Well-defined side-chain liquid-crystalline polysiloxanes

Abstract

A route to well-defined side-chain liquid-crystalline polysiloxanes (ratio of weight- to number-average molar masses M̄w/M̄n < 1.2 is reported. Anionic ring-opening polymerization of pentamethylvinylcyclotrisiloxane yielded a poly(dimethylsiloxane-co-methylvinylsiloxane) backbone. A flexible disiloxane spacer was used to connect 4-(ω-alkenyloxy)-4′-cyanobiphenyl mesogenic molecules to the vinyl groups which belong to the backbone, leading to a side-chain liquid-crystalline polysiloxane (SCLCP) which has its mesogens distributed regularly along the main chain. Preliminary measurements indicate an electro-optic switching time τs = 1 min at 20°C and 7 s at 32°C (dc, 5 V/μm).