One-Pot Synthesis of Fully Conjugated Amphiphilic Block Copolymers Using Asymmetrically Functionalized Push–Pull Monomers

Developing a fully conjugated block copolymer with a specific molecular weight and block ratio is crucial forunderstanding the impact of the bulk heterojunction morphologyon device performance in organic photovoltaic devices. Herein, wehave revealed a strategy to synthesize fully conjugated amphiphilicdiblock copolymers in one pot by combining Suzuki and Stillepseudoliving polymerizations. Our strategy was to synthesizeasymmetrically functionalized push-pull monomers as precursorsfor the synthesis of the donor polymer poly[4,8-bis(5-(2-ethylhexyl)-4-hexylthiophene-2-yl)-benzo[1,2-b:4,5b ']-dithiophenebenzo [c][1,2,5]thiadiazole]p(BDT-BT)and theacceptor polymer poly[N,N '-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5 '-(2,2 '-bithiophene)p(NDI-TT). The acceptor monomer (M1) was synthesized withtributyltin and triflate functionalities, whereas the donor monomer (M2) was prepared with MIDA boronate and bromide groups.These heterobifunctional acceptor and donor monomers were suitable for Stille and Suzuki polymerizations, respectively. Initially,TfOPh-p(NDI-TT)was synthesized by pseudoliving Stille polymerization with a single triflate (OTf) end group and specificmolecular weight. Subsequently,TfOPh-p(NDI-TT)was used as a macroinitiator to grow an amphiphilic diblock copolymer(BCP1) via a grafting-into approach, where the donor polymer block was grown using pseudoliving Suzuki polymerization. Lastly,one-pot synthesis of the amphiphilic diblock copolymer (BCP2) was established using optimized conditions developed for stepwise block copolymer synthesis