Strategies for Tailoring LC-Functionalized Polymer: Probe Contribution of [Si-O-Si] versus [Si-C] Spacer to Thermal and Polarized Optical Performance 'Driven by' Well-Designed Grafting Density and Precision in Flexible/Rigid Matrix

摘要

A versatile strategy is highly desired to prepare well-designed side chain liquid crystal polymers (SCLCPs). Two rigid and topological SiH/Vinyl-functionalized polystyrenes (PSs), namely poly(4-vinylphenyldimethylsilane) (PVPDMS) and poly(4-vinylphenyl-1-butene) (PVSt), were synthesized via anionic polymerization (AP) and detailed; subsequently, Vinyl/SiH terminated LCs were treated with PVSt/PVPDMS via hydrosilylation to yield SCLCPs bearing [Si-O-Si]/[Si-C] spacers. Herein, well-designed grafting density, evaluated by H-1 NMR, was readily performed by the varying SiH to Vinyl feed mole ratio. The design systematically probes a cooperative effect of architectures on properties and allows for precision in flexible/rigid matrixes. Regardless, PB/PS systems with saturated addition displayed the best performances. Fundamentally, the study compared the dependence of polarized optical and thermal performances on [Si O Si] versus [Si C] spacer, which submitted to be driven by grafting density, providing the first access to tailoring polymer. SCLCPs exhibited essentially constant SmA, but inconsistent dynamic of spacer-induced contribution, in which AT was the same in complete addition as if nothing with spacer; surprisingly, followed by decreased grafting density, the decreasing trend in AT of [Si O Si] as spacer was fast, while that of [Si C] was slow. This phenomenon was further confirmed by POM. Furthermore, [Si O Si] was desired to obtain lower Tg and applicable to the advantageous "decoupling effect". Endeavor for tailoring SCLCPs and regulating devices, the appropriate spacer and grafting density advanced to an effective role.