Segmented Thermoplastic Polymers Synthesized by Thiol–Ene Click Chemistry: Examples of Thiol–Norbornene and Thiol–Maleimide Click Reactions

Abstract

Thiol–ene click reactions are used to synthesize segmented thermoplastic materials for the first time via a soft segment + hard segment + chain extender approach that is commonly used to synthesize thermoplastic polyurethane elastomer (TPU). We employ a relatively long chain difunctional thiol (2500 g/mol) as soft segment, a small-molecule thiol as chain extender, and rigid cyclic-ene monomers, including norbornene (containing either urethane or urea linkages in the backbone) and maleimide, as hard segments to achieve thiol–norbornene and thiol–maleimide thermoplastics. The majority of the thiol–norbornene polymers synthesized with 45% or 55% urethane-based norbornene hard segments exhibit phase separation with broad interfaces as indicated by dynamic mechanical analysis (DMA) and hold promise as both thermoplastic elastomers competitive with TPUs and broad-temperature-range damping materials. Thiol–norbornene polymers synthesized with 50% urea-based norbornene hard segments are nanophase separated with s...