Living Polymerization Strategy for Conjugated Multiblock Copolymers: A Systematic Study of Structure–Property Relationships in Stretchability and Charge Transport

Achieving high mechanical stretchability while maintaining charge carrier mobility in semiconducting polymers remains a central challenge due to their intrinsic trade-off. Conjugated multiblock copolymers (CMPs) incorporating semiconducting and elastomeric segments represent a promising design strategy to overcome this limitation, yet a systematic understanding of how structural parameters influence material properties and device performances is still lacking. To address this issue, we chose a model polymer, poly(3-hexylthiophene) (P3HT), and systematically constructed its library precursors with independently varied molecular weight, dispersity, and end-group fidelity. Then, these precursors were incorporated into CMPs containing flexible polydimethylsiloxane (PDMS) over a broad composition range (0-75 mol%). As a result, this design enabled deconvolution of the individual effects of each structural parameter on CMP performance. Notably, CMPs incorporating well-defined P3HT blocks exhibited significantly enhanced stretchability (>300%) while retaining high hole mobility, in contrast to those prepared using P3HT from uncontrolled polymerization. These results underscore the advantage of living polymerization in precisely tailoring conjugated polymer architectures and optimizing the mechanical and electronic properties of stretchable semiconducting materials, while also offering a platform that may be extended to other conjugated polymers.