Fully conjugated donor–acceptor block copolymers composed of poly(3-hexylthiophene) and poly(naphthalene bisimide) segments, P3HT-PNBI-P3HTs, were synthesized using quasi-living Grignard metathesis polymerization and the Yamamoto coupling reaction. Broad absorption in a range of 350–850 nm, which corresponded to the optical band gap of 1.46 eV, was observed for the P3HT-PNBI-P3HT thin films. In addition, the optical band gap decreased to 1.38 eV (the light absorption band extended to 893 nm) by thermal annealing, which was much smaller than those of previously reported donor–acceptor block copolymers (1.6–1.8 eV). The annealed P3HT:P3HT-PNBI-P3HT blend film (1:1 by weight) also exhibited broad absorption in the range of 350–950 nm. Cyclic voltammetry demonstrated that the P3HT-PNBI-P3HT thin films exhibited the oxidation and reduction properties derived from the P3HT and PNBI segments. The HOMO and LUMO levels were in the range of 5.57–5.60 and 4.22–4.27 eV, respectively. All-polymer solar cells using the P3HT:P3HT-PNBI-P3HT blend films achieved a power conversion efficiency of 1.28% with open-circuit voltage of 0.56 V, short-current of 4.57 mA/cm2, and fill factor of 0.50.

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Highly sulfonated multiblock copoly(ether sulfone)s applicable to proton electrolyte fuel cells (PEFCs) were synthesized by the coupling reaction of corresponding hydroxyl‐ terminated oligomers in the presence of highly reactive decafluorobiphenyl (DFB) as a chain extender, followed by postsulfonation with concentrated sulfuric acid. Their molecular weights were reasonably high as determined by viscosity measurement (ηinh = 0.72–1.58 dL/g). It was also confirmed that postsulfonation selectively took place in hydrophilic segments to yield highly sulfonated multiblock copolymers (IEC = 1.90–2.75 mequiv/g). The resulting polymers gave transparent, flexible, and tough membranes by solution casting. The 4b membrane, as a representative sample, demonstrated good mechanical strength in the dry state regardless of high IEC value (2.75 mequiv/g). The 4a–c membranes with higher IEC values (IEC = 2.75–2.79 mequiv/g) maintained high water uptake (13.7–17.7 wt %) at 50% RH and it was still high (7.4–8.5 wt %) at 30% RH. Proton conductivity of all membranes at 80 °C and 95% RH was higher than that of Nafion 117. Furthermore, the 4a membrane showed high proton conductivity, comparable with Nafion 117 in the range of 50–95% RH, and maintained high proton conductivity (2.3 × 10−3 S/cm) even at 30% RH. Finally, the surface morphology of the membrane was investigated by tapping mode atomic force microscopy, which showed well‐connected hydrophilic domains that could work as proton transportation channel. This phase separation and the high water uptake behavior probably contributed to high and effective proton conduction in a wide range of relative humidity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2757–2764, 2010

A new series of sulfonated multiblock copoly(ether sulfone)s applicable to proton exchange membrane fuel cells was synthesized. The multiblock copolymers were synthesized by the nucleophilic aromatic substitution of hydroxyl‐terminated oligomers in the presence of highly reactive decafluorobiphenyl (DFB) as a chain extender. Because of the high reactivity of DFB, the ether–ether interchange reaction, which could lead to a randomized polymer architecture, was prevented, and multiblock copolymers with high molecular weights were easily produced. The multiblock copolymers gave tough, flexible, and transparent membranes by solution casting. The ion exchange capacity values could be easily controlled by changing the sulfonated block ratios in the copolymers. The resulting membranes demonstrated good oxidative and dimensional stability and significantly higher proton conductivity than sulfonated random poly(ether sulfone) copolymers. The morphologies of the membranes were investigated by tapping mode atomic force microscopy, which showed that the multiblock membranes had a clear hydrophilic/hydrophobic separated structure. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3947–3957, 2008

Well-defined sulfur-containing polymers and block copolymers were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization of S-vinyl sulfide derivatives, in which the thioether moiety is directly connected to the vinyl group. We initially investigated RAFT polymerization of four different S-vinyl sulfide derivatives, phenyl vinyl sulfide (PVS), 4-chlorophenyl vinyl sulfide (CPVS), 2,4-dichlorophenyl vinyl sulfide (DCPVS), and 4-bromophenyl vinyl sulfide (BPVS). Three xanthate-type chain transfer agents (CTAs), a dithiocarbamate-type CTA, and a dithioester-type CTA were compared for these RAFT polymerizations. Reasonable control of the polymerization of PVS was confirmed by an observed linear increase in the molecular weight with the conversion, feasibility to control molecular weight based on the ratio of monomer consumed to the amount of CTA used, chain end structure determined by 1H NMR, and chain extension experiment. The RAFT polymerization of the bromo-substituted monomer (BPVS) also proceeded in the controlled fashion under the same conditions. Incorporation of optoelectronic groups, including anthracene, fluorene, diphenylamine, and phenothiazine on the bromophenyl pendant group of poly(BPVS) were accomplished by palladium-catalyzed postmodifications. We also investigated characteristic optoelectronic properties of modified polymers and block copolymers with two distinct electronic functionalities.