THERMOPHYSICAL STUDY OF THE LIQUID-CRYSTALLINE BEHAVIOR OF POLYSILOXANES WITH PENDANT PHOTOREACTIVE GROUPS CONNECTED THROUGH A DIMETHYLSILYL SPACER

A thermophysical study including microscopic, calorimetric and diffrac tometric analyses was undertaken in order to rationalize the photochem ical behaviour of some silicone copolymers containing cyanostyrylacryl ic side-groups connected to the main chain through a dimethylsilyl spa cer. An oligomeric analogue was also studied. This model compound exhi bits a smectic phase. The functional polysiloxane shows the phase sepa ration yielding microdomains containing the photoreactive side-groups dispersed in a silicone-rich phase containing the dimethylsiloxane seg ments of the main chain. The photosensitive esters are gathered in the ordered microdomains exhibiting a smectic character. Several observat ions based on the bulk state photochemistry indeed showed a reactivity similar to the behaviour observed with the crystalline low molecular weight analogues.