Thermo-crosslinking assisted preparation of thiol-acrylate main-chain liquid-crystalline elastomers

Thiol-acrylate main-chain liquid-crystalline elastomers (MC-LCEs) are currently widely used in LCE application research work. The current preparations of thiol-acrylate MC-LCE materials generally based on two-step thiol-acrylate Michael addition and photopolymerization (TAMAP). By this methodology, the permanently programmed monodomain of LCE matrices were achieved via a second-step photopolymerization reaction of the excess acrylate groups after the first step of "click" reaction of thiol-acrylate Michael-addition, in which the initial LCE networks were synthesized, and the stress-aligning process. In order to overcome the limitations of TAMAP in the preparations of LCE materials or LCE devices with special requirements of dimensions, components or structures, etc., for the first time we developed a way of two-step thiol-acrylate Michael addition and thermal polymerization (TAMAT). The second-step polymerization reaction of the excess acrylate groups was implemented by thermal initiation approach. Under the action of the selected thermal-initiator and appropriate temperature condition, the thiol-acrylate MC-LCEs could be prepared with well quality and reproducibility by TAMAT, and had consistent structure, properties and performances with those prepared by TAMAP, thus confirmed the high effectiveness and practicability of TAMAT methodology in the preparations of thiol-acrylate MC-LCE materials.