Side chain liquid crystalline elastomers - II. Thermal properties and orientational behaviour of the LCE based on unsaturated copolyesters

The effect of crosslinking density on the phase behaviour of smectic liquid crystalline networks was studied; the results showed that crosslinking in their smectic phases can greatly enhance the stability of the liquid crysta lline phase. The higher the crosslinking density, the higher the smectic-is otropic transition temperature. The mechanically-induced orientation was st udied by polarized FTIR spectroscopy. The smectic liquid crystalline networ k could be oriented parallel to the mechanical field at higher draw ratio l ambda, while at lower lambda the mesogenic groups are oriented perpendicula r to the field for the networks with higher crosslinking density. The obser ved mechanically-induced orientation is interpreted by a proposed mechanism .