 17.32 mA cm(-2) benefitted from the complementary absorption of the donor and acceptor, and the high hole transfer efficiency from acceptor to donor although the highest occupied molecular orbital level difference between the donor and acceptor is only 0.11 eV. The results indicate that the alkylsilyl substitution is an effective way in designing high performance conjugated polymer photovoltaic materials.

  18. 11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor

    PubMed Central

    Bin, Haijun; Gao, Liang; Zhang, Zhi-Guo; Yang, Yankang; Zhang, Yindong; Zhang, Chunfeng; Chen, Shanshan; Xue, Lingwei; Yang, Changduk; Xiao, Min; Li, Yongfang

    2016-01-01

    Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si–C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0.94 V and high short circuit current density of 17.32 mA cm−2 benefitted from the complementary absorption of the donor and acceptor, and the high hole transfer efficiency from acceptor to donor although the highest occupied molecular orbital level difference between the donor and acceptor is only 0.11 eV. The results indicate that the alkylsilyl substitution is an effective way in designing high performance conjugated polymer photovoltaic materials. PMID:27905397

  19. 11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor

    NASA Astrophysics Data System (ADS)

    Bin, Haijun; Gao, Liang; Zhang, Zhi-Guo; Yang, Yankang; Zhang, Yindong; Zhang, Chunfeng; Chen, Shanshan; Xue, Lingwei; Yang, Changduk; Xiao, Min; Li, Yongfang

    2016-12-01

    Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si-C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0.94 V and high short circuit current density of 17.32 mA cm-2 benefitted from the complementary absorption of the donor and acceptor, and the high hole transfer efficiency from acceptor to donor although the highest occupied molecular orbital level difference between the donor and acceptor is only 0.11 eV. The results indicate that the alkylsilyl substitution is an effective way in designing high performance conjugated polymer photovoltaic materials.

  20. "Graft-to" Protein/Polymer Conjugates Using Polynorbornene Block Copolymers.

    PubMed

    Isarov, Sergey A; Lee, Parker W; Pokorski, Jonathan K

    2016-02-08

    A series of water-soluble polynorbornene block copolymers prepared via Ring-Opening Metathesis Polymerization (ROMP) were grafted to proteins to form ROMP-derived bioconjugates. ROMP afforded low-dispersity polymers and allowed for strict control over polymer molecular weight and architecture. The polymers consisted of a large block of PEGylated monoester norbornene and were capped with a short block of norbornene dicarboxylic anhydride. This cap served as a reactive linker that facilitated attachment of the polymer to lysine residues under mildly alkaline conditions. The generality of this approach was shown by synthesizing multivalent polynorbornene-modified viral nanoparticles derived from bacteriophage Qβ, a protein nanoparticle used extensively for nanomedicine. The conjugated nanoparticles showed no cytotoxicity to NIH 3T3 murine fibroblast cells. These findings establish protein bioconjugation with functionalized polynorbornenes as an effective alternative to conventional protein/polymer modification strategies and further expand the toolbox for protein bioconjugates.

  1. Cysteine-functional polymers via thiol-ene conjugation.

    PubMed

    Kuhlmann, Matthias; Reimann, Oliver; Hackenberger, Christian P R; Groll, Jürgen

    2015-03-01

    A thiofunctional thiazolidine is introduced as a new low-molar-mass building block for the introduction of cysteine residues via a thiol-ene reaction. Allyl-functional polyglycidol (PG) is used as a model polymer to demonstrate polymer-analogue functionalization through reaction with the unsaturated side-chains. A modified trinitrobenzenesulfonic acid (TNBSA) assay is used for the redox-insensitive quantification and a precise final cysteine content can be predetermined at the polymerization stage. Native chemical ligation at cysteine-functional PG is performed as a model reaction for a chemoselective peptide modification of this polymer. The three-step synthesis of the thiofunctional thiazolidine reactant, together with the standard thiol-ene coupling and the robust quantification assay, broadens the toolbox for thiol-ene chemistry and offers a generic and straightforward approach to cysteine-functional materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Low bandgap conjugated polymers for organic solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Tao

    Organic solar cells are emerging as a potential solution to address the energy issue in the future. Functional materials that can achieve high performance are the main topics in my thesis. I went briefly to introduce the background and history first, emphasizing on the synthetic principles towards high performance copolymers. My second chapters is about the perturbation effect by introducing terminal chloroaryl in the side chain. A new type of monomer is presented in Chapter III and corresponding polymers are studied. Then we investigated the impact of polymerization conditions on the physical properties using PTB7 as the standard polymer. In the last, we further utilized TID unit to construct acceptor polymers and random copolymer. A PCE value of 7.55% was achieved.

  3. Characterization of polymer films for use in bimorph chemical sensors

    NASA Astrophysics Data System (ADS)

    Chatzandroulis, S.; Goustouridis, D.; Raptis, I.

    2005-01-01

    In the present work white light interferometry is applied for the characterization of polymer films commonly used in bimorph chemical sensors. The study focuses on methacrylate polymers with positive tone patterning capabilities. The behavior upon exposure to controlled concentrations volatile organic compound and water vapors of thin poly (hydroxy ethyl methacrylate) (PHEMA) and poly (methyl methacrylate) (PMMA) layers was evaluated. The normalized film expansion for PHEMA, compared to PMMA, is higher in the case of water and methanol vapors, almost equal for ethanol and significantly lower in the case of acetone. This behavior could be attributed to the combination of polarity and hydrogen bonding capability of the analytes. A wide polymer film thickness range was examined and it was revealed that the normalized film expansion in both PHEMA and PMMA is nearly constant for films thicker than 100 nm and increases for thinner films.

  4. New paradigm for stabilization of liquid polymer films on solids

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Jiang, Naisheng; Wang, Jiaxun; di, Xiaoyu; Cheung, Justin; Endoh, Maya

    2015-03-01

    We report that wetting/dewetting behavior of liquid polymer films on solids can be controlled by nanoscale architectures of polymer chains irreversibly adsorbed on the impenetrable surfaces. Monodisperse polystyrene (PS) ultrathin films (20 nm in thickness) with different molecular weights on silicon (Si) substrates with a natural amorphous Si dioxide layer were used as models. The PS thin films were annealed at high temperatures at T>Tg (Tg is the bulk glass transition temperature) for several days, and the surface structures were studied by using optical and atomic force microscopes. At the same time, the annealed PS films were further leached with a good solvent and the residue films (i.e., irreversibly adsorbed layers) were characterized by x-ray reflectivity. The experimental data reveals a strong correlation between the conformations of the adsorbed polymer chains and the stability of the liquid films on top. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  5. Electrocatalytic hydrogenation using precious metal microparticles in redox-active polymer films

    SciTech Connect

    Coche, L.; Ehui, B.; Limosin, D.; Moutet, J.C. )

    1990-11-09

    Glassy carbon felt electrodes have been modified by electrodeposition of poly(pyrrole-viologen) films (derived from N,N{prime}-dialkyl-4,4{prime}-bipyridinium salts), followed by electroprecipitation of precious metal (Pt, Pd, Rh, or Ru) microparticles. The resulting electrodes have been proved to be active for the electrocatalytic hydrogenation of conjugated enones (2-cyclohexen-1-one, cryptone, carvone, isophorone), styrene, and benzonitrile in aqueous media (pH 1). Despite low loadings of metal catalysts, high electric and products yields and a long term stability of these cathodes have been observed. The influence of the metal loading and the polymer structure on the catalytic efficiency as well as the selectivity obtained according to the metal catalyst used have been studied. Comparison with results previously reported for other catalytic cathodes like Pt/Pt, Pd/C, or Raney nickel electrodes proves the high efficiency of these metal microparticles within redox polymer film based electrodes.

  6. RESEARCH ON THE ELECTRONIC AND OPTICAL PROPERTIES OF POLYMER AND OTHER ORGANIC MOLECULAR THIN FILMS

    SciTech Connect

    ALEXEI G. VITUKHNOVSKY; IGOR I. SOBELMAN - RUSSIAN ACADEMY OF SCIENCES

    1995-09-06

    Optical properties of highly ordered films of poly(p-phenylene) (PPP) on different substrates, thin films of mixtures of conjugated polymers, of fullerene and its composition with polymers, molecular J-aggregates of cyanine dyes in frozen matrices have been studied within the framework of the Agreement. Procedures of preparation of high-quality vacuum deposited PPP films on different substrates (ITO, Si, GaAs and etc.) were developed. Using time-correlated single photon counting technique and fluorescence spectroscopy the high quality of PPP films has been confirmed. Dependence of structure and optical properties on the conditions of preparation were investigated. The fluorescence lifetime and spectra of highly oriented vacuum deposited PPP films were studied as a function of the degree of polymerization. It was shown for the first time that the maximum fluorescence quantum yield is achieved for the chain length approximately equal to 35 monomer units. The selective excitation of luminescence of thin films of PPP was performed in the temperature range from 5 to 300 K. The total intensity of luminescence monotonically decreases with decreasing temperature. Conditions of preparation of highly cristallyne fullerene C{sub 60} films by the method of vacuum deposition were found. Composites of C{sub 60} with conjugated polymers PPV and polyacetylene (PA) were prepared. The results on fluorescence quenching, IR and resonant Raman spectroscopy are consistent with earlier reported ultrafast photoinduced electron transfer from PPV to C{sub 60} and show that the electron transfer is absent in the case of the PA-C{sub 60} composition. Strong quenching of PPV fluorescence was observed in the PPV-PA blends. The electron transfer from PPV to PA can be considered as one of the possible mechanisms of this quenching. The dynamics of photoexcitations in different types of J-aggregates of the carbocyanine dye was studied at different temperatures in frozen matrices. The optical

  7. Ferritin-Polymer Conjugates: Grafting Chemistry and Self-Assembly

    DTIC Science & Technology

    2009-10-26

    polymer core-shell structures by co-assembly. 9 A numbers of BNPs including cowpea mosaic virus, turnip yellow mosaic virus, and bacteriophage P22...Figure 11. Synthetic route for fluorescent crosslinkers. Turnip yellow mosaic virus (TYMV), a plant virus with unique structural and chemical

  8. Modified extended Hückel band calculations on conjugated polymers

    NASA Astrophysics Data System (ADS)

    Hong, Sung Y.; Marynick, Dennis S.

    1992-04-01

    In order to more accurately predict band gaps, corresponding to π-π* transitions of one-dimensional conducting polymers, the formula for the off-diagonal elements, Hαβij in the extended Hückel (EH) band calculation method was modified according to the form Hαβij=K1(Hααii +Hββjj)exp(-K2Rαβ) Sαβij. Parametrizations for the constants K1 and K2 were performed so as to yield reasonable band gaps for the pure hydrocarbon polymers trans-polyacetylene, poly(para-phenylene), and poly(phenylene vinylene). Since there is a large difference in bond alternations along polymeric chains between ab initio and modified neglect of diatomic overlap optimized geometries, especially for heterocyclic polymers, the valence orbital exponents of oxygen, nitrogen, and sulfur were separately adjusted, depending on the chosen geometry, to reproduce the band gaps of polyfuran, polypyrrole, and polythiophene. It is found that geometrical relaxations in the presence of heteroatoms strongly affect the C1-C4 interactions as well as bond alternations, which in turn affect the band gap. Modified EH band calculations were performed for various polymers. The predicted band gaps had average errors of ca. 10% (less than 0.3 eV) compared to the experimental values, and the method produced band structures consistent with electron-energy-loss spectroscopic observations.

  9. Anisotropic Conjugated Polymer Chain Conformation Tailors the Energy Migration in Nanofibers.

    PubMed

    Camposeo, Andrea; Pensack, Ryan D; Moffa, Maria; Fasano, Vito; Altamura, Davide; Giannini, Cinzia; Pisignano, Dario; Scholes, Gregory D

    2016-11-30

    Conjugated polymers are complex multichromophore systems, with emission properties strongly dependent on the electronic energy transfer through active subunits. Although the packing of the conjugated chains in the solid state is known to be a key factor to tailor the electronic energy transfer and the resulting optical properties, most of the current solution-based processing methods do not allow for effectively controlling the molecular order, thus making the full unveiling of energy transfer mechanisms very complex. Here we report on conjugated polymer fibers with tailored internal molecular order, leading to a significant enhancement of the emission quantum yield. Steady state and femtosecond time-resolved polarized spectroscopies evidence that excitation is directed toward those chromophores oriented along the fiber axis, on a typical time scale of picoseconds. These aligned and more extended chromophores, resulting from the high stretching rate and electric field applied during the fiber spinning process, lead to improved emission properties. Conjugated polymer fibers are relevant to develop optoelectronic plastic devices with enhanced and anisotropic properties.

  10. Anisotropic Conjugated Polymer Chain Conformation Tailors the Energy Migration in Nanofibers

    PubMed Central

    2016-01-01

    Conjugated polymers are complex multichromophore systems, with emission properties strongly dependent on the electronic energy transfer through active subunits. Although the packing of the conjugated chains in the solid state is known to be a key factor to tailor the electronic energy transfer and the resulting optical properties, most of the current solution-based processing methods do not allow for effectively controlling the molecular order, thus making the full unveiling of energy transfer mechanisms very complex. Here we report on conjugated polymer fibers with tailored internal molecular order, leading to a significant enhancement of the emission quantum yield. Steady state and femtosecond time-resolved polarized spectroscopies evidence that excitation is directed toward those chromophores oriented along the fiber axis, on a typical time scale of picoseconds. These aligned and more extended chromophores, resulting from the high stretching rate and electric field applied during the fiber spinning process, lead to improved emission properties. Conjugated polymer fibers are relevant to develop optoelectronic plastic devices with enhanced and anisotropic properties. PMID:27933935

  11. A heparin-mimicking polymer conjugate stabilizes basic fibroblast growth factor

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi H.; Kim, Sung-Hye; Decker, Caitlin G.; Wong, Darice Y.; Loo, Joseph A.; Maynard, Heather D.

    2013-03-01

    Basic fibroblast growth factor (bFGF) is a protein that plays a crucial role in diverse cellular functions, from wound healing to bone regeneration. However, a major obstacle to the widespread application of bFGF is its inherent instability during storage and delivery. Here, we describe the stabilization of bFGF by covalent conjugation with a heparin-mimicking polymer, a copolymer consisting of styrene sulfonate units and methyl methacrylate units bearing poly(ethylene glycol) side chains. The bFGF conjugate of this polymer retained bioactivity after synthesis and was stable to a variety of environmentally and therapeutically relevant stressors—such as heat, mild and harsh acidic conditions, storage and proteolytic degradation—unlike native bFGF. Following the application of stress, the conjugate was also significantly more active than the control conjugate system in which the styrene sulfonate units were omitted from the polymer structure. This research has important implications for the clinical use of bFGF and for the stabilization of heparin-binding growth factors in general.

  12. Preparation of Conjugated Polymer Grafted with H2O2-Sensitive Prodrug for Cell Imaging and Tumor Cell Killing.

    PubMed

    Li, Meng; Li, Shengliang; Chen, Hui; Hu, Rong; Liu, Libing; Lv, Fengting; Wang, Shu

    2016-01-13

    In this work, a new conjugated polymer poly(fluorene-co-phenylene) derivative containing pendent quaternized chlormethine (PFP-Chl) was synthesized by covalent linking small molecular prodrug groups onto conjugated polymer side chains. H2O2-sensitive prodrug with an eight-member-cyclic boronate ester structure could suffer from H2O2-triggered nitrogen mustard release and further DNA cross-linking and alkylation. PFP-Chl combines therapeutic characteristic with excellent optical property of conjugated polymers. It is found that PFP-Chl could enter into cells by endocytosis to simultaneously exhibit abilities of fluorescent imaging and tumor cell inhibition.

  13. Acoustical performance of an electrostrictive polymer film loudspeaker

    PubMed

    Heydt; Pelrine; Joseph; Eckerle; Kornbluh

    2000-02-01

    A new type of loudspeaker that generates sound by means of the electrostrictive response of a thin polymer film is described. Electrostrictive polymer film (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have a very low profile. The films are typically silicone and are coated with compliant electrodes to allow large film deformations. Acoustical frequency response measurements from 5 x 5 cm (planar dimensions) prototype EPF loudspeakers are presented. Measurements of harmonic distortion are also shown, along with results demonstrating reduced harmonic distortion achieved with square-root wave shaping. Applications of EPF loudspeakers include active noise control and general-purpose flat-panel loudspeakers.

  14. Effectiveness of External Electric Field Treatment of Conjugated Polymers in Bulk-Heterojunction Solar Cells.

    PubMed

    Solanki, Ankur; Bagui, Anirban; Long, Guankui; Wu, Bo; Salim, Teddy; Chen, Yongsheng; Lam, Yeng Ming; Sum, Tze Chien

    2016-11-30

    External electric field treatment (EFT) on P3HT:PCBM bulk heterojunction (BHJ) devices was recently found to be a viable approach for improving the power conversion efficiencies (PCEs) through modulating the blend nanomorphology. However, its effectiveness over the broad family of polymer-fullerene blends remains unclear. Herein, we investigate the effects of external EFT on various polymer-fullerene blends with distinct morphologies stemming from the difference in molecular structure of the polymers (i.e., semicrystalline vs amorphous) in a bid to establish a clear morphology-function-charge dynamics relationship to the photovoltaic performance. Our findings reveal that EFT promotes self-organization of the semicrystalline thiophene-based conjugated polymers (i.e., P3HT and P3BT) while it was ineffective for the amorphous polymers (i.e., PTB7 and PCPDTBT) even at the maximum applied E-field of 8 kV cm(-1). Transient absorption spectroscopy shows an improvement in the initial charge-carrier and polaron formation from delocalized excitons in the E-field treated semicrystalline blends compared to their untreated reference samples. Interfacial trap-assisted monomolecular and trap-free bimolecular recombination at nanosecond-microsecond time scale in the E-field treated P3BT:PC60BM devices are significantly suppressed. Importantly, our findings shed new light and provide guidelines on the effectiveness of utilizing external EFT to enhance the PCEs of a larger family of conjugated polymer-based BHJ OSCs.

  15. Photovoltaic properties of conjugated polymer/methanofullerene composites embedded in a polystyrene matrix

    NASA Astrophysics Data System (ADS)

    Brabec, C. J.; Padinger, F.; Sariciftci, N. S.; Hummelen, J. C.

    1999-05-01

    Bulk donor-acceptor heterojunctions between conjugated polymers and fullerene derivatives have been utilized successfully for photovoltaic devices showing monochromatic energy conversion efficiencies above 1%. The photovoltaic response of these devices is based on the ultrafast, photoinduced electron transfer from the conjugated polymer to the fullerene [N. S. Sariciftci and A. J. Heeger, Handbook of Organic Conductive Molecules and Polymers, (Wiley, New York, 1997), pp. 413-455]. In this work we present efficiency data of solar cells based on a soluble derivative of p-phenylene vinylene (PPV), poly [2-methoxy, 5-(3',7'-dimethyl-octyloxy)]-p-phenylene vinylene (MDMO-PPV), and a highly soluble methanofullerene, [6,6]-phenyl C61-butyric acid methyl ester (PCBM), embedded into a conventional polymer, polystyrene (PS). By the blending of the optimized donor-acceptor components into the conventional polymer matrix, the percolation threshold for photovoltaic response of the three component systems is found to be determined by percolation of the methanofullerene in the polymer matrix. We present current/voltage data of PS-MDMO-PPV-PCBM devices with various PS concentrations as well as photoinduced absorption studies in the infrared [(PIA) Fourier transform infrared] and light induced electron spin resonance studies on the electron transfer in these composites. At low light intensities, the monochromatic power conversion efficiency ηe and the photon carrier collection efficiency ηc of the PS free device are calculated with 1.5% and 18%, respectively.

  16. Multivalent Polymers for Drug Delivery and Imaging: The Challenges of Conjugation

    PubMed Central

    2015-01-01

    Multivalent polymers offer a powerful opportunity to develop theranostic materials on the size scale of proteins that can provide targeting, imaging, and therapeutic functionality. Achieving this goal requires the presence of multiple targeting molecules, dyes, and/or drugs on the polymer scaffold. This critical review examines the synthetic, analytical, and functional challenges associated with the heterogeneity introduced by conjugation reactions as well as polymer scaffold design. First, approaches to making multivalent polymer conjugations are discussed followed by an analysis of materials that have shown particular promise biologically. Challenges in characterizing the mixed ligand distributions and the impact of these distributions on biological applications are then discussed. Where possible, molecular-level interpretations are provided for the structures that give rise to the functional ligand and molecular weight distributions present in the polymer scaffolds. Lastly, recent strategies employed for overcoming or minimizing the presence of ligand distributions are discussed. This review focuses on multivalent polymer scaffolds where average stoichiometry and/or the distribution of products have been characterized by at least one experimental technique. Key illustrative examples are provided for scaffolds that have been carried forward to in vitro and in vivo testing with significant biological results. PMID:25120091

  17. Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

    PubMed Central

    Chang, Yao-Tang; Sharma, Sunil; Hung, Miao-Ken; Lee, Yu-Hsuan; Chen, Show-An

    2016-01-01

    σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence. PMID:27910921

  18. Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

    NASA Astrophysics Data System (ADS)

    Chang, Yao-Tang; Sharma, Sunil; Hung, Miao-Ken; Lee, Yu-Hsuan; Chen, Show-An

    2016-12-01

    σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence.

  19. Self-lubricating polymer composites and polymer transfer film lubrication for space applications

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1990-01-01

    The use of self-lubricating polymers and polymer composites in space is somewhat limited today. In general, they are only used when other methods are inadequate. There is potential, however, for these materials to make a significant impact on future space missions if properly utilized. Some of the different polymers and fillers used to make self-lubricating composites are surveyed. The mechanisms of composite lubrication and wear, the theory behind transfer film lubricating mechanisms, and some factors which affect polymer composite wear and transfer are examined. In addition, some of the current space tribology application areas for self-lubricating polymer composites and polymer transfer are mentioned.

  20. Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

    NASA Astrophysics Data System (ADS)

    Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

    2011-03-01

    We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG

  1. Elements of adaptive optics based on metallized polymer films

    NASA Astrophysics Data System (ADS)

    Voliak, T. B.; Krasiuk, I. K.; Pashinin, P. P.

    Results of an experimental study of the stability of metallized polymer films exposed to laser radiation at wavelengths of 1.06 and 10.6 microns are reported, and methods for fabricating variable-curvature mirrors from these films are discussed. Formulas are presented for calculating the shape of film mirrors as a function of the pressure acting on the film, mounting contour, and film properties. The performance of film mirrors is investigated experimentally in a pulsed CO2 laser with stable and unstable resonators.

  2. Conjugation of Polymer-Coated Gold Nanoparticles with Antibodies—Synthesis and Characterization

    PubMed Central

    Tan, Gamze; Kantner, Karsten; Zhang, Qian; Soliman, Mahmoud G.; del Pino, Pablo; Parak, Wolfgang J.; Onur, Mehmet A.; Valdeperez, Daniel; Rejman, Joanna; Pelaz, Beatriz

    2015-01-01

    The synthesis of polymer-coated gold nanoparticles with high colloidal stability is described, together with appropriate characterization techniques concerning the colloidal properties of the nanoparticles. Antibodies against vascular endothelial growth factor (VEGF) are conjugated to the surface of the nanoparticles. Antibody attachment is probed by different techniques, giving a guideline about the characterization of such conjugates. The effect of the nanoparticles on human adenocarcinoma alveolar basal epithelial cells (A549) and human umbilical vein endothelial cells (HUVECs) is probed in terms of internalization and viability assays. PMID:28347065

  3. Amplified spontaneous emission from the exciplex state of a conjugated polymer "PFO" in oleic acid

    NASA Astrophysics Data System (ADS)

    Idriss, Hajo; Taha, Kamal K.; Aldaghri, O.; Alhathlool, R.; AlSalhi, M. S.; Ibnaouf, K. H.

    2016-09-01

    The amplified spontaneous emission (ASE) characteristics of a conjugated polymer poly (9, 9-dioctylfluorenyl-2, 7-diyl) (PFO) in oleic acid have been studied under different concentrations and temperatures. Here, the ASE spectra of PFO in oleic acid have been obtained using a transverse cavity configuration where the conjugated PFO was pumped by laser pulses from the third harmonic of Nd: YAG laser (355 nm). The PFO in oleic acid produces ASE from an exciplex state - a new molecular species. The obtained results were compared with the PFO in benzene. Such ASE spectra from the exciplex state have not been observed for the PFO in benzene.

  4. Development of polymer film solar collectors: A status report

    NASA Astrophysics Data System (ADS)

    Wilhelm, W. G.; Andrews, J. W.

    1982-08-01

    Solar energy collector panels using polymer film and laminate technology were developed which demonstrate low cost and high thermal performance for residential and commercial applications. This device uses common water in the absorber/heat exchanger which is constructed with polymer film adhesively laminated to aluminum foil as the outer surfaces. Stressed polymer films are also used for the outer window and back surface of the panel forming a high strength structural composite. Rigid polymer foam complements the design by contributing insulation and structural definition. This design resulted in very low weight (3.5 kg/m(2)), potentially very low manufacturing cost (aprox. $11/m(2)), and high thermal performance. The development of polymer materials for this technology will be a key to early commercial success.

  5. Functional coating of liposomes using a folate– polymer conjugate to target folate receptors

    PubMed Central

    Watanabe, Kazuo; Kaneko, Makoto; Maitani, Yoshie

    2012-01-01

    Folate-polymer-coated liposomes were developed for targeted chemotherapy using doxorubicin (DXR) as a model drug. Folate-poly(L-lysine) (F–PLL) conjugates with a folate modification degree of 16.7 mol% on epsilon amino groups of PLL were synthesized. DXR-loaded anionic liposomes were coated with F–PLL, and the cellular association of F–PLL-coated liposomes was evaluated by flow cytometry, and confocal microscopy in human nasopharyngeal carcinoma KB cells overexpressing folate receptors (FRs), and human lung adenocarcinoma A549 cells [FR (−)]. The existence of a polymer layer on the surface of F–PLL-coated liposomes was confirmed by zeta potential analysis. The KB cellular association of F–PLL-coated liposomal DXR was increased compared with that of PLL-coated liposomes and was inhibited in the presence of free folic acid. Twofold higher cytotoxicity of F–PLL-coated liposomal DXR was observed compared with that of the PLL-coated liposomal DXR in KB cells, but not in A549 cells, suggesting the presence of FR-mediated endocytosis. These results indicated that folate-targeted liposomes were prepared successfully by coating the folate–polymer conjugate F–PLL. This novel preparation method of folate-targeted liposomes is expected to provide a powerful tool for the development of a folate-targeting drug nanodevice as coating with ligand–polymer conjugates can be applicable to many kinds of particles, as well as to lipid-based particles. PMID:22888227

  6. Conjugated Microporous Polymer Nanosheets for Overall Water Splitting Using Visible Light.

    PubMed

    Wang, Lei; Wan, Yangyang; Ding, Yanjun; Wu, Sikai; Zhang, Ying; Zhang, Xinlei; Zhang, Guoqing; Xiong, Yujie; Wu, Xiaojun; Yang, Jinlong; Xu, Hangxun

    2017-08-18

    Direct water splitting into H2 and O2 using photocatalysts by harnessing sunlight is very appealing to produce storable chemical fuels. Conjugated polymers, which have tunable molecular structures and optoelectronic properties, are promising alternatives to inorganic semiconductors for water splitting. Unfortunately, conjugated polymers that are able to efficiently split pure water under visible light (400 nm) via a four-electron pathway have not been previously reported. This study demonstrates that 1,3-diyne-linked conjugated microporous polymer nanosheets (CMPNs) prepared by oxidative coupling of terminal alkynes such as 1,3,5-tris-(4-ethynylphenyl)-benzene (TEPB) and 1,3,5-triethynylbenzene (TEB) can act as highly efficient photocatalysts for splitting pure water (pH ≈ 7) into stoichiometric amounts of H2 and O2 under visible light. The apparent quantum efficiencies at 420 nm are 10.3% and 7.6% for CMPNs synthesized from TEPB and TEB, respectively; the measured solar-to-hydrogen conversion efficiency using the full solar spectrum can reach 0.6%, surpassing photosynthetic plants in converting solar energy to biomass (globally average ≈0.10%). First-principles calculations reveal that photocatalytic H2 and O2 evolution reactions are energetically feasible for CMPNs under visible light irradiation. The findings suggest that organic polymers hold great potential for stable and scalable solar-fuel generation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Versatile solution for growing thin films of conducting polymers

    PubMed Central

    D’Arcy, Julio M.; Tran, Henry D.; Tung, Vincent C.; Tucker-Schwartz, Alexander K.; Wong, Rain P.; Yang, Yang; Kaner, Richard B.

    2010-01-01

    The method employed for depositing nanostructures of conducting polymers dictates potential uses in a variety of applications such as organic solar cells, light-emitting diodes, electrochromics, and sensors. A simple and scalable film fabrication technique that allows reproducible control of thickness, and morphological homogeneity at the nanoscale, is an attractive option for industrial applications. Here we demonstrate that under the proper conditions of volume, doping, and polymer concentration, films consisting of monolayers of conducting polymer nanofibers such as polyaniline, polythiophene, and poly(3-hexylthiophene) can be produced in a matter of seconds. A thermodynamically driven solution-based process leads to the growth of transparent thin films of interfacially adsorbed nanofibers. High quality transparent thin films are deposited at ambient conditions on virtually any substrate. This inexpensive process uses solutions that are recyclable and affords a new technique in the field of conducting polymers for coating large substrate areas. PMID:21041676

  8. Dispersing nanoparticles in a polymer film via solvent evaporation

    SciTech Connect

    Cheng, Shengfeng; Grest, Gary S.

    2016-05-19

    Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier to prevent the NPs from moving to the interface. Furthermore, our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.

  9. Dispersing nanoparticles in a polymer film via solvent evaporation

    SciTech Connect

    Cheng, Shengfeng; Grest, Gary S.

    2016-05-19

    Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier to prevent the NPs from moving to the interface. Furthermore, our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.

  10. Dispersing nanoparticles in a polymer film via solvent evaporation

    DOE PAGES

    Cheng, Shengfeng; Grest, Gary S.

    2016-05-19

    Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier tomore » prevent the NPs from moving to the interface. Furthermore, our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.« less

  11. Continuous production of functionalized polymer particles employing the phase separation in polymer blend films.

    PubMed

    Park, ChooJin; Hyun, Dong Choon; Lim, Min-Cheol; Kim, Su-Jeong; Kim, Young-Rok; Paik, Hyun-Jong; Jeong, Unyong

    2011-08-17

    This study reports a continuous prepartion of spherical or hemispherical polymer particles simply utilizing the phase separation in polymer blend films during the coating process. We took an advantage of the strong phase separation between a water-soluble crystalline polymer as a matrix and hydrophobic polymers as minor components. We demonstrated the prepartion of water-soluble polystyrene (PS) particles, nitrilotriacetic acid (NTA)-functionalized PS particles for protein separation, and semiconducting poly(3-hexylthiophene) (P3HT) particles. The sizes of the particles could be controlled by adjusting the film thickness and weight fraction of the minor component polymers in the blend film. It provides a simple facile way to prepare polymer particles in a continous process. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Atomic-force microscopy of submicron films of electroactive polymer

    NASA Astrophysics Data System (ADS)

    Karamov, D. D.; Kornilov, V. M.; Lachinov, A. N.; Kraikin, V. A.; Ionova, I. A.

    2016-07-01

    Atomic-force microscopy is used to study the supramolecular structure of submicron films of electroactive thermally stable polymer (polydiphenylenephthalide (PDP)). It has been demonstrated that PDP films produced using centrifuging are solid homogeneous films with thicknesses down to several nanometers, which correspond to two or three monomolecular layers. The film volume is structurized at thicknesses greater than 100 nm. The study of the rheological properties of solutions used for film production yields a crossover point that separates the domains of strongly diluted and semidiluted solutions. A transition from the globular structure to the associate structure is observed in films that are produced using solutions with a boundary concentration. A model of the formation of polymer film that involves the presence of associates in the original solution is discussed.

  13. Narrow Gap, High Mobility, and Stable Pi Conjugated Polymers

    DTIC Science & Technology

    2012-09-20

    applications and other devices of interest to the Air Force with a special focus on photodetectors (especially in the near infrared), solar cells , and...to be used as the active polymer in PCBM based solar cells . 6 Simplifying our chemistry, we have developed Stille coupling polymerization...weight illustrated in Table 1, such as the Mn = 30.5 kDa (red) and 35.1 kDa (blue) prepared via the Stille method provided effective solar cell

  14. Novel enzyme-polymer conjugates for biotechnological applications

    PubMed Central

    Romero, Oscar; Rivero, Cintia W.; Guisan, Jose M.

    2013-01-01

    In the present research, a rapid, simple and efficient chemoselective method for the site-directed incorporation of tailor-made polymers into protein to create biocatalysts with excellent properties for pharmaceutical industrial purpose has been performed. First we focused on the protein engineering of the Geobacillus thermocatenulatus lipase 2 (BTL2) to replace the two cysteines (Cys65, Cys296) in the wild type enzyme (BTL-WT) by two serines. Then, by similar mode, a unique cysteine was introduced in the lid area of the protein. For the site-directed polymer incorporation, a set of different tailor-made thiol-ionic-polymers were synthesized and the protein cysteine was previously activated with 2,2-dithiodipyridine (2-PDS) to allow the disulfide exchange. The protected BTL variants were specifically modified with the different polymers in excellent yields, creating a small library of new biocatalysts. Different and important changes in the catalytic properties, possible caused by structural changes in the lid region, were observed. The different modified biocatalysts were tested in the synthesis of intermediates of antiviral and antitumor drugs, like nucleoside analogues and derivatives of phenylglutaric acid. In the hydrolysis of per-acetylated thymidine, the best biocatalyst was the BTL*-193-DextCOOH , where the activity was increased in 3-fold and the regioselectivity was improved, reaching a yield of 92% of 3’-O-acetyl-thymidine. In the case of the asymmetric hydrolysis of dimethyl phenylglutarate, the best result was found with BTL*-193-DextNH2-6000, where the enzyme activity was increased more than 5-fold and the enantiomeric excess was >99%. PMID:23638362

  15. Measurements of Photo-induced Changes in Conjugated Polymers

    DOE R&D Accomplishments Database

    Seager, C. H.; Sinclair, M. B.; Mc Branch, D.; Heeger, A. J.; Baker, G. L.

    1991-01-01

    We have used the highly sensitive technique of Photothermal Deflection Spectroscopy (PDS) to measure changes in the infrared absorption spectra of MEHPPV, P3HT and Polydiacetylene-4BCMU induced by pumping these polymers with light above the {pi} - {pi}* transition energy. In contrast to previous chopped light transmission measurements of these effects, the PDS technique can directly measure the buildup or decay of the absorption coefficient, {alpha}, on the time scale of second to days. In the case of MEHPPV we observe that the time scale of seconds to days. In the case of MEHPPV we observe that above-gap light causes the appearance of a broad infrared peak in {alpha}, which continues to grow-in hours after the pump light is first applied. For this polymer the general shape of the absorption spectra in the unpumped state mimics the photo-induced changes, suggesting that remnant photo-induced states determine the maximum transparency observed under normal experimental conditions. For P3HT and to a lesser extent, MEHPPV, we also observe irreversible photo-induced absorption components which we tentatively identify with photo-induced oxidation of the polymer matrix.

  16. Electrochemical synthesis of Sm2O3 nanoparticles: Application in conductive polymer composite films for supercapacitors.

    PubMed

    Mohammad Shiri, Hamid; Ehsani, Ali; Jalali Khales, Mina

    2017-11-01

    A novel electrosynthetic method was introduced to synthesize of Sm2O3 nanoparticles and furthermore, for improving the electrochemical performance of conductive polymer, hybrid POAP/Sm2O3 films have then been fabricated by POAP electropolymerization in the presence of Sm2O3 nanoparticles as active electrodes for electrochemical supercapacitors. The structure, morphology, chemical composition of Sm2O3 nanoparticles was examined. Surface and electrochemical analyses have been used for characterization of Sm2O3 and POAP/Sm2O3 composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. The supercapacity behavior of the composite film was attributed to the (i) high active surface area of the composite, (ii) charge transfer along the polymer chain due to the conjugation form of the polymer and finally (iii) synergism effect between conductive polymer and Sm2O3 nanoparticles. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Fluorine substituted conjugated polymer of medium band gap yields 7% efficiency in polymer-fullerene solar cells.

    PubMed

    Price, Samuel C; Stuart, Andrew C; Yang, Liqiang; Zhou, Huaxing; You, Wei

    2011-03-30

    Recent research advances on conjugated polymers for photovoltaic devices have focused on creating low band gap materials, but a suitable band gap is only one of many performance criteria required for a successful conjugated polymer. This work focuses on the design of two medium band gap (~2.0 eV) copolymers for use in photovoltaic cells which are designed to possess a high hole mobility and low highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. The resulting fluorinated polymer PBnDT-FTAZ exhibits efficiencies above 7% when blended with [6,6]-phenyl C(61)-butyric acid methyl ester in a typical bulk heterojunction, and efficiencies above 6% are still maintained at an active layer thicknesses of 1 μm. PBnDT-FTAZ outperforms poly(3-hexylthiophene), the current medium band gap polymer of choice, and thus is a viable candidate for use in highly efficient tandem cells. PBnDT-FTAZ also highlights other performance criteria which contribute to high photovoltaic efficiency, besides a low band gap.

  18. Fluorine Substituted Conjugated Polymer of Medium Band Gap Yields 7% Efficiency in Polymer-Fullerene Solar Cells

    SciTech Connect

    Price, Samuel C.; Stuart, Andrew C.; Yang, Liqiang; Zhou, Huaxing; You, Wei

    2011-03-04

    Recent research advances on conjugated polymers for photovoltaic devices have focused on creating low band gap materials, but a suitable band gap is only one of many performance criteria required for a successful conjugated polymer. This work focuses on the design of two medium band gap (~2.0 eV) copolymers for use in photovoltaic cells which are designed to possess a high hole mobility and low highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. The resulting fluorinated polymer PBnDT-FTAZ exhibits efficiencies above 7% when blended with [6,6]-phenyl C61-butyric acid methyl ester in a typical bulk heterojunction, and efficiencies above 6% are still maintained at an active layer thicknesses of 1 μm. PBnDT-FTAZ outperforms poly(3-hexylthiophene), the current medium band gap polymer of choice, and thus is a viable candidate for use in highly efficient tandem cells. PBnDT-FTAZ also highlights other performance criteria which contribute to high photovoltaic efficiency, besides a low band gap.

  19. Fluorine Substituted Conjugated Polymer of Medium Band Gap Yields 7% Efficiency in Polymer-Fullerene Solar Cells

    SciTech Connect

    Price, Samuel C.; Stuart, Andrew C.; Yang, Liqiang; Zhou, Huaxing; You, Wei

    2011-03-30

    Recent research advances on conjugated polymers for photovoltaic devices have focused on creating low band gap materials, but a suitable band gap is only one of many performance criteria required for a successful conjugated polymer. This work focuses on the design of two medium band gap (~2.0 eV) copolymers for use in photovoltaic cells which are designed to possess a high hole mobility and low highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. The resulting fluorinated polymer PBnDT-FTAZ exhibits efficiencies above 7% when blended with [6,6]-phenyl C{sub 61}-butyric acid methyl ester in a typical bulk heterojunction, and efficiencies above 6% are still maintained at an active layer thicknesses of 1 μm. PBnDT-FTAZ outperforms poly(3-hexylthiophene), the current medium band gap polymer of choice, and thus is a viable candidate for use in highly efficient tandem cells. PBnDT-FTAZ also highlights other performance criteria which contribute to high photovoltaic efficiency, besides a low band gap.

  20. Confinement enhances dispersion in nanoparticle-polymer blend films.

    PubMed

    Chandran, Sivasurender; Begam, Nafisa; Padmanabhan, Venkat; Basu, J K

    2014-05-08

    Polymer nanocomposites constitute an important class of materials whose properties depend on the state of dispersion of the nanoparticles in the polymer matrix. Here we report the first observations of confinement-induced enhancement of dispersion in nanoparticle-polymer blend films. Systematic variation in the dispersion of nanoparticles with confinement for various compositions and matrix polymer chain dimensions has been observed. For fixed composition, strong reduction in glass transition temperature, Tg, is observed with decreasing blend-film thickness. The enhanced dispersion occurs without altering the polymer-particle interactions and seems to be driven by enhanced matrix-chain orientation propensity and a tendency to minimize the density gradients within the matrix. This implies the existence of two different mechanisms in polymer nanocomposites, which determines their state of dispersion and glass transition.

  1. Engineering curvature in graphene ribbons using ultrathin polymer films.

    PubMed

    Li, Chunyu; Koslowski, Marisol; Strachan, Alejandro

    2014-12-10

    We propose a method to induce curvature in graphene nanoribbons in a controlled manner using an ultrathin thermoset polymer in a bimaterial strip setup and test it via molecular dynamics (MD) simulations. Continuum mechanics shows that curvature develops to release the residual stress caused by the chemical and thermal shrinkage of the polymer during processing and that this curvature increases with decreasing film thickness; however, significant deformation is only achieved for ultrathin polymer films. Quite surprisingly, explicit MD simulations of the curing and annealing processes show that the predicted trend not just continues down to film thicknesses of 1-2 nm but that the curvature development is enhanced significantly in such ultrathin films due to surface tension effects. This combination of effects leads to very large curvatures of over 0.14 nm(-1) that can be tuned via film thickness. This provides a new avenue to engineer curvature and, thus, electromagnetic properties of graphene.

  2. Rapid synthesis of flexible conductive polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Blattmann, C. O.; Sotiriou, G. A.; Pratsinis, S. E.

    2015-03-01

    Polymer nanocomposite films with nanoparticle-specific properties are sought out in novel functional materials and miniaturized devices for electronic and biomedical applications. Sensors, capacitors, actuators, displays, circuit boards, solar cells, electromagnetic shields and medical electrodes rely on flexible, electrically conductive layers or films. Scalable synthesis of such nanocomposite films, however, remains a challenge. Here, flame aerosol deposition of metallic nanosliver onto bare or polymer-coated glass substrates followed by polymer spin-coating on them leads to rapid synthesis of flexible, free-standing, electrically conductive nanocomposite films. Their electrical conductivity is determined during their preparation and depends on substrate composition and nanosilver deposition duration. Accordingly, thin (<500 nm) and flexible nanocomposite films are made having conductivity equivalent to metals (e.g. 5 × 104 S cm-1), even during repetitive bending.

  3. Polymer Wall Formation Using Liquid-Crystal/Polymer Phase Separation Induced on Patterned Polyimide Films

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal phase separation of an LC/polystyrene solution between substrates with polyimide films etched by short-wavelength ultraviolet irradiation using a photomask. The LC wetting difference between the polyimide and substrate surfaces caused the coalescence of growing LC droplets on patterned polyimide films with the progress of phase separation. Consequently, polymer walls were formed on substrate surface areas without polyimide films. The shape of the polymer wall formed became sharp with the use of rubbed polyimide films because the nucleation of growing LC droplets concentrated on the patterned polyimide films. It is thought that the increase in the alignment order of LC molecules in the solution near the rubbed polyimide films promotes the formation of LC molecular aggregation, which becomes the growth nuclei of LC droplets.

  4. Study of (Cyclic Peptide)-Polymer Conjugate Assemblies by Small-Angle Neutron Scattering.

    PubMed

    Koh, Ming Liang; FitzGerald, Paul A; Warr, Gregory G; Jolliffe, Katrina A; Perrier, Sébastien

    2016-12-19

    We present a fundamental study into the self-assembly of (cyclic peptide)-polymer conjugates as a versatile supramolecular motif to engineer nanotubes with defined structure and dimensions, as characterised in solution using small-angle neutron scattering (SANS). This work demonstrates the ability of the grafted polymer to stabilise and/or promote the formation of unaggregated nanotubes by the direct comparison to the unconjugated cyclic peptide precursor. This ideal case permitted a further study into the growth mechanism of self-assembling cyclic peptides, allowing an estimation of the cooperativity. Furthermore, we show the dependency of the nanostructure on the polymer and peptide chemical functionality in solvent mixtures that vary in the ability to compete with the intermolecular associations between cyclic peptides and ability to solvate the polymer shell. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Single particle and ensemble spectroscopy of conjugated polymer nanoparticles and their development for photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Grimland, Jennifer L.

    Energy transport in conjugated polymers is the combination of energy transfer and exciton diffusion. There is considerable ongoing research in this field, converging to develop better organic photovoltaics, polymer light emitting diodes (PLEDs) and organic solar cells, to name a few. One way these phenomena can be explored is by doing solution dependent studies on conjugated polymer nanoparticles. With experiments on CP dots in an aqueous solution and the addition of a water miscible organic solvent in varying concentrations, dynamics occurring in the folding process can be better understood, and also exciton and fluorescence quenching properties can be extracted as a function of nanoparticle collapse. Steady state and time resolved fluorescence measurements were taken for two types of CP dots in bulk solution under varying solvent environments, including quantum yield, photobleaching and reversible photobleaching. The time-domain technique of time-correlated single photon counting (TCSPC) was used to determine excited state lifetimes and fluorescent decay traces. Simulating the TCSPC data provides insight on the relative number of quenchers that are observed by the polymer in each environment. In addition, single molecule fluorescence spectroscopy measurements were done on CP dots under varying solvent vapor atmospheres. Using the phenomenon of energy transfer, we have proven that doping the singlet oxygen photosensitizer tetraphenylporphyrin (TPP) into our conjugated polymer nanoparticles acts as an efficient and powerful photosensitizer for photodynamic therapy. The nanoparticles exhibit highly efficient collection of excitation light due to the large excitation cross-section of the polymer. A quantum efficiency of 0.5 was determined. Extraordinarily large cross-sections for two-photon absorption were found which is promising for near infrared multiphoton photodynamic therapy, and gel electrophoresis of DNA after irradiation in the presence of CP dots indicated

  6. Stress effects in prism coupling measurements of thin polymer films

    NASA Astrophysics Data System (ADS)

    Agan, S.; Ay, F.; Kocabas, A.; Aydinli, A.

    2005-02-01

    Due to the increasingly important role of some polymers in optical waveguide technologies, precise measurement of their optical properties has become important. Typically, prism coupling to slab waveguides made of materials of interest is used to measure the relevant optical parameters. However, such measurements are often complicated by the softness of the polymer films when stress is applied to the prism to couple light into the waveguides. In this work, we have investigated the optical properties of three different polymers, polystyrene (PS), polymethyl-methacrylate (PMMA), and benzocyclobutane (BCB). For the first time, the dependence of the refractive index, film thickness, and birefringence on applied stress in these thin polymer films was determined by means of the prism coupling technique. Both symmetric trapezoid shaped and right-angle prisms were used to couple the light into the waveguides. It was found that trapezoid shaped prism coupling gives better results in these thin polymer films. The refractive index of PMMA was found to be in the range of 1.4869 up to 1.4876 for both TE and TM polarizations under the applied force, which causes a small decrease in the film thickness of up to 0.06 μm. PMMA waveguide films were found not to be birefringent. In contrast, both BCB and PS films exhibit birefringence albeit of opposing signs.

  7. Precise Side-Chain Engineering of Thienylenevinylene-Benzotriazole-Based Conjugated Polymers with Coplanar Backbone for Organic Field Effect Transistors and CMOS-like Inverters.

    PubMed

    Lee, Min-Hye; Kim, Juhwan; Kang, Minji; Kim, Jihong; Kang, Boseok; Hwang, Hansu; Cho, Kilwon; Kim, Dong-Yu

    2017-01-25

    Two donor-acceptor (D-A) alternating conjugated polymers based on thienylenevinylene-benzotriazole (TV-BTz), PTV6B with a linear side chain and PTVEhB with a branched side chain, were synthesized and characterized for organic field effect transistors (OFETs) and complementary metal-oxide-semiconductor (CMOS)-like inverters. According to density functional theory (DFT), polymers based on TV-BTz exhibit a coplanar and rigid structure with no significant twists, which could cause to an increase in charge-carrier mobility in OFETs. Alternating alkyl side chains of the polymers impacted neither the band gap nor the energy level. However, it significantly affected the morphology and crystallinity when the polymer films were thermally annealed. To investigate the effect of thermal annealing on the morphology and crystallinity, we characterized the polymer films using atomic force microscopy (AFM) and 2D-grazing incidence X-ray diffraction (2D-GIWAXD). Fibrillary morphologies with larger domains and increased crystallinity were observed in the polymer films after thermal annealing. These polymers exhibited improved charge-carrier mobilities in annealed films at 200 °C and demonstrated optimal OFET device performance with p-type transport characteristics with charge-carrier mobilities of 1.51 cm(2)/(V s) (PTV6B) and 2.58 cm(2)/(V s) (PTVEhB). Furthermore, CMOS-like inorganic (ZnO)-organic (PTVEhB) hybrid bilayer inverter showed that the inverting voltage (Vinv) was positioned near the ideal switching point at half (1/2) of supplied voltage (VDD) due to fairly balanced p- and n-channels.

  8. Adhesion of metals to spin-coated fluorocarbon polymer films

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Kil; Chang, Chin-An; Schrott, A. G.

    1990-01-01

    Adhesion between metals and fluorocarbon polymer films has been studied for Cu, Cr, Ti, Al, and Au on polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films. Polymer films were applied on the Cr/SiO2 /Si substrate by spinning the aqueous dispersions of the polymer resin particles, followed by thermal curing. Strips of different metals were deposited on the polymers, and adhesion was measured at 90° peel test. The peel strengths were invariably higher for the metals on FEP than those of the corresponding metals on PTFE. Among the metals, Ti showed the highest peel strength for both polymers, followed by Cr and Al, with Cu and Au being the lowest. The peel strengths of Ti, Cr, and Cu on FEP are 85, 45, and 12 g/mm, respectively, and the corresponding ones on PTFE are 23, 5, and 2 g/mm, respectively. X-ray photoelectron spectroscopic analysis shows that the metal-polymer bonding involves the metal-carbon interactions. The strongest interaction is observed for Ti with the polymers, forming Ti carbidelike bonds. Cr also shows strong interaction with the two polymers, but to a lesser degree compared with Ti. Only a weak bonding is shown for Cu. The difference in peel strengths among the metals shows a correlation with the difference in electronegativities between the metals and carbon. Little contribution to the observed peel strengths is seen from the surface morphological analysis of the untreated polymers.

  9. Fracture and fatigue of ultrathin nanoporous polymer films

    NASA Astrophysics Data System (ADS)

    Kearney, Andrew V.

    Nanoporous polymer layers are being considered for a range of emerging nanoscale applications, from low permittivity materials for interlayer dielectrics in microelectronics and anti-reflective coatings in optical technologies, to biosensors and size-selective membranes for biological applications. Polymer thin films have inherently low elastic modulus, strength and hardness, but exhibit fracture properties that are higher than those reported for glass, ceramic, and even some metal layers. However, constraint of a ductile polymer between two elastic layers is expected to affect the local plasticity ahead of a crack tip and its contribution to the film adhesion with films below a micron in thickness. Additionally, nanoporosity would be expected to have a deleterious effect on mechanical properties, producing materials and layers that are structurally weaker than fully dense versions they replace. Therefore, the integration of these nanoporous polymer layer at nanometer thicknesses would present significantly processing and mechanical reliability challenges. In this dissertation, surprising evidence is presented that nanoporous polymer films exhibit increasing fracture energy with increasing porosity. Such behavior is in stark contrast to a wide range of reported behavior for porous solids. A ductile nano-void growth and coalescence fracture mechanics-based model is presented to rationalize the increase in fracture toughness of the voided polymer film. The model is shown to explain the behavior in terms of a specific scaling of the size of the pores with pore volume fraction. It is demonstrated that the pore size must increase with close to a linear dependence on the volume fraction in order to increase rather than decrease the fracture energy. Independent characterization of the pore size as a function of volume fraction is shown to confirm predictions made by the model. The fracture behavior of these constrained polymer films are also examined with film thickness

  10. Renewable cathode materials from biopolymer/conjugated polymer interpenetrating networks.

    PubMed

    Milczarek, Grzegorz; Inganäs, Olle

    2012-03-23

    Renewable and cheap materials in electrodes could meet the need for low-cost, intermittent electrical energy storage in a renewable energy system if sufficient charge density is obtained. Brown liquor, the waste product from paper processing, contains lignin derivatives. Polymer cathodes can be prepared by electrochemical oxidation of pyrrole to polypyrrole in solutions of lignin derivatives. The quinone group in lignin is used for electron and proton storage and exchange during redox cycling, thus combining charge storage in lignin and polypyrrole in an interpenetrating polypyrrole/lignin composite.

  11. Renewable Cathode Materials from Biopolymer/Conjugated Polymer Interpenetrating Networks

    NASA Astrophysics Data System (ADS)

    Milczarek, Grzegorz; Inganäs, Olle

    2012-03-01

    Renewable and cheap materials in electrodes could meet the need for low-cost, intermittent electrical energy storage in a renewable energy system if sufficient charge density is obtained. Brown liquor, the waste product from paper processing, contains lignin derivatives. Polymer cathodes can be prepared by electrochemical oxidation of pyrrole to polypyrrole in solutions of lignin derivatives. The quinone group in lignin is used for electron and proton storage and exchange during redox cycling, thus combining charge storage in lignin and polypyrrole in an interpenetrating polypyrrole/lignin composite.

  12. High-mobility n-type conjugated polymers based on electron-deficient tetraazabenzodifluoranthene diimide for organic electronics.

    PubMed

    Li, Haiyan; Kim, Felix Sunjoo; Ren, Guoqiang; Jenekhe, Samson A

    2013-10-09

    High-mobility p-type and ambipolar conjugated polymers have been widely reported. However, high-mobility n-type conjugated polymers are still rare. Herein we present poly(tetraazabenzodifluoranthene diimide)s, PBFI-T and PBFI-BT, which exhibit a novel two-dimensional (2D) π-conjugation along the main chain and in the lateral direction, leading to high-mobility unipolar n-channel transport in field-effect transistors. The n-type polymers exhibit electron mobilities of up to 0.30 cm(2)/(V s), which is among the highest values for unipolar n-type conjugated polymers. Complementary inverters incorporating n-channel PBFI-T transistors produced nearly perfect switching characteristics with a high gain of 107.

  13. Targeted conjugation of breast anticancer drug tamoxifen and its metabolites with synthetic polymers.

    PubMed

    Sanyakamdhorn, S; Agudelo, D; Bekale, L; Tajmir-Riahi, H A

    2016-09-01

    Conjugation of antitumor drug tamoxifen and its metabolites, 4-hydroxytamxifen and ednoxifen with synthetic polymers poly(ethylene glycol) (PEG), methoxypoly (ethylene glycol) polyamidoamine (mPEG-PAMAM-G3) and polyamidoamine (PAMAM-G4) dendrimers was studied in aqueous solution at pH 7.4. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize the drug binding process to synthetic polymers. Structural analysis showed that drug-polymer binding occurs via both H-bonding and hydrophobic contacts. The order of binding is PAMAM-G4>mPEG-PAMAM-G3>PEG-6000 with 4-hydroxttamoxifen forming more stable conjugate than tamoxifen and endoxifen. Transmission electron microscopy showed significant changes in carrier morphology with major changes in the shape of the polymer aggregate as drug encapsulation occurred. Modeling also showed that drug is located in the surface and in the internal cavities of PAMAM with the free binding energy of -3.79 for tamoxifen, -3.70 for 4-hydroxytamoxifen and -3.69kcal/mol for endoxifen, indicating of spontaneous drug-polymer interaction at room temperature.

  14. Effect of interchain coupling on the excited polaron in conjugated polymers

    NASA Astrophysics Data System (ADS)

    Li, Xiao-xue; Chen, Gang

    2017-02-01

    Based on the one-dimensional extended Su-Schrieffer-Heeger model, we theoretically investigate the effect of interchain coupling on the formation and polarization of the single-excited state of polaron in conjugated polymers. It is found that there exists a turnover value of the coupling strength, over which the excited polaron could not be formed in either of the two coupled chains. Instead, a polaron-like particle is localized at the center of each chain. In addition, we also find that the reverse polarization of the excited polaron could be enhanced for some cases in polymer when the interchain coupling becomes strong until it exceeds the critical value.

  15. Plasmon-enhanced conjugated polymer luminescence using silver nanoparticles and sequentially adsorbed polyelectrolyte spacers

    NASA Astrophysics Data System (ADS)

    Pan, Shanlin; Rothberg, Lewis J.; Nolte, Adam J.; Rubner, Michael F.; Gorodetskaya, Irina; Swager, Timothy M.

    2005-08-01

    Up to fifty fold increases in water soluble conjugated phenylenevinylene polymer fluorescence are observed when these polymers are adsorbed onto silver nanoparticle treated surfaces with layer-by-layer deposited polyelectrolyte spacers. The silver particle density and spacer thickness dependence of the enhancement are investigated. Using absorption, fluorescence, fluorescence excitation and transient photoluminescence measurments, we infer the relative importance of absorption and emissive rate increases in explaining the observed enhancement. Large blue shifts due to interactions of the molecular excited states with the silver particle plasmons are observed.

  16. Theory of Exciton Migration and Field-Induced Dissociation in Conjugated Polymers

    NASA Astrophysics Data System (ADS)

    Vissenberg, M. C. J. M.; de Jong, M. J. M.

    1996-12-01

    The interplay of migration, recombination, and dissociation of excitons in disordered media is studied theoretically in the low temperature regime. An exact expression for the photoluminescence spectrum is obtained. The theory is applied to describe the electric field-induced photoluminescence-quenching experiments by Kersting et al. [Phys. Rev. Lett. 73, 1440 (1994)] and Deussen et al. [Synth. Met. 73, 123 (1995)] on conjugated polymer systems. Good agreement with experiment is obtained using an on-chain dissociation mechanism, which implies a separation of the electron-hole pair along the polymer chain.

  17. Oxygen Radicals in Influenza-Induced Pathogenesis and Treatment with Pyran Polymer-Conjugated SOD

    NASA Astrophysics Data System (ADS)

    Oda, Tatsuya; Akaike, Takaaki; Hamamoto, Takayoshi; Suzuki, Fujio; Hirano, Takashi; Maeda, Hiroshi

    1989-05-01

    The pathogenicity of influenza virus infection in the mice involves, at least in part, overreaction of the immune responses of the host rather than a direct effect of virus multiplication. Xanthine oxidase, which is responsible for the generation of oxygen free radicals, was elevated in serum and lung tissue of mice infected with influenza virus. To test the theory that oxygen-free radicals are involved in path