ORIENTATIONAL DYNAMICS IN THE CRYSTALLINE AND AMORPHOUS STATES OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANE PROBED BY 2ND-HARMONIC GENERATION

The orientational behaviour of mesogenic chromophores in side-chain li quid crystalline polysiloxane subject to an external electric held was investigated by the measurement of second harmonic generation (SHG). The rise and decay rates of the electric-field-induced SHG intensity i n the crystalline state were found to be slower than those in the amor phous state; furthermore, the SHG intensity in the crystalline state w as found to be weaker than that in the amorphous state. Analysis of th e rise and decay rates of the electric-field-induced SHG intensity sug gested that the mesogenic chromophores in the amorphous state move ind ependently with other mesogenic chromophores and with the siloxane bac kbone, whereas those in the crystalline state move cooperatively with them. (C) 1998 Elsevier Science Ltd. All rights reserved.