Electrorheological effect of liquid crystalline polymers

length and various terminal structures has been prepared and their electrorheological (ER) effect has been investigated. Although the LCP itself showed small ER effect, a mixture of the LCP with a plain polydimethylsiloxane (PDMS) oil was found to show a large increase in shear stress upon application of an electric field. The shear stresses under DC 2 kV/mm of an electric field were 14 to 4 times those without the application of an electric field over the temperature range of 30 to 160 degrees C for a 2:1 mixture (by weight) of a LCP containing an oxyethylene spacer and a mesogen based on 4-cyanophenyl benzoate with PDMS. Two mechanisms responsible for the generation of the ER effect was suggested from the investigation using phenyl-substituted PDMS and an analysis by DSC: oriented LC network induction, and phase separation between the LC base polymer and PDMS.