Electrorheological properties of liquid-crystalline materials containing liquid-crystalline polymer of various molecular weights and spacer lengths

Polymers with cyanobiphenyl groups (PCBAn) in their side-chains with differ ent spacer lengths (n=2,6,11) and different molecular weights: (Mw), were p repared. The phase behavior of the polymers and that of liquid-crystalline mixtures (LCMn) consisting of PCBAn and low-molecular-weight liquid crystal , were observed. LCM2 and LCM6 showed liquid-crystalline property of nemati c phase, while LCM11 showed liquid-crystalline property of smectic phase. T he electrorheological properties of LCMn were investigated. The viscosity o f LCMn increased upon application of a DC electric field, and the degree of increase was characteristic to each n value. LCM6 of different Mw showed n early the same electrorheological behavior except for the LCM6 of lowest Mw , which displayed a large increase in viscosity upon application of the ele ctric field.