Abstract
Three samples of a main-chain liquid-crystalline elastomer, which are prepared by photo-cross-linking at the SmC*, at the SmA, and at the Iso phases, respectively, are analyzed in order to investigate an effect of molecular alignment at the cross-linking reaction on the phase transformational behavior. The successive SmC*-SmA-Iso transitions are observed in the SmC*-crosslinked-elastomer, and spontaneous twist deformation caused by the unwinding of helix occurs just above the SmC*-to-SmA transition temperature. Only an orthogonal alignment due to the SmA phase, namely no SmC* phase, is confirmed in the SmA-crosslinked-elastomer, in which elongation and shrinkage along to the layer normal take place around the SmA-to-Iso transition temperature. As for the Iso-crosslinked-elastomer, no smectic phase appears in the whole temperature range observed. These results indicate that the phase transformational behavior of the liquid-crystalline elastomer is dominated by the molecular alignment at the cross-linking reaction.
