A new route for the preparation of liquid crystalline polyorganosiloxanes containing laterally linked mesogenic units on the main chains

Abstract

A new route for the preparation of liquid crystalline polyorganosiloxanes containing laterally linked mesogenic units on the main chains (LLM-POS) is described. First, a novel polyorganosiloxane containing hydroquinone units on the main chains (HQ-POS) was synthesized by hydrosilylation polymerization. To avoid the oxygen silylation side reaction of phenolic groups, tetrahydropyranyl (THP) protective groups were used on the phenols taking part in the hydrosilylation reaction, the results indicating that THP groups are very stable and effective in hydrosilylation reactions. Then HQ-POS was further modified by a grafting reaction with 4-n-octyloxybenzoyl chloride, giving the desired LLM-POS, which has an increased molecular mass in comparison with similar polymers prepared by commonly used approaches. The titled LLM-POS was characterized by DSC, POM and XRD and shown to give smectic textures.