AN INVESTIGATION OF THE SMECTIC-ISOTROPIC TRANSITION IN A SIDE-CHAIN LIQUID-CRYSTAL POLYMER BY SYNCHROTRON RADIATION X-RAY-DIFFRACTION

In this work we have used synchrotron x-radiation diffraction to follo w in real-time the isotropic-smectic phase transition of a side-chain liquid crystalline polymer. The analysis of the x-ray data indicated t hat the transition occurs within a very narrow biphasic region. As the transition takes place, the size of the smectic regions, as indicated by the width of the diffraction peaks, changed only very slightly bef ore impingement, suggesting a two-dimensional growth pattern. A therma l investigation of the polymer paralleling the x-ray experiments was u ndertaken and a kinetic analysis applied to the resulting data. Qualit ative agreement with a disk-like growth of the smectic regions was fou nd. We have shown that the overall kinetics of the isotropic-smectic t ransition of a side-chain polymer can be studied by x-ray diffraction permitting the evaluation of several structural parameters.