Synthesis of ABCBA-type miktoarm H-shaped copolymers with poly(3-hexylthiophene) segments and their application to intrinsically stretchable photonic transistor memory

Abstract

Recently, semiconducting polymers with intrinsic elasticity have garnered attention for their application in wearable devices. Herein, we synthesized a novel ABCBA-type miktoarm H-shaped copolymer (where A, B, and C represent polystyrene (PS), poly(3-hexylthiophene) (P3HT), and poly(n-butyl acrylate) (PⁿBA), respectively) via a Cu-catalyzed azide–alkyne cycloaddition reaction between in-chain-functionalized PS-b-P3HT with an alkynyl group and α,ω-chain-end-functionalized PⁿBA with azide groups. The thin films of the ABCBA-type miktoarm H-shaped copolymers exhibited high elasticity because of an inner PⁿBA segment with a low glass transition temperature and good photonic transistor memory properties because of outer PS-b-P3HT segments. They also exhibited good memory endurance along write–read–erase–read cycles, a wide memory window, a high ON/OFF ratio, and excellent retention properties. Upon stretching, the polymer films exhibited crack-free morphologies wherein large-ranged phase-separated domains were sacrificed to dissipate the applied stress while maintaining short-ranged lamellar crystal structures. Our results establish a pioneering strategy for creating intrinsically stretchable memory using ABCBA-type miktoarm H-shaped copolymers.