Synthesis of block copolymers comprised of poly(3‐hexylthiophene) segment with trisiloxane side chains and their application to organic thin film transistor

The demand of stretchability for a semiconducting polymer has increased to realize wearable devices and sensors. However, studies involving intrinsically stretchable π‐conjugated polymers are still limited. Here, we develop a soft‐polythiophene derivative, P3SiHT, with a trisiloxane unit in the side chains via a hexylene spacer unit. In addition, diblock (P3HT‐b‐P3SiHT) and triblock (P3HT‐b‐P3SiHT‐b‐P3HT) copolymers could be synthesized based on Kumada catalyst‐transfer polycondensation. The results of atomic force microscopy and grazing incidence small‐angle X‐ray scattering indicate that the block copolymer thin films form a phase‐separated structure between the P3HT and P3SiHT domains. The organic thin film transistor devices were prepared to assess the electrical properties of the block polymers. As a result, the block copolymers showed comparable or even higher hole mobility than that of P3HT homopolymer, thus due to the enhanced phase‐separation and thereby charge transportation. The mechanical test of the bulk films indicates that P3HT‐b‐P3SiHT‐b‐P3HT shows lower tensile modulus and longer elongation at break than P3HT homopolymer and other diblock copolymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1787–1794     

Synthesis,morphology, and field‐effect transistor characteristics of new crystalline–crystalline diblock copolymers of poly(3‐hexylthiophene‐block‐steryl acrylate)

We report the synthesis, morphology, and charge‐transporting characteristics of new crystalline–crystalline diblock copolymers, poly(3‐hexylthiophene‐block‐stearyl acrylate) (P3HT‐b‐PSA). Three different diblock copolymers, P1 , P2 , and P3 , with P3HT/PSA polymerization degree block ratios of 60/26, 60/50, and 60/360, respectively, were prepared for investigating the morphology‐property relationship and the dependence of optoelectronic properties on the block copolymer structure. Small‐ and wide‐angle X‐ray scattering indicated the presence of both P3HT and PSA crystalline domains and the presence of microphase separation among blocks. The transmission electron microscopy and atomic force microscopy results revealed that the diblock copolymers cast from chlorobenzene, tended to form needle‐like morphologies. The field‐effect mobilities of the diblock copolymers deposited on untreated SiO₂ substrates, decreased with increasing PSA block length. In a sharp contrast, the mobilities enhanced with increasing PSA content when the P3HT‐b‐PSA was deposited on phenyltrichlorosilane (PTS)‐treated substrates. The copolymers with a 60/360 P3HT/PSA ratio showed a good mobility of 4 × 10^?3 cm² V^?1 s^?1 and a high on/off ratio of 7 × 10⁶ on PTS‐treated substrates. This study highlighted the importance of the block ratio, the substrate and self‐assembly structures on the charge transport characteristics of the crystalline–crystalline conjugated diblock copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and self‐assembly of diblock copolymers composed of poly(3‐hexylthiophene) and poly(fluorooctyl methacrylate) segments

Regioregular poly(3‐hexylthiophene)‐b‐poly(1H,1H‐dihydro perfluorooctyl methacrylate) (P3HT‐b‐PFOMA) diblock copolymers were synthesized by atom transfer radical polymerization of fluorooctyl methacrylate using bromoester terminated poly(3‐hexylthiophene) macroinitiators in order to investigate their morphological properties. The P3HT macroinitiator was previously prepared by chemical modification of hydroxy terminated P3HT. The block copolymers were well characterized by ¹H NMR spectroscopy and gel permeation chromatography. Transmission electron microscopy was used to investigate the nanostructured morphology of the diblock copolymers. The block copolymers are able to undergo microphase separation and self‐assemble into well‐defined and organized nanofibrillar‐like micellar morphology. The development of the morphology of P3HT‐b‐PFOMA block copolymers was investigated after annealing in solvent vapor and also in supercritical CO₂. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of new low bandgap polyfluorene copolymers for bulk heterojunction solar cells

Two new low bandgap alternating polyfluorene copolymers based on dioctylfluorene and donor‐acceptor‐donor monomers have been synthesized via a Suzuki polymerization reaction. The resulting copolymers have low optical bandgaps at 1.99–1.98 eV. The bulk heterojunction polymer solar cells were fabricated with the conjugated polymers as the electron donor and 6.6‐phenyl C₆₁‐butyric acid methyl ester as the electron acceptor. The power conversion efficiencies of the solar cells based on copolymers 1 and 2 are 0.37 and 0.42%, respectively, under the illumination of AM 1.5, 100 mW/cm². The results indicate that the two copolymers are promising conjugated polymers for polymer solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5336–5343, 2009     

Synthesis,micellar structures,and multifunctional sensory properties of poly(3‐hexylthiophene)‐block‐poly(2‐(dimethylamino)ethyl methacrylate) rod‐coil diblock copolymers

We report the synthesis, micellar structures, and multifunctional sensory properties of new conjugated rod‐coil block copolymers, poly(3‐hexylthiophene)‐block‐poly(2‐(di methylamino)ethylmethacrylate)(P3HT‐b‐PDMAEMA). The new copolymers, synthesized by atom transfer radical polymerization of P3HT macroinitiator, consisted PDMAEMA coil lengths of 43, 65, and 124 repeating units. All the P3HT‐b‐PDMAEMA copolymers exhibit a similar low critical solution temperature in water around 33 °C. The micellar structures of the synthesized polymers were characterized by AFM, TEM, and dynamic light scattering, by varying temperature, pH, and water/THF composition. The micelles of P3HT₂₀‐b‐PDMAEMA₄₃ in water had a reversible size change from 75 ± 5 nm to 132 ± 5 nm on heating from 25 to 55 °C and reduced to the original size during cooling. In addition, the micellar size also showed a significant pH dependence, changing from 67 ± 8 nm (pH = 12) to 222 ± 6 nm (pH = 4), depending on the protonation of the PDMAEMA blocks and their electrostatic repulsion. The micellar structure of three P3HT‐b‐PDMAEMA copolymers changed from spheres, to vesicles, and finally to larger sphere micelles as the solvent composition varied from 0 to 100 wt % water in the mixed solvent. The different micellar structures of P3HT₂₀‐b‐PDMAEMA₄₃ solution led to a red‐shift on the absorption or photoluminescence spectra and exhibited the emission colors of yellow, orange, red, and dark red with increasing the water content. This study suggested that new copolymers had potential applications as multifunctional sensory materials toward temperature, pH, and solvent. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of pH sensitive poly(glycidol)‐b‐poly(4‐vinylpyridine) block copolymers

Block copolymers of poly(glycidol)‐b‐poly(4‐vinylpyridine) were obtained by ATRP of 4‐vinylpyridine initiated by ω‐(2‐chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pK_a value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782–1794, 2009     

Exploring the influence of acceptor content on semi‐random conjugated polymers

A family of diketopyrrolopyrrole (DPP)‐incorporated P3HT based semi‐random copolymers was synthesized and their optical, electronic and photovoltaic properties were investigated. For the first time, the influence of acceptor content on semi‐random copolymers was explored in the broad range of 10–40% acceptor. A mixture of DPP acceptor units with different side chains (ethylhexyl and decyltetradecyl) was incorporated into each copolymer to improve solubility and film quality. Increased DPP content in the polymer backbone resulted in broadened absorption between 350 and 900 nm, resulting in a monotonic decrease in optical band gap (E_g) of the polymers from 1.49 to 1.37 eV. Highest occupied molecular orbital (HOMO) energy levels showed an increase from 10% DPP to 20–30% DPP, while decreasing for 40% DPP. V_oc values followed a consistent trend with HOMO energy levels. Semi‐random copolymers showed significantly improved photovoltaic properties compared with P3HT. Bulk heterojunction solar cells fabricated from the semi‐random copolymers blended with PC₆₁BM exhibited high short‐circuit current densities (J_sc) up to 10.29 mA/cm² and efficiencies up to 4.43%. A new method of methanol treatment was developed and applied to the semi‐random copolymers resulting in high fill factors approaching 0.70 under ambient conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3884–3892     

Random poly(3‐hexylthiophene‐co‐3‐cyanothiophene‐co‐3‐(2‐ethylhexyl)thiophene) copolymers with high open‐circuit voltage in polymer solar cells

For the purpose of developing poly(3‐hexylthiophene) (P3HT) based copolymers with deep‐lying highest occupied molecular orbital (HOMO) levels for polymer solar cells with high open‐circuit voltage (V_oc), we report a combined approach of random incorporation of 3‐cyanothiophene (CNT) and 3‐(2‐ethylhexyl)thiophene (EHT) units into the P3HT backbone. This strategy is designed to overcome CNT content limitations in recently reported P3HT‐CNT copolymers, where incorporation of more than 15% of CNT into the polymer backbone leads to impaired polymer solubility and raises the HOMO level. This new approach allows incorporation of a larger CNT content, reaching even lower‐lying HOMO levels. Importantly, a very low HOMO level of ?5.78 eV was obtained, representing one of the lowest HOMO values for exclusively thiophene‐based polymers. Lower HOMO levels result in higher V_oc and higher power conversion efficiencies (PCE) compared to the previously reported P3HT‐CNT copolymers containing only 3‐hexylthiophene and CNT units. As a result, solar cells based on P3HT‐CNT‐EHT(15:15) , which contains 70% of P3HT, 15% of CNT and 15% of EHT, yield a V_oc of 0.83 V in blends with PC₆₁BM while preserving high fill factor (FF) and high short‐circuit current density (J_sc), resulting in 3.6% PCE. Additionally, we explored the effect of polymer number‐average molecular weight (M_n) on the optoelectronic properties and solar cell performance for the example of P3HT‐CNT‐EHT(15:15). The organic photovoltaic (OPV) performance improves with polymer M_n increasing from 3.4 to 6.7 to 9.6 kDa and then it declines as M_n further increases to 9.9 and to 16.2 kDa. The molecular weight study highlights the importance of not only the solar cell optimization, but also the significance of individual polymer properties optimization, in order to fully explore the potential of any given polymer in OPVs. The broader ramification of this study lies in potential application of these high band gap copolymers with low‐lying HOMO level in the development of ternary blend photovoltaics as well as tandem OPV. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1526–1536     

Synthesis and characterization of cyclic P3HT as a donor polymer for organic solar cells

In this study, cyclic poly(3‐hexylthiophene‐2,5‐diyl) (c‐P3HT) with a controlled M_n was synthesized by the intramolecular cyclization of α‐bromo‐ω‐ethynyl‐functionalized P3HT via the Sonogashira coupling reaction. The effect of the cyclic structure, which does not have terminal groups of polymers, on the photoelectric conversion characteristics was investigated in comparison to linear P3HT (l‐P3HT). c‐P3HT was successfully synthesized with M_n ≈ 17,000, dispersity ≈ 1.2, and regioregularity ≈ 99%. The hole mobility was determined to be 5.1 × 10^?4 cm² V^?1 s^?1 by time‐of‐flight (TOF) experiment. This was comparable to that of l‐P3HT of 5.6 × 10^?4 cm² V^?1 s^?1. Organic solar cell systems were fabricated with each polymer by blending them with [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM). The l‐P3HT:PC₇₁BM system showed a dispersive TOF photocurrent profile for electron transport, whereas a nondispersive profile was observed for c‐P3HT:PC₇₁BM. In addition, an amount of collected electrons in c‐P3HT:PC₇₁BM was greater than that in l‐P3HT:PC₇₁BM for TOF experiments. The photoelectric conversion characteristics were improved by using c‐P3HT rather than l‐P3HT (power conversion efficiency [PCE] = 4.05% vs 3.23%), reflecting the nondispersive transport and the improvement of electron collection. PCEs will be much improved by applying this cyclic concept to highly‐efficient OSC polymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 266–271     

Annealing effect on performance and morphology of photovoltaic devices based on poly(3‐hexylthiophene)‐b‐poly(ethylene oxide)

Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of all‐conjugated poly(3‐hexylthiophene)‐block‐ poly(3‐(4′‐(3″,7″‐dimethyloctyloxy)‐3′‐pyridinyl)thiophene) and its blend for photovoltaic applications

New all‐conjugated block copolythiophene, poly(3‐hexylthiophene)‐block‐poly(3‐(4′‐(3″,7″‐dimethyloctyloxy)‐3′‐pyridinyl)thiophene) (P3HT‐b‐P3PyT) was successfully prepared by Grignard metathesis polymerization. The supramolecular interaction between [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) and P3PyT was proposed to control the aggregated size of PCBM and long‐term thermal stability of the photovoltaic cell, as evidenced by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and optical microscopy. The effect of different solvents on the electronic and optoelectronic properties was studied, including chloroform (CL), dichlorobenzene (DCB), and mixed solvent of CL/DCB. The optimized bulk heterojunction solar cell devices using the P3HT‐b‐P3PyT/PCBM blend showed a power conversion efficiency of 2.12%, comparable to that of P3HT/PCBM device despite the fact that former had a lower crystallinity or absorption coefficient. Furthermore, P3HT‐b‐P3PyT could be also used as a surfactant to enhance the long‐term thermal stability of P3HT/PCBM‐based solar cells by limiting the aggregated size of PCBM. This study represents a new supramolecular approach to design all‐conjugated block copolymers for high‐performance photovoltaic devices. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

One‐pot synthesis of conjugated poly(3‐hexylthiophene)‐b‐poly(phenyl isocyanide) hybrid rod–rod block copolymers and its self‐assembling properties

In this article, the synthesis of a series of conjugated rod–rod block copolymers based on poly(3‐hexylthiophene) (P3HT) and poly(phenyl isocyanide) (PPI) building blocks in a single pot is presented. Ni‐catalyzed Grignard metathesis polymerization of 2,5‐dibromo‐3‐hexylthiophene and subsequent addition of 4‐isocyanobenzoyl‐2‐aminoisobutyric acid decyl ester in the presence of Ni(dppp)Cl₂ as a single catalyst afford P3HT‐b‐PPI with tunable molecular weights and compositions. In solid state, microphase separation occurred as differential scanning calorimetric analysis of P3HT‐b‐PPI revealed two glass transition temperatures. In solutions, the copolymers can self‐assemble into spherical aggregates with P3HT core and PPI shell in tetrahydrofuran and exhibit amorphous state in CHCl₃. However, atomic force microscopy revealed that the block copolymers self‐assemble into nanofibrils on the substrate. These unique features warrant the resultant conjugated rod–rod copolymers' potential study in organic photovoltaic and other electronic devices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2939–2947     

Synthesis of multiarmed poly(3‐hexyl thiophene) star polymer with microgel core by GRIM and ATRP methods

Regioregular poly(3‐hexyl thiophene) (rr‐P3HT)‐based star polymers were synthesized by a crosslinking reaction of the linear rr‐P3HT macroinitiator and ethylene glycol dimethacrylate (EGDMA) crosslinker through Ru‐based atom transfer radical polymerization (ATRP), where the rr‐P3HT macroinitiator was prepared by Grignard metathesis method (GRIM) followed by end functionalization of the ATRP initiator with chlorophenylacetate (CPA) to the rr‐P3HT. Relatively high molecular weight of the star polymers were obtained (M_p = 8,988,000 g/mol), which consisted of large numbers of the rr‐P3HT arm chains radiating from the EGDMA‐based microgel core. The yield of the star polymers were strongly affected by the added amount of the EGDMA crosslinker. The crystalline structure of the rr‐P3HT by intermolecular π‐π stacking interaction gradually decreased as the star polymer formed, which was confirmed by differential scanning calorimeter (DSC), atomic force microscopy (AFM), and electro‐optical analyses. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and morphology of all‐conjugated donor–acceptor block copolymers based on poly(3‐hexylthiophene) and poly(naphthalene diimide)

A series of all‐conjugated diblock and triblock copolymers comprised of poly(naphthalene diimide) (PNDI)‐based n‐type and the poly(3‐hexylthiophene) (P3HT) segments could be synthesized via the Kumada catalyst‐transfer polycondensation process. The crystalline structures and chain orientation of the block copolymer thin films were systematically studied by grazing incident wide‐angle X‐ray scattering (GIWAXS). The GIWAXS results indicated that both the P3HT and PNDI segments in the block copolymers form exclusive crystalline domains in which the P3HT domain aligns with an edge‐on rich orientation, and the PNDI domain aligns with a face‐on rich orientation. In contrast, the blend films of the P3HT and PNDI homopolymers also show two distinguished crystalline domains in which the P3HT domain aligns with an edge‐on rich orientation, and the PNDI domains align in different ways depending on the chemical structure of n‐type polymers, that is, PNDI1Th is isotropically dispersed, while PNDI2Th aligns with a face‐on rich orientation. In addition, the effect of thermal annealing on the crystalline behavior of the block copolymers is reported. The GIWAXS results indicated that thermal annealing increases the crystallinity of both segments without affecting their chain orientation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1139–1148     

Synthesis and stability of linear and star polymers containing [C60] fullerene

Linear and symmetric star block copolymers of styrene and isoprene containing [C₆₀] fullerene were synthesized by anionic polymerization and appropriate linking postpolymerization chemistry. In all block copolymers, the C₆₀ was connected to the terminal polyisoprene (PI) block. The composition of the copolymers was kept constant (～30% wt PI), whereas the molecular weight of the diblock chains was varied. The polymers were characterized with a number of techniques, including size exclusion chromatography, membrane osmometry, and ¹H NMR spectroscopy. The combined characterization results showed that the synthetic procedures followed led to well‐defined materials. However, degradation of the fractionated star‐shaped copolymers was observed after storage for 2 months at 4 °C, whereas the nonfractionated material was stable. To further elucidate the reasons for this degradation, we prepared and studied a four‐arm star copolymer with the polystyrene part connected to C₆₀ and a six‐arm star homopolymer of styrene. These polymers as well as linear copolymers end‐capped, through ? N<, with C₆₀ were stable. Possible reasons are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2494–2507, 2001     

Synthesis and properties of fluorene‐based polyheteroarylenes for photovoltaic devices

Novel copolymers consisting of the alternating push–pull comonomers fluorene and thieno[3,4‐b]pyrazine/quinoxaline were synthesized by a palladium‐catalyzed Suzuki cross‐coupling reaction in 60–80% yields. The structure of the deeply colored copolymers was confirmed with ¹H and ¹³C NMR. All the new materials were characterized with spectroscopic and electrochemical methods. Bulk heterojunction organic solar cells based on some of the novel polymers in combination with the well‐known fullerene acceptor [6,6]‐phenyl C₆₁–butyric acid methyl ester were fabricated, and their photovoltaic parameters were measured. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6952–6961, 2006     

Acceptor–acceptor conjugated copolymers based on perylenediimide and benzothiadiazole for all‐polymer solar cells

Donor–acceptor (D–A) conjugated copolymers are one of known classes of organic optoelectronic materials and have been well developed. However, less attention has been paid on acceptor–acceptor (A–A) conjugated analogs. In this work, two types of A–A conjugated copolymers, namely P1‐Cn and P2‐Cn (n is the carbon number of their alkyl side chains), were designed and synthesized based on perylenediimide ( PDI ) and 2,1,3‐benzothiadiazole ( BT ). Different from P1‐Cn , P2‐Cn polymers have additional acetylene π‐spacers between PDI and BT and thus hold a more planar backbone configuration. Property studies revealed that P2‐Cn polymers possess a much red‐extended UV–vis absorption spectrum, stronger π–π interchain interactions, and one‐order larger electron mobility in their neat film state than P1‐Cn . However, all‐polymer solar cells using P1‐Cn as acceptor component and poly(3‐hexyl thiophene) or poly(2,7‐(9,9‐didodecyl‐fluoene)‐alt?5,5′‐(4,7‐dithienyl‐2‐yl‐2,1,3‐benzothiadiazole) as donor component exhibited much better performance than those based on P2‐Cn . Apart from their backbone chemical structure, the side chains were found to have little influence on the photophysical, electrochemical, and photovoltaic properties for both P1‐Cn and P2‐Cn polymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1200–1215     

Synthesis and Photoconductivity Study of C60‐Containing Styrene/Acrylamide Copolymers

The C₆₀‐containing copolymers were prepared by reaction of styrene (St)/acrylamide (Am) copolymers with C₆₀ in toluene. By means of UV‐Vis spectroscopy, the C₆₀ content in the copolymers was determined to be up to 1.45 wt.‐%. The results show that with increasing the amide molar fraction in the copolymers, the C₆₀ content increases and the molar ratio C₆₀/amide group decreases. It was also revealed that the reactivity of the amide group with respect to C₆₀ could be enhanced by increasing the reaction temperature. C₆₀‐containing St/Am copolymers were characterized by DSC, GPC, XRD and UV‐Vis spectroscopy. Experimental results indicate that these C₆₀‐containing polymers reveal good photoconductivity, with the t_1/2 value of the better one (B8) being about 1.88 s, and photoconductivity could be enhanced on increasing the C₆₀ content in the copolymers.     

Poly(3‐hexyl thiophene)‐b‐poly(N‐isopropyl acrylamide): Synthesis and its composition dependent structural,solubility, thermoresponsive,electrochemical, and electronic properties

Conjugated block copolymers consisting of poly(3‐hexyl thiophene) (P3HT) and a thermoresponsive polymer poly(N‐isopropyl acrylamide) (PNIPAM) with varying composition have been synthesized by facile click reaction between alkyne terminated P3HT and azide terminated PNIPAM. The composition‐dependent solubility, thermoresponsive property in water, phase behavior, electrochemical, optical, and electronic properties of the block copolymers were systematically investigated. The block copolymers with higher volume fraction of PNIPAM form thermoresponsive spherical micelles with P3HT‐rich crystalline cores and PNIPAM coronas. Both X‐ray and atomic force microscopic studies indicated that the blocks copolymers showed well‐defined microphase separated nanostructures and the structure depended on the composition of the blocks. The electrochemical study of the block copolymers clearly demonstrated that the extent of charge transport through the block copolymer thin film was similar to P3HT homopolymer without any significant change in the band gap. The block copolymers showed improved or similar charge carrier mobility compared with the pure P3HT depending on the composition of the block copolymer. These P3HT‐b‐PNIPAM copolymers were interesting for fabrication of optoelectronic devices capable of thermal and moisture sensing as well as for studying the thermoresponsive colloidal structures of semiconductor amphiphilic systems. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1785–1794     

Toward low‐band gap dithienophosphole copolymers for an application in organic solar cells

Two functionalized dithieno[3,2‐b:2′,3′‐d]phospholes with solubilizing groups have been synthesized that allow for the generation of a series of π‐conjugated AB‐ and ABC‐copolymers. The polymers obtained show notable optoelectronic properties with red‐shifted absorption and emission in the orange to red section of the optical solar spectrum. Although combination of dithienophosphole units with fluorene building blocks gives access to processable polymers with band gaps between 2.2 and 2.3 eV in solution and 2.0 eV in the solid state, an ABC copolymer based on dithienophosphole, fluorene, and bis(thienyl)benzothiadiazole units was found to not only exhibit a suitable band gap for solar cell applications (solution: 2.0 eV; solid state: 1.7 eV) but also showed good solubility as well as good electron transfer properties in the presence of fullerene (C₆₀). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8179–8190, 2008