Living Direct Arylation Polymerization via C–H Activation for the Precision Synthesis of Polythiophenes and Their Block Copolymers
Si-Lin Huang, Chen-Chen Ye, Y. Pan, Qiaoyun Liu, Chao Wang, Lei Xu
Abstract
P3HT, a typical conjugated polymer, is widely applied in field-effect transistors and photovoltaic devices owing to its excellent properties, relatively low cost, and synthetic versatility. However, existing P3HT synthesis methods suffer from poor atom economy, complicated procedures, and environmental pollution. Herein, we present a living direct arylation polymerization method via C–H bond activation, which eliminates the need for cumbersome Grignard, boron, and stannylated reagents. Polythiophene synthesis is achieved with 90% regioregularity, a narrow molecular weight distribution ( M w / M n ), and controlled molecular weight ( M n ) by using an air-stable palladium catalyst via catalyst-transfer polycondensation. The chemical structures of the resulting polythiophenes, which feature the Pd(II) complex at polymer chain ends, were confirmed by nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with end-group analysis, and chain-extension experiments. Furthermore, amphipathic polythiophene block copolymers and polythiophene- block -poly(phenyl isocyanide) were synthesized by using the isolated P3HT-Pd(II) as the macroinitiator, and their self-assembly was systematically investigated. The self-assembled amphipathic polythiophene block copolymers demonstrate intriguing fluorescence characteristics and emit white fluorescent light.