Macromolecular Chemistry and Physics
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Special Series: New Frontiers in Functional Polymers
In this series, Macromol. Chem. Phys. publishes in an on-going fashion invited articles by leading researchers in the broad field of functional polymers. After the first two parts on polymers from triple-bond building blocks and luminogenic polymers, guest-edited by Ben Zhong Tang, the focus now shifts towards polymers for organic electronics (guest-editors Wai-Yeung Wong and Ben Zhong Tang).
Improvement in Power Conversion Efficiency and Performance of P3HT/PCBM Solar Cells Using Dithiafulvalene-Based π-Conjugated Oligomers
Po-Chih Yang,* Hua-Wen Wen, Cheng-Chieh Huang, Zheng-Huie Yang, Hung-Lun Liao
Three dithiafulvalene (DTF)-based oligomers as a dopant for poly(3-hexylthiophene) P3HT/[6,6]-phenyl-C61butyric acid methyl ester (PCBM) solar cells are developed by incorporating a π-conjugated DTF unit that serves as an electron-rich donor in the main chain. Using poly[2-(9H-fluoren-9-ylidene)-4,5-bis(hexylthio)-1,3-dithiole-ran-(2,1,3-benzothiadiazole)] (PTBT) as a dopant in bulk-heterojunction (BHJ) solar cells improves the charge-carrier mobilities, the open-circuit voltage, and the stability of the devices.
Macromol. Chem. Phys., DOI: 10.1002/macp.201400307
Synthesis and Photovoltaic Properties of New Multifused Anthradithiophene-Based Narrow-Bandgap D-A CopolymersQi-Da Liu, Rui-Xiang Peng, Shao-Jie Chen, Ling Ai, She-Yu Wang, Zhi-Yang Liu and Zi-Yi Ge*
Three structurally novel anthradithiophene-based donor-acceptor (D-A) copolymers are synthesized and used to fabricate polymer solar cells. Under identical post-processing conditions, the power conversion efficiency (PCE) of inverted polymer solar cell (PSC) devices is over two times higher than in corresponding conventional devices. The improved efficiencies for inverted devices are due to the close energy alignment between the work function of the MoO3 and the highest occupied molecular orbital (HOMO) energy levels of the copolymers.
Macromol. Chem. Phys., DOI: 10.1002/macp.201400119
Optical and Electroluminescent Studies of White-Light-Emitting Copolymers Based on Poly(9,9-dioctylfluorene) and Fluorenone DerivativesHua Wang,* Junli Yang, Jing Sun, Yang Xu, Yuling Wu, Qingcheng Dong, Wai-Yeung Wong,* Yuying Hao, Xinwen Zhang and Hua Li
A class of white-light-emitting copolymers based on polyfluorene is synthesized, in which 2,7-di-(2-thienyl)-9-fluorenone (DTFO) is introduced as the orange-emitting unit. It can be used in white-light organic light-emitting diodes with a single light-emitting layer. The color of the white light can be tuned by changing the content of DTFO.
Macromol. Chem. Phys., DOI: 10.1002/macp.201400070
4,5-Ethylene-2,7-Carbazole-Based Medium-Bandgap Conjugated Polymers with Low-Lying HOMO Levels TowardJiangman Sun, Yongxiang Zhu, Xiaofeng Xu, Chen Zhang, Junwu Chen, Hongzheng Chen and Yong Cao
D-A conjugated polymers of 4,5-ethylene-2,7-dithienyl carbazole and 5,6-dialkoxy-2,1,3-benzothiadiazoles possess deep highest occupied molecular orbital (HOMO) levels around -5.45 eV and medium bandgaps of about 1.94 eV. Their polymer solar cells show a high Voc of 0.95 V and good power conversion efficiency (PCE) up to 5.91%, which is promising as a front cell for harvesting the shorter-wavelength band of solar radiation in a tandem solar cell.
Macromol. Chem. Phys., DOI: 10.1002/macp.201400001
Synthesis and Photovoltaic Properties of a D–A Copolymer Based on the 2,3-Di(5-hexylthiophen-2-yl)quinoxaline Acceptor Unit
Kun Wang, Zhi-Guo Zhang, Qiang Fu,* and Yongfang Li*
A new D–A copolymer, PBDT-DTQx, based on the 2,3-di(5-hexylthiophen-2-yl)quinoxaline (>DTQx) acceptor unit is designed and synthesized for application as a donor material in polymer solar cells (PSCs). The device based on PBDT-DTQx:PC70BM (1:2.5, w/w) with chloronaphthalene as a solvent additive displays a power conversion efficiency (PCE) of 3.15%. With methanol treatment, the PCE of the PSCs is further improved to 3.90%.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300793
Ordered Organic Nanostructures Fabricated from Anodic Alumina Oxide Templates for Organic Bulk-Heterojunction Photovoltaics
Hui Wu, Junliang Yang,* Shilin Cao, Liulian Huang and Lihui Chen
The anodic aluminum oxide (AAO) template technique is a versatile and fascinating method for producing ordered organic nanostructures with controllable properties, showing potential applications in the fabrication of solution-based ordered bulk-heterojunction organic photovoltaics with high performance.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300766
Synthesis and Photovoltaic Characterization of Dithieno[3,2-b:2',3'-d]thiophene-Derived Narrow-Bandgap PolymersEnwei Zhu, Bin Ni, Baofeng Zhao, Jiefeng Hai, Linyi Bian, Hongbin Wu, Weihua Tang*
Three dithieno[3,2-b:2',3'-d]thiophene-based narrow-bandgap polymers are developed. They have a bandgap of 1.75-1.87 eV. The best performing bulk-heterojunction (BHJ) solar cells contribute a power conversion efficiency of 0.73% by blending with (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM).
Macromol. Chem. Phys., DOI: 10.1002/macp.201300669
Near-Infrared Photovoltaic Performance of Conjugated Polymers Containing Thienoisoindigo Acceptor UnitsMakoto Karakawa*, Yoshio Aso*
NIR-absorbing donor-acceptor-type polymers containing the thienoisoindigo unit are synthesized. The UV-vis spectra of the polymers show features that extended up to 1200 nm in the NIR. The organic photovoltaic cells using the synthesized polymers show a photocurrent response in the NIR with power conversion efficiency up to 0.52% under AM 1.5 photo irradiation.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300426
Attempted Inversion of Semiconducting Features of Platinum Polyyne Polymers: A New Approach for All-Polymer Solar CellsYuping Yuan, Tsuyoshi Michinobu,* Jun Oguma, Takehito Kato and Kunihito Miyake
Formal cycloaddition–retro-electrocyclization reactions between platinum(II) polyyne polymers and tetracyanoethylene (TCNE) successfully lower the polymer energy levels. Application of these polymers to p-type semiconducting materials in bulk-heterojunction solar cells suggests that the p-type performance decreases by approximately 5 to 10 times. Moreover, when a TCNE-adducted polymer is employed as an n-type semiconducting material, the generation of weak photocurrent is achieved.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300245
Carbazole-Substituted Triphenylamine and Diketopyrrolopyrrole Alternating Copolymer for Photovoltaic Cells
Linyi Bian, Dong Yang, Liangming Yin, Jian Zhang* and Weihua Tang*
An alternating conjugated polymer (PTCDPP) of carbazole-substituted triarylamine and diketopyrrolopyrrole is prepared with a bandgap of 1.66 eV. By using 1,8-diiodooctane(DIO) (3% v/v) as a processing additive and annealing the active layer at 80 °C, the best performing device PTCDPP:PCBM (1:4, w/w) exhibits a power coversion efficiency of 2.65%.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300356
Novel Cyclopentadithiophene-Based D–A Copolymers for Organic Photovoltaic Cell ApplicationsFedor V. Drozdov, Ekaterina N. Myshkovskaya, Diana K. Susarova, Pavel A. Troshin, Olga D. Fominykh, Marina Yu. Balakina, Artem V. Bakirov, Maxim A. Shcherbina, Jinwoo Choi, Denis Tondelier, Mikhail I. Buzin, Sergei N. Chvalun, Abderrahim Yassar and Sergei A. Ponomarenko*
A series of donor–acceptor copolymers based on cyclopentadithiophene and dithienosilol are synthesized via the Suzuki coupling reaction and used in polymer solar cells. The influence of silicon versus carbon atoms on the light harvesting properties of the copolymers is estimated and the phase behavior of the copolymers with linear and branched alkyl side groups is compared.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300328
Synthesis and Photovoltaic Properties of a New Low-Bandgap Polymer Consisting of Benzodithiophene and Fluorinated Benzoselenadiazole UnitsSeung Ah Shin, Ji-Hoon Kim, Jong Baek Park, In-Nam Kang, Moo-Jin Park and Do-Hoon Hwang*
A donor–acceptor-type conjugated alternating copolymer (PBDT–DFBSe) consisting of benzodithiophene (BDT) and a fluorinated 2,1,3-benzoselenadiazole derivative (DFBSe) is synthesized. The optical, electrochemical, and photovoltaic properties of PBDT–DFBSe are compared with those of its non-fluorinated analog, PBDT–BSe, which is composed of BDT and 2,1,3-benzoselenadiazole (BSe). Bulk heterojunction organic photovoltaic cells are fabricated using the polymers.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300308
Synthesis and Photovoltaic Properties of D–A Copolymers Based on 11,12-Difluorodibenzo[a,c]phenazine Acceptor UnitKun Wang, Pei Jiang, Zhi-Guo Zhang, Qiang Fu* and Yongfang Li*
Four conjugated D-π-A copolymers based on 11,12-difluorodibenzo[a,c]phenazine as an acceptor unit are synthesized to investigate the effect of the side-chain nature and position on the photovoltaic performance of the conjugated polymers in polymer solar cells. The results indicate that side-chain engineering is very important for improving the photovoltaic performance of polymer donor materials.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300299
Advanced Functional Polymers for Increasing the Stability of Organic Photovoltaics
Eva Bundgaard, Martin Helgesen, Jon E. Carlé, Frederik C. Krebs, and Mikkel Jørgensen*
New polymers for organic photovoltaics are developed to increase their stability in devices, both with respect to photochemical and morphological degradation mechanisms. One solution is to incorporate labile side chains that can be split off by heat or light treatment during the production as shown in the figure.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300076
Benzo[1,2-b:4,5-b']dithiophene-alt-terthiophene Copolymers Containing Styryl-Triphenylamine Side Chains: Synthesis and Photovoltaic Performance Optimization with Fullerene Acceptors
Xitian Wang, Zhi-Guo Zhang,* Wenli Tang, Suling Shen, Guo Liu, Dan Chi, Yongfang Li, Jizheng Wang
A new copolymer is designed and synthesized, and the photovoltaic performance is optimized with fullerene acceptors. The energy loss and the increase in the observed open-circuit voltages are quantitatively explained by the up-shifted lowest unoccupied molecular level of indene-C60 bisadduct (ICBA) and the reduced saturation current in the blends.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300041
ZnII Bisterpyridine Metallopolymers: Improved Processability by the Introduction of Polymeric Side Chains
Andreas Wild, Anke Teichler, Christian von der Ehe, Andreas Winter, Martin D. Hager, Bing Yao, Baohua Zhang, Zhiyuan Xie, Wai-Yeung Wong,* Ulrich S. Schubert*
Tailoring of the optical and mechanical properties of bisterpyridine coordination polymers is enabled by the introduction of well-defined polymeric side chains. The resulting metallopolymers exhibit improved solubility and processability and can, therefore, easily be inkjet-printed. The photophysical properties of the so-produced homogeneous films are investigated and a proof-of-principle polymer light-emitting device can be constructed.
Macromol. Chem. Phys., DOI: 10.1002/macp.201300003
Morphology and Field-Effect Transistor Characteristics of Electrospun Nanofibers Prepared From Crystalline Poly(3-hexylthiophene) and Polyacrylate BlendsChih-Chieh Chou, Hung-Chin Wu, Chih-Jung Lin, Ebrahim Ghelichkhani, Wen-Chang Chen*
Nanofiber field-effect transistors (FETs) based on crystalline poly(3-hexylthiophene) (P3HT) and poly(stearyl acrylates) (PSA) or poly(n-lauryl acrylate) (PnLA) blends are fabricated via coaxial electrospinning (ES). The maximum FET mobility is obtained for P3HT/PSA (1:0.2) blends. The crystalline PSA promotes the larger crystallinity of P3HT in the ES nanofibers, which subsequently leads to the observation of higher mobility and improves the air stability.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200580
Thermochromic and Photovoltaic Properties of an Alternating Copolymer of Dithieno[3,2-b:2',3'-d]thiophene and Thieno[3,4-c]pyrrole-4,6-dioneZhao Li,* Patrick Malenfant, Ye Tao, Jianfu Ding*
A new alternating conjugated polymer, PDTTTPD, based on electron-rich dithieno[3,2-b:2',3'-d]thiophene (DTT) and electron-deficient thieno[3,4-c]pyrrole-4,6-dione (TPD) building block is designed and synthesized. PDTTTPD shows strong thermochromic effect in chlorobenzene solution and modest PCE of 2.1% in organic solar cell devices due to the steric hindrance induced twisting of the conjugated main chain. A general design rule is then suggested to control the main chain conformation of polymer materials for photovoltaic applications.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200468
Accessing New DPP-Based Copolymers by Direct Heteroarylation PolymerizationJean-Rémi Pouliot, Lauren G. Mercier, Samuel Caron, Mario Leclerc*
The direct heteroarylation polymerization methodology was adapted for the diketopyrrolopyrrole moiety, giving rise to copolymers that were difficult to obtain from standard Stille or Suzuki couplings. These new low-bandgap polymers proved to be efficient electron-transporting materials enabling possible applications in all-plastic solar cells.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200573
Screening of Film-Formation Qualities of Various Solvent Systems for π-Conjugated Polymers Via Combinatorial Inkjet PrintingAnke Teichler, Jolke Perelaer, Ulrich S. Schubert*
A systematical investigation of the relationships between the choice of solvent system and the film quality of inkjet printed π-conjugated polymer films is presented. A significant influence of the boiling points of the chosen main and co-solvents is observed, leading to the identification of new solvent systems that reveal improved film qualities.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200547
Recent Progress in Polymer White Light-Emitting Materials and DevicesChao Tang*, Xu-Dong Liu, Feng Liu, Xu-Liang Wang, Hui Xu, Wei Huang*
Polymer white light-emitting diodes (PWLEDs) are one of the most intensively researched topics in PLED. At present, there are two main methods to realize white emission in PLED. The one is to dope the host with different guests with different color, and the other is to prepare single white polymer by designing the molecular structure. Improving the performance of PWLED depends on the understanding of materials structure and properties, materials purification, and device engineering.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200305
Conformational Behavior of Conjugated Polymers With Oligo(phenylene vinylene) Side ChainsHelmuth Peeters, Guy Koeckelberghs*
Conjugated polymers with different oligo(phenylene vinylene) (OPV) side chains are prepared. The influence of the length of the OPV side chain and the placement of chiral substituents on the optical properties, the supramolecular structure, and the chiral expression is investigated.
Macromol. Chem. Phys., DOI: 10.1002/macp.201200584
Metal-Free and Metallated Polymers: Properties and Photovoltaic PerformanceA. Ng, C.-L. Ho, M. K. Fung, Y. C. Sun, S.-Y. Shao, Y.-Y. Fu, A. M. C. Ng, C. H. Li, W. K. Cheung, Y. H. Leung, A. B. Djurisic,* Q. Wang, Z. He, X. Wang, W.-K. Chan, Z.-Y. Xie,* J. A. Zapien, C. H. To, W.-Y. Wong*
Optical and photovoltaic properties of Pt-containing and metal-free polymers with similar structures are investigated. It is found that incorporation of metal results not only in an additional absorption band but also results in changes in the film morphology and phase separation, and hence a significant improvement in the photovoltaic performance.
Macromol. Chem. Phys., DOI: 10.1002/macp.201100686
Enhanced Performance for Polymer Solar Cells by Using Surfactant-Modified PEDOT:PSS as the Anode Buffer Layer
G. Fang, S. Wu, Z. Xie,* Y. Geng, L. Wang
A modified PEDOT:PSS is prepared by doping with a small amount of cationic surfactant of CTAB. XPS results show the insulating PSS enrichment on the top surface of the PEDOT:PSS layer is restrained by this doping. By using the CTAB-modified PEDOT:PSS instead of PEDOT:PSS as the anode buffer layer, the power conversion efficiency of the P3HT:PCBM bulk heterojunction solar cells is increased about 50% and an efficiency of 4.4% is achieved.
Macromol. Chem. Phys., DOI: 10.1002/macp.201100102
Anthraquinone-Imide-Based Dimers: Synthesis, Piezochromism, Liquid Crystalline and Near-Infrared Electrochromic PropertiesF. Chen, J. Zhang, X. Wan*
A series of anthraquinone-imide-based liquid crystalline dimers with different siloxane spacers present redox activities, exhibiting intense near-infrared absorption upon reduction to radical anionic states. External pressure responsive color changes are also observed and measured.
Macromol. Chem. Phys., DOI: 10.1002/macp.201100065
Synthesis and photovoltaic properties of a poly(2,7-carbazole) derivative based on dithienosilole and benzothiadiazoleJ. Zhou, X. Wan*, Y. Liu, F. Wang, G. Long, C. Li, Y. Chen*
A poly(2,7-carbazole) derivative with dithienosilole and benzothiadiazole is designed and synthesized via Stille polymerization. Due to the incorporated dithienosilole and carbazole moieties the polymer shows a broad absorption from 350 to 800 nm and a relatively low HOMO level. Applied in solar cell devices a power conversion efficiency of 1.65% is achieved for this polymer blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) when 1,8-diiodooctane is used as an additive.
Macromol. Chem. Phys., DOI: 10.1002/macp.201100060
New blue light emitting polymers for polymer LEDsH.-M. Shih, C.-J. Lin, S.-R. Tseng, C.-H. Lin, C.-S. Hsu*
Polymer light emitting diodes (PLED) are attracting great interest because of their potential applications in full-color flat panel displays and in solid-state lighting. Of the three elemental colors, the materials for blue light emission remain problematic. Polyfluorenes (PFs) show promise as blue light emitting polymers due to their high photoluminescence (PL) quantum efficiency, and good thermal and chemical stability. However, PFs exhibit poor electroluminescence and color stability, due to their intermolecular aggregation of the polymer backbones, and the keto effect. As it is known that device performance improvements are possible by the incorporation of dopants in the polymer chains, in this study new anthracene-based blue-light-emitting polymers, where the dopants are covalently bonded to the polymer chain, are synthesized via a palladium-catalyzed Suzuki Polymerization.
They have a high photoluminescence quantum yield as well as good electrochemical properties, resulting in stable color and enhanced device performance. The double-layer and multilayer devices fabricated exhibit good performance. These results are recently published as part of the ongoing series on Functional Polymers - Luminogenic Polymers in Macromolecular Chemistry and Physics.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000680
High-Mobility Conjugated Polymers Based on Fused-Thiophene Building BlocksYao Liu, Yunqi Liu,* Xiaowei Zhan*
Organic field-effect transistors (OFETs) are a promising cost-effective alternative to siliconbased field-effect transistors, and possess low-cost, light-weight, and flexibility advantages.
Conjugated polymers based on fused-thiophene building blocks have received considerable attention in the emerging field of organic electronics. In this review the most recent developments in conjugated polymers based on fused-thiophene rings for high-performance OFETs are summarized. The focus is on correlations of polymer chemical structures with properties, such as energy levels, filmforming property, film morphology, and OFET performance. This structure-property relationship analysis may guide rational structural design and evaluation of organic semiconductors. This article is additionally featured on MaterialsViews.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000677
Functionalization of Graphene Sheets by Polyacetylene: Convenient Synthesis and Enhanced Emission
X. Xu, Q. Luo, W. Lv, Y. Dong,* Y. Lin, Q. Yang,* A. Shen, D. Pang, J. Hu, J. Qin, Z. Li*
Taking advantage of nitrene chemistry, in particular the high reactivity, graphene moieties are successfully introduced into polyacetylenes to yield both the soluble and insoluble parts of polymer-graphene composites. Upon the attachment of graphene, the luminescence of the polyacetylenes is enhanced without affecting the electronic structure of graphene. These results are recently published as part of the ongoing series on Functional Polymers - Luminogenic Polymers in Macromolecular Chemistry and Physics.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000608
Ruthenium complexes incorporated into conjugated polymers for Dye-Sensitized Solar CellsH. T. Chan, C. S. K. Mak, A. B. Djurisic, W. K. Chan*
The synthesis of two ruthenium terpyridine complexes containing conjugated polymers is reported and their application as photosensitizers in dye-sensitized solar cells (DSSC) based on TiO2 nanoparticles and nanotubes was studied. The polymers were synthesized by the palladium-catalyzed coupling reaction between the ruthenium complex monomer and the fluorene-based comonomer. Functionalization with a carboxylic acid group strongly facilitated the anchorage of polymer dye molecules on the electrode surface. The power conversion efficiencies of the DSSCs sensitized with polymers functionalized with carboxylic groups were in the range between 0.12 and 0.13%. It was found that DSSCs fabricated from TiO2 nanoparticles and nanotubes substrates showed comparable performance.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000589
Liquid-Crystalline Conjugated PolymersL. Chen,* Y. Chen,* D. Zhou, F. Li, D. Zha, K. Yao
Introducing anisotropic properties into conjugated polymers by the incorporation of liquid crystals may provide an interesting path to develop novel electronic and photonic devices. In this feature article the authors present the effects of structural variations of the conjugated polymer backbone and the pendant terphenyl moieties on the properties of the liquid-crystalline conjugated polymers. The mesogenic and chromophoric terphenyl core endows the polymers with high photoluminescence, enantiotropic mesophases and induced circular dichroism.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000388
Highly Substituted Starburst Macromolecular SemiconductorsW.-Y. Lai,* D. Liu, W. Huang*
In order to combine the advantages of both uniformally structured oligomers and easily processable polymers the authors report a new strategy to synthezise π-conjugated organic semiconductors. Via a high yield microwave enhanced synthesis method for direct twelvefold Suzuki couplings a series of highly substituted twelve-armed macromolecules consisting of truxene, 9-phenylcarbazole and oligofluorene units were prepared. The resulting materials exhibited high purity, good monodispersity, and an extraordinary high molecular weight observed for a well-defined starburst conjugated molecule. Experiments to investigate the thermal, photophysical and electrochemical properties demonstrated the significance of constructing highly substituted starburst macromolecular structures on improving the amorphous properties and showed promising luminescence and electrochemical properties for the utilization of this class of materials in organic optoelectronics.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000499
Solid-State Dye-Sensitized Solar Cells with Conjugated Polymers as Hole-Transporting MaterialsW. Zhang, Y. Cheng, X. Yin, B. Liu*
In this Review the recent research on solid-state dye-sensitized TiO2 solar cells with conjugated polymers as hole-transporting materials is presented. These photovoltaic devices combine the distinctive features of the inorganic semiconductor, i.e. chemical and mechanical stability, with polymer specific properties like easy processability and adjustable functionality. The authors especially focus on the impact of the molecular polymer structure and the deposition on the device performance. The factors limiting energy conversation efficiency are discussed and strategies for improving the device performance are proposed.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000489
Liquid crystalline additives improve the energy conversion efficiency of polymer solar cellsS. Jeong, Y. Kwon, B.-D. Choi, G. Kwak*, Y. S. Han*
One of the most important obstacles in the commercial use of polymer solar cells is their low energy conversion efficiency. In [poly(3-hexylthiophene)]:[[6,6]-phenyl C61-butyric acid methyl ester] blend films nano-sized phase separation between the two materials proved to be the crucial feature to increase this value. Several attempts have been tried to realize this morphology. Among them, the additive technique is of high importance due to the simplicity of the phase separation on the nanoscale and the molecular structural ordering within these domains. The nematic liquid crystals 5CB and 8CB were incorporated as additives in the above mentioned polymer blend films and investigated in their application in polymer solar cells. The addition of the LC leads to an improved energy conversion efficiency of 3.72% (vs. 2.14% in the reference blend film without LC), which can be attributed to the increased absorbance, higher crystallinity of P3HT, larger domain size of PC61BM and enhanced electron/hole mobility. These results indicate that nematic liquid crystals can serve as processing additives to enhance the energy conversion efficiency of polymer solar cells without the need for post-thermal annealing of the polymer blend films.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000379
Side-chain liquid-crystalline polymers for dye-sensitized solar-cells applicationJ. S. Park, Y. H. Kim, M. Song, C.-H. Kim, M. A. Karim, J. W. Lee, Y.-S. Gal, P. Kumar, S.-W. Kang,* S.-H. Jin*
Dye-sensitized solar cells (DSSCs) have arisen tremendous interest as these devices can be produced in a facile and low-cost way for applications generating energy. However, the commonly incorporated liquid electrolytes cause potential problems i.e. leakage and volatilization of the organic solvents, which currently limits the long term stability of DSSCs. Solid and semi-solid substances are considered as an interesting alternative. For this purpose two side-chain liquid crystalline polymers were synthesized attaching the side-chains in a very controlled matter to the polymer backbone via click-chemistry. The new substances are incorporated as matrices for electrolytes in DSSCs. Eventhough the power conversion efficiency (4%) does not reach the performance of the liquid counterparts, a comparison with the non-liquid crystalline polymer polyacrylonitrile showed their improved photovoltaic performance. The authors attribute these observations to the liquid crystalline behavior, i.e. ion mobility and miscibility of the polymer-electrolyte components. These results are promising approaches for the development of new materials for enhanced DSSCs’ performance.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000264
Polymers for Organic Electronics - third part of the series on functional polymersWai-Yeung Wong,* Ben Zhong Tang*
"Beyond doubt Polymers for Organic Electronics is one of the hottest topics in the research area on advanced functional polymers" the guest-editors B. Z. Tang and W.-Y. Wong state in their essay introducing the third part of the series on functional polymers dedicated to polymers in organic electronics. Due to increasing energy prices there is an immense need for improved energy conversion technologies. Great effort is therefore spent into new materials for polymer solar cells, polymer light-emitting diodes, and polymer field-effect transistors. The guest-editors hope that this series will provide a forum to highlight recent developments as well as a strong motivation for further research on this fascinating topic.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000549
Liquid crystalline polymers with tunable photoluminescence color and polarized light emissionNobuhiro Kawatsuki,* Ryoichi Ando, Ryosuke Ishida, Mizuho Kondo, and Yuta Minami
N. Kawatsuki et al. present their results on tunable photoluminescent color and polarized light emission of fluorene derivatives reversibly embedded into a liquid crystalline polymer. The fluorene derivatives possess terminal pyridine rings and are able to form H-bonds to the side-on attached cinnamic acid moieties of the polymer thus varying the photoluminescence properties. Additionally, cinnamic acid changes its acidity when undergoing a [2 + 2] photo crosslinking reaction; hence the acidity of the material can be controlled via the degree of photoreaction. As the λmax of the photoluminescence depends on the extent of formed H-bonds correlating to the acidity of the material it can be tuned by the position of the N-atom in the pyridine as well as the degree of photoreaction of the cinnamic acid. The polymer bearing cinnamic acid side-groups can be employed as a photoalignment layer to obtain oriented materials possessing anisotropic photoluminescence. This behavior paves the way for applications in backlighting LC displays or polarized luminescent devices.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000183
New Thermoresponsive Luminescent Electrospun Nanofibers Prepared from Poly[2,7-(9,9-dihexylfluorene)]-block-poly(N-isopropylacrylamide)/PMMA BlendsPing Tzeng, Chi-Ching Kuo, Sung-Tso Lin, Yu-Chen Chiu, Wen-Chang Chen*
Novel luminescent electrospun polymer nanofibers are successfully prepared via a two-fluid spinneret for thermo-tunable colorimetric sensor applications. PF-b-PNIPAAm/PMMA electrospun fibers exhibit both reversible temperature-responsive wettability and PF aggregate size changes as the temperature is cycled between 20 and 40 °C.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000088
Synthesis and Characterization of Highly Luminescent Copolymers of Methyl Methacrylate and Eu-Complexed 5-Acryloxyethoxymethyl-8-hydroxyquinolineCun-Jin Xu, Bo-Geng Li*
A highly luminescent Eu-complex monomer featuring thenoyltrifluoroacetone and 5-acryloxyethoxymethyl-8-hydroxyquinoline was first designed and synthesized, which was then further copolymerized with methyl methacrylate to prepare Eu-containing copolymers. The copolymers exhibit typical intense luminescence of the Eu(III) ions even at low Eu content. Furthermore, these polymer luminophors can be cast into clear thin films with good thermal and moisture stable properties.
Macromol. Chem. Phys., DOI: 10.1002/macp.201000026
With Electron Beam Lithography to Sub-Micrometer-Patterning of Conjugated PolymersE. Fisslthaler, M. Sezen, H. Plank, A. Blümel, S. Sax, W. Grogger, and E. J. W. List*
Spin coating, the most common deposition method for polymers, is not suitable for the production of patterned devices. However, the fabrication of devices with sub-micrometer active device dimensions will, open new possibilities for fundamental studies and enable improvements in device performance. List and co-workers have therefore added an electron beam lithography step to the device fabrication process and by this could fabricate patterned light emitting polymer layers with features as small as 2 μm. The patterning technique can be applied for all types of conjugated materials and it could even be combined with a fast 'large scale' structuring methods like inkjet printing, to allow for refinement of these patterns on a micrometer scale.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900665
Luminescent Mechanochromic SensorsFunctional Polymers: Luminescent Mechanochromic Sensors
Joseph Lott and Christoph Weder*
Luminogenic polymers with stimuli-responsive properties can be prepared by incorporating small amounts of excimer forming sensor dyes into various host polymers. C. Weder and J. Lott produce luminogenic mechanochromic thin films by blending cyano-substituted excimer-forming oligo(phenylene vinylene) dyes with two fluorinated host polymers of similar chemical composition but different crystallinity. In agreement with previous findings, aggregate size and matrix crystallinity were shown to be important factors determining sensor performance. The underlying mechanism - dispersion of small aggregates of the excimer forming sensor molecules upon plastic deformation of polymer crystallites - can be exploited in a range of semicrystalline polymer hosts.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900476
Copolymer of Fluorene and Triphenylamine Moieties as ChemosensorRong Yang, Weibing Wu, Wenyu Wang, Zhen Li,* and Jingui Qin
Conjugated polymer-based fluorescent (CPF) sensors, which generally contain binding positions such as nitrogen, oxygen, and sulfur atoms to interact with different analytes to give detectable optical signals, have attracted much attention in recent years. Zhen Li and co-workers have successfully prepared a new imidazole-functionalized copolymer of fluorene and triphenylamine bearing imidazole groups in the side chain comparing the direct and postfunctional synthetic route, where the direct copolymeriztion strategy proved to be more successful. The chemosensing behavior of the obtained copolymer was carefully studied. The utilization of the metal ion chemosensors to probe anions by an indirect strategy presents a novel way of developing new chemosensors with a detection limit of cyanide down to 1.8 × 10-5 mol⋅L-1 (0.47 ppm).
Macromol. Chem. Phys., DOI: 10.1002/macp.200900370
A New Class of Heat-Resistant and Fluorescent PolymersShotaro Yukawa, Akitoshi Omayu, and Akikazu Matsumoto*
Vinyl polymers with fluorescent chromophores in their side chain can be conveniently prepared by chain polymerizations, but they lack thermal stability as compared with heat-resistant condensation polymers. In analogy to the alternating copolymerization of N-alkylmaleimides (RMI) with isobutene (IB), which yields high-molecular-weight copolymers [poly(RMI-alt-IB)s] with excellent thermal stabilities, Akikazu Matsumoto and co-workers designed poly(RMI-alt-IB)s containing pyrenyl and alkynylpyrenyl moieties in the side chain. Due to their superior transparency and mechanical properties along with the excellent thermal stability these RMI-IB copolymers modified by a fluorophore in the side chain can be considered as the new type of heat-resistant and fluorescent polymers.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900326
Safe and Efficient Metallo-Polymers for PLEDsCheuk-Lam Ho, Chung-Hin Chui,* Wai-Yeung Wong,* Shawkat M. Aly, Daniel Fortin, Pierre D. Harvey,* Bing Yao, Zhiyuan Xie, and Lixiang Wang
Although most of the work in this field of polymer light-emitting diodes (PLEDs) is focused on conjugated polymers that are comprised of organic building blocks, the interest in the properties of organometallic conjugated materials is also growing. Wai-Yeung Wong and co-workers from the Hong Kong Baptist University present the molecular design and optoelectronic properties of a novel platinum(II)-acetylide polymer containing 2,7-carbazole units. The polymer has been used to fabricate efficient PLEDs which exhibit a strong green-yellow electrophosphorescence and displayed the best efficiency of 4.7cd⋅A-1.This study represents the first example of efficient PLEDs exhibiting neat triplet emission under electrical excitation for metallopolyynes. On top of this, biological studies show that the metallo-polymer is non-cytotoxic in vitro on liver and breast derived human cells at reasonable doses rendering it a safe and promising materials for practical devices.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900351
Polyfluorenes with Pure Blue EmissionQiang Zhao, Shu-Juan Liu, and Wei Huang*
Due to their high photoluminescence quantum yields, charge-carrier mobility, and a good processibility polyfluorenes (PF) represent a class of promising polymers for the application in blue polymer light-emitting diodes (PLEDs). However, the appearance of long-wavelength green emission is a significant problem for this purpose. As a result, techniques for improving the color purity and stability of polyfluorenes are very important. In their Feature Article W. Huang and co-workers discuss the different routes they have gone to address this problem. Through various chemical approaches, including the incorporation of spirobifluorene units, heterofluorene units, hyperbranched, and starshaped structures into PF backbones, pure blue-emitting PFs with excellent color purity, and stability were obtained.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900263
Poly(carbazole)-Based Copolymers for PLED ApplicationsJin Su Park, Myungkwan Song, Sung-Ho Jin,* Jae Wook Lee,* Chan Woo Lee, and Yeong-Soon Gal
Polymer light-emitting diodes (PLEDs) exhibit many attractive properties, such as low driving voltage, a wide color range, low costs, flexibility and easy processing conditions. Among the π-conjugated polymers used for the production of PLEDs polymers containing carbazole or carbazole derivatives have attracted much attention due to their unique optical, electrical and chemical properties. J.-H. Jin, J. W. Lee and coworkers have synthesized a series of new carbazole-based π-conjugated copolymers incorporating a deep blue chromophore pendant group using the Suzuki coupling polymerization method. The resulting copolymers were found to be stable in air, and showed good solubility and high glass transition temperatures. This indicates that these copolymers are promising light-emitting materials. The maximum brightness and luminescence efficiency of the copolymer device were found to be 230 cd⋅m–2 and 0.28 cd⋅A–1 at 11V, respectively.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900207
Selective Chemosensor for Group 8 Metal IonsKyu-Nam Kim, Young-Wan Kwon, Dong Hoon Choi, and Jung-Il Jin*
Many conjugated polymers can be used as sensory materials due to their strong fluorescence in the visible wavelength region. Jung-Il Jin and co-workers designed a new fluorescing poly(p-phenylene vinylene) (PPV) derivative containing two oligo(oxyethylene) (OE) pendants per repeating unit. These groups lead to a good water solubility and are able to form complexes with a wide variety of metal ions. Among the 25 different metal ions studied Fe(III), Os(III) and Ru(III) are found to effectively quench the fluorescence of the synthesized polymer rendering it a sensitive and selective chemosensor for these ions.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900088
Dithienosilole in Conjugated Oligomers and PolymersJoji Ohshita*
Oligothiophenes and polythiophenes have been extensively studied as an important class of π-conjugated systems. This Feature Article describes the synthesis and properties of conjugated oligomers and polymers containing dithienosilole (DTS) units in their backbones, where the incorporation of DTS units enhances the electron affinity. The applications of DTS-containing oligomers and polymers to organic light-emitting diodes, organic photovoltaic cells, and organic thin-film transistors are also introduced.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900180
Heparin QuantificationJianbing Shi, Kan-Yi Pu, Ruoyu Zhan, Bin Liu*
Heparin is a biological molecule, which plays an important role in a number of physiological processes, such as cell growth and differentiation, and is widely used as an injectable anticoagulant to prevent thrombosis. However, a heparin overdose can induce thrombocytopenia, which is recognized as one of the most catastrophic complications of heparin treatment, hence making exact heparin sensing a highly critical issue. Bin Liu and co-workers present the synthesis of a cationic conjugated polymer containing 20 mol-% 2,1,3-benzothiadiazole (BT) which exhibits a good water solubility. The formation of interpolyelectrolyte complexes between the oppositely charged polymer and heparin facilitates energy transfer from the fluorene segments to the BT units within the polymer, leading to an intensity increase for the orange emission (585 nm) at the expense of the blue emission intensity at 412 nm. A practical calibration curve covering the whole range of the therapeutic dosing level of heparin (0.2 to 76 x 10-6 M) is thus obtained by correlating the changes in BT emission with the heparin concentration in buffer.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900080
Fluorescent Enzyme-Coupled Approach for Enzyme Detection Using Conjugated PolymersFude Feng, Libing Liu,* and Shu Wang*
Sensitive enzyme detections based on conjugated polymers (CPs) is of great interest due to its importance in clinical diagnosis, drug discovery and enzyme engineering. Shu Wang and co-workers present a simple, rapid, continuous and homogeneous fluorescent assay for β-galactosidase which combines an enzyme-coupled reaction and the signal amplification property of CPs. The procedure is based on a sequence of two coupled biocatalytic steps in which the β-galactosidase hydrolyzes its substrate to a phenol derivative followed by the conversion to quinone (secondary product) with fluorescence quenching ability by the tyrosinase. The fluorescence of PFP-SO3- is efficiently quenched by the quinone via an electron transfer process. The detection limit of this assay is less than 0.0005U x mL-1, which is better than that of the electrochemical method and comparable to that of the most sensitive chemiluminescent techniques. In principle, this sensor mechanism will extend the application window of CPs for wide-spectrum enzyme detections and could be expanded to a high-throughput manner.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900264
Luminescent Electrospun FibersHsieh-Chih Chen, Cheng-Liang Liu, Chi-Chung Bai, Nian-Hau Wang, Chih-Shan Tuan, Wen-Chang Chen*
Wen-Chang Chen and co-workers from the National Taiwan University successfully prepared luminescent electrospun fibers from 2,3-dibutoxy-1,4-poly(phenylene vinylene)/PMMA blends. The morphology of these fibers from core-shell to wire-like structure as well as the photophysical properties could be tuned by varying the solvent polarity and the conjugated moiety content. Moreover, highly-aligned DB-PPV/PMMA blend electrospun fibers with polarized emission were successfully prepared using a modified collector design. The prepared luminescence fibers could have potential applications as new light sources, smart textiles, and optoelectronic devices.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900097
Aligned Packing StructuresHiroshi Yamada, Caihong Xu, Aiko Fukazawa, Atsushi Wakamiya, and Shigehiro Yamaguchi*
Progress in the field of organic electronics highly depends on the development of new π-conjugated molecules with improved electronic and photophysical properties. One promising class of π-systems is the ladder-type π-conjugated compounds that consist of fully fused polycyclic skeletons. Yamaguchi and co-workers investigate a possible crystal engineering of ladder bridged oligo(π-phenylenevinylene) analogs by introducing alkyl chains on the bridging moieties. Their careful investigation regarding the photophysical properties in the crystalline state revealed that the all-parallel-aligned packing structure tends to cause a high fluorescence quantum yield.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900037
Luminogenic Polymers – The Series on Functional Polymers ContinuesBen Zhong Tang
Luminogenic polymers is one of the hot topics in polymer research. A large number of luminogenic polymers has been synthesized by incorporating π-conjugated units, such as double or triple bonds, or aromatic rings and their substituted derivatives. In his Essay, guest-editor Ben Zhong Tang emphasizes the importance of this class of polymers as sensory materials or polymer light-emitting diodes, and the problems and developments associated with these applications.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900173
Molecular Shapes of Polyacetylenes in their Liquid Crystalline PhasesKai-Peng Liu, Zhen-Qiang Yu, Jia-Hao Liu, and Er-Qiang Chen*
Derivatization of polyacetylene is a suitable way to overcome obstacles associated with PA processing, such as the low solubility and the tendency to oxidize. Beyond that, incorporation of functional pendants into the PA backbone may enhance the already existing electronic properties and even create novel functionalities. Er-Qiang Chen and coworkers summarize in their Feature Article in the Special Article Series in Macromolecular Chemistry and Physics the most important aspects of the molecular shapes of the monosubstituted polyacetylenes (MSPAs) in their liquid crystalline (LC) phases. Rod-like MSPAs and their columnar LC phases, as well as sheet-like MSPAs and their smectic LC phases are discussed in detail. Further research on the molecular engineering of MSPA may lead to new technological implications.
Macromol. Chem. Phys., DOI: 10.1002/macp.200900011
Helix-Sense-Selective PolymerizationShingo Hadano, Takuya Kishimoto, Tomonori Hattori, Daisuke Tanioka, Masahiro Teraguchi, Toshiki Aoki,* Takashi Kaneko, Takeshi Namikoshi, and Edy Marwanta
Looking at biopolymers like nucleic acids having various vital functions such as molecular recognition and catalytic ability associated with their well defined helical structure, it is obvious that the synthesis of well-organized one-handed helical polymers is an attractive and important area of research. Toshiki Aoki and co-workers have synthesized a series of substituted phenylacetylenes having various linear or branched alkyl groups with a chiral catalytic system. The influence of these alkyl groups on solubility, molecular weight, chiroptical properties, and crystallinity of the resulting polymers are discussed. A membrane fabricated form one of these polymers exhibits enantioselective permeability which is the first example to confirm directly the effect of a one-handed helical main chain on the chiral recognition ability.
Macromol. Chem. Phys., DOI: 10.1002/macp.200800594
PolymacrocyclesTakashi Kaneko,* Takahiro Horie, Shinji Matsumoto, Masahiro Teraguchi, and Toshiki Aoki
T. Kaneko and coworkers synthesized a series of novel phenylacetylene monomers with a built-in macrocycle consisting of phenyleneethynylene repeating units. They successfully polymerized these monomers with a rhodium catalyst, [Rh(nbd)Cl]2, to give the corresponding polymacrocycles as yellow-red powders, which were soluble in common organic solvents, such as toluene, chloroform and tetrahydrofuran. In spite of their steric bulkiness a high degree of polymerization of about 500 could be reached. The polymacrocycles are expected to be suitable for providing materials with unique functions, such as tubular channels, guest-host complexes and porous organic solids.
Macromol. Chem. Phys., DOI: 10.1002/macp.200800429
Disubstituted Polyacetylene Derivatives: Synthesis and Electroluminescent PropertiesS.-H. Yang, C.-H. Huang, C.-H. Chen, and C.-S. Hsu*
C.-S. Hsu and coworkers present the synthesis of a series of disubstituted polyacetylenes containing multi-fluorophenyl and cyclohexylphenyl side groups. The effect of the number and substitution position of these fluorine atoms on energy levels and luminescent efficiency are examined. The device performance can be promoted by blending a hole transporting material into the disubstituted polyacetylene (with the difluorophenyl group (PDPA-2F)) as the active layer or by using a light-emitting copolymer in which the PDPA-2F is copolymerized with a carbazole group (PDPA-2Fcab). The synthesized PDPA-2Fcab demonstrates the best performance of polyacetylene derivatives used as light emitting materials so far.
Macromol. Chem. Phys., DOI: 10.1002/macp.200800467
Induced Circular Dichromism of PolydiacetylenesS. Dei and A. Matsumoto*
A. Matsumoto and S. Dei present a detailed study on the synthesis of polydiacetylenes with phenylene substituents directly connected to the conjugating main chain in order to investigate the effects of the side chain structure on the chromatic properties of the polymers. They also report on the first example of an induced circular dichromism of a poyldiacetylene in combination with a chiral (1-cyclohexyl)ethylamine in the dispersion and in the solid state by an acid/base interaction, indicating a regularly twisted or helical layered structure.
Macromol. Chem. Phys., DOI: 10.1002/macp.200800488
Polydiacetylenes Supramolecules in Electrospun FibersJaewon Yoon and Jong-Man Kim*
Conjugated polymers have been studied extensively as a novel class of functional materials, with a special interest devoted towards the stimulus induced changes that take place in the electronic absorption and emission properties of these polymers. Jong-Man Kim and Jaewon Yoon discuss in a comprehensive study the fabrication of polydiacetylenes (PDAs) supramolecules in electrospun fibers. Various electrospinning conditions like molecular weight, the matrix polymer, and solvent concentration, on the efficiency of the formation of PDA-embedded micro/nanofibers are investigated. Besides that, UV-induced in situ polymerization during electrospinning allows for the fabrication of PDA-embedded fibers in one step. Since diverse DA monomers can be utilized, these PDA-embedded fibers should find great utility in the field of PDA-based chemosensor systems.
Macromol. Chem. Phys. DOI: 10.1002/macp.200800297
Functionality in ATRP: Functionalized Polymers and NanogelsD. J. Siegwart, J. K. Oh, H. Gao, S. A. Bencherif, F. Perineau, A. K. Bohaty, J. O. Hollinger, and K. Matyjaszewski*
Functionality is one of the key attributes of atom transfer radical polymerization (ATRP). This feature can be exploited to prepare functional materials for a variety of different applications. Matyjaszewski and co-workers discuss in their latest publication in Macromolecular Chemistry and Physics how they utilized ATRP for the synthesis of well-controlled polymers functionalized with biotin, pyrene, and peptides via reaction at terminal hydroxyl groups. In addition, they found that ATRP and click chemistry offered an efficient route for the synthesis of telechelic di-biotin polymers. These general methods can be applied to the formation of different functional materials conjugated with proteins, dyes, nucleic acids, and drugs.
Macromol. Chem. Phys. DOI: 10.1002/macp.200800337
Fluorene-Based Polymers by Different Click ReactionsMd. A. Karim, Y.-R. Cho, J. S. Park, T. I. Ryu, M. J. Lee, M. Song, S.-H. Jin,* J. W. Lee, and Y.-S. Gal
The 1,3-dipolar cycloaddition of an azide moiety and a triple bond has rapidly become the most popular click reaction to date. Sung-Ho Jin and coworkers present a systematic study on three different methods of click reactions, i.e. CuI-catalyzed, non-catalyzed, and CuI-catalyzed with end-capping, to synthesize fluorene-based polymers for dye-sensitized solar cells applications. The electro-optical properties, as well as the photovoltaic performance of these polymers are compared. The catalyzed click reaction leads to polymers with the highest power conversion efficiency, rendering this the most efficient synthetic route for the fabrication of promising materials for device applications.
Macromol. Chem. Phys. DOI: 10.1002/macp.200800329
Increased PEDOT Conductivity upon Cross-LinkingJames D. Mendez and Christoph Weder*
The wide application range of conducting materials has inspired the creation of electrical conducting polymers with unique properties. One key problem for polymer (semi)conductors is that the charge transport is usually limited by disorder effects, which prevent efficient interchain coupling and lead to materials with one-dimensional electronic properties. Mendez and Weder address this problem by introducing π-conjugated cross-links between the linear poly(3,4-ethylenedioxythiophene) (PEDOT) chains. These conjugated polymer networks indeed exhibit a conductivity increase of 36% as compared to their linear counterparts, while hardly changing the optical properties. Further optimization of these macromolecular systems will be a fruitful endeavor and result in materials with even better electrical conductivity.
Macromol. Chem. Phys. DOI: 10.1002/macp.200800317
Nanomechanical Actuators from Self-Organizable Dendronized cis-PPAsJonathan G. Rudick and Virgil Percec*
Polyarylacetylenes have attracted significant interest recently due to their helical conformation and potential optoelectronic properties. Among the challenges faced when developing functional polymers based on polyarylacetylenes is the inherent structural instability of the polyene backbone. Self-assembling dendrons sterically disfavor the cisoid conformation through which 6-electrocyclization proceeds in cis-polyarylacetylenes. V. Percec and J. G. Rudick discuss in their Feature Article how dendronized helical cis-polyphenylacetylenes (cis-PPAs) self-organized in oriented fibers are capable of displacing macroscopic objects 250 times their weight due to an unprecedented cisoid-to-transoid conformational isomerism of the polyene backbone. Generalizing this approach to other self-organizable dendronized polymers will provide a collection of nanomechanical actuators.
Macromol. Chem. Phys. DOI:10.1002/macp.200800271
Ionic Polyacetylene with Aromatic Functional GroupsGiseop Kwak,* Sung-Ho Jin, Jong-Wook Park, and Yeong-Soon Gal*
Within the last years, considerable progress has been made in areas like synthesis, characterization, and processing of conjugated polymers. Unfortunately, applications of these promising materials have remained limited because of solubility and thermal instability problems. G. Kwak and coworkers successfully synthesized an ionic conjugated polymer with two aromatic functional groups (pyridyl and phenylene) which proceeded well in polar organic solvents without any additional catalyst or initiator. A conjugated polyacetylene with designed aromatic substituents was achieved; the electrical conductivity of the iodine-doped polymer was 1.20 × 10–3 S cm–1. This polymer showed a photoluminescence maximum peak at 508 nm, and exhibited electrochemical stablility in the rage of –1.32 to +1.92 V.
Macromol. Chem. Phys. DOI:10.1002/macp.200800284
With Hydrosilylation to Functional PolymersJ. C. Sanchez and W. C. Trogler*
Polycarbosilanes comprise a whole range of desirable properties. High thermal stability, elastomeric behavior, diverse functional group tolerance, and electronic delocalization render them suitable candidates for the production of new ceramic precursors, fire-retardant materials, and flexible conducting polymers. This review focuses on the use of catalytic hydrosilylation of diynes for the synthesis of these new functional materials. With its tolerance of many functional groups, catalytic hydrosilylation offers one-step syntheses of both aliphatic and olefinic polymers and dendrimers whose electronic properties can be tuned selectively.
Macromol. Chem. Phys. DOI:10.1002/macp.200800235
Design and Properties of Functional Conjugated Organic PolymersC. Li and Y. Li*
In their Feature Article, C. Li and Y. Li summarize recent studies on the design and properties of conjugated polymers (polyacetylenes, poly(p-phenyleneethynylenes), and polydiacetylenes) derived from triple-bond containing building blocks and explore the potential applications of these materials. With an emphasis on the developments in their own group in recent years their intense attention is focused on constructing different molecular systems with enhanced light-harvesting efficiency, and determining the functional properties of conjugated organic polymers, which might be useful candidates for various potential applications.
Macromol. Chem. Phys. DOI:10.1002/macp.200800049
Promising Candidates for Polymer Light-Emitting DiodesW.-Y. Wong,* G.-J. Zhou, Z. He, K.-Y. Cheung, A. M.-C. Ng, A. B. Djurisic,* W.-K. Chan
W.-Y. Wong, A. B. Djurisic and coworkers report on the synthesis and characterization of two soluble, luminescent bithiazole-linked platinum(II) polyyne polymers that are suitable candidates for the construction of polymer light-emitting devices (PLEDs). Both polymers were found to be thermally stable over 340 °C. Furthermore, their good solubility in common organic solvents makes them suitable for solution processing, which is essential for a wide range of device applications.
Macromol. Chem. Phys. DOI:10.1002/macp.200800180
Poly(phenylacetylene)s Carrying Siloxy, Carbonate and Hydroxy Groups: Synthesis and PropertiesI. Saeed, Y. Shida, F. Z. Khan, M. Shiotsuki, T. Masuda*
In this work done by the Masuda’s group, a series of substituted poly(phenylacetylene)s carrying functional pendants with molecular weights up to ca. 6 x 106 were synthesized in excellent yields. Attempts to accomplish free-standing membrane fabrication by solution casting were successful for polymers with siloxy groups in the meta position and an augmentation in the gas permeability (especially CO2) was discerned in comparison with the unsubstituted poly(phenylacetylene) and poly(o-methylphenylacetylene).
Macromol. Chem. Phys. DOI:10.1002/macp.200800029
Construction of Functional Polymers from Acetylenic Triple-Bond Building BlocksB. Z. Tang
Many research groups have worked on the polymerizations of acetylenic monomers to explore their potential in the creation of functional polymers. A few examples of polymerization reactions for acetylenic monomers with one (monoyne), two (diyne) and three (triyne) triple bonds that furnish acetylenic polymers with novel structures and unique properties are discussed in this essay. Beyond that, Ben Zhong Tang as the guest editor of the Special Article Series called "New Frontiers in Functional Polymers" introduces the goal and the need for this series which will hopefully serve as a stimulus for new research efforts to realize the full potential of acetylenic monomers as a group of versatile building blocks for the construction of new functional polymers for high-technology innovations.
Macromol. Chem. Phys. DOI:10.1002/macp.200800228