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

ABSTRACT 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 The diblock (P3HT‐b‐P3SiHT) and triblock (P3HT‐b‐P3SiHT‐b‐P3HT) copolymers can be synthesized based on Kumada catalyst‐transfer polycondensation. The block copolymer thin films formed a phase‐separated structure between P3HT and P3SiHT domains as observed by AFM and GIXS. In addition, block copolymers showed comparable or even higher hole mobility than P3HT homopolymers, probably due to enhanced phase‐separation and thereby charge transportation. Finally, the P3HT‐b‐P3SiHT‐b‐P3HT film showed lower tensile modulus and longer elongation at break than P3HT homopolymer and diblock copolymers.