Side-chain liquid-crystalline copolymers containing charge transfer groups

Abstract

A series of side-chain liquid crystal copolymers have been prepared based on a polystyrene backbone and having 4-nitro-4′-oxyazobenzenealkyloxy and 4-methoxy-4′-oxyazobenzenealkyloxy pendant groups. All the polymers exhibit solely smectic behaviour. The thermal stability of the smectic phase is significantly enhanced in the copolymers when compared to the homopolymers. This is compared to the behaviour of the analogous monomeric compounds. The enhancement of the thermal stability is attributed to a specific interaction, possibly charge transfer.