HYBRID LIQUID-CRYSTALLINE BLOCK-COPOLYMERS .2. X-RAY-DIFFRACTION ANALYSIS OF POLYESTER-POLYMETHACRYLATE BLOCK-COPOLYMERS

The molecular organization in the smectic mesophases of a series of ma in-chain/side-chain block copolymers was studied by X-ray diffraction on oriented specimens. The main-chain and the side-chain blocks were p hase-separated and gave rise to two coexisting smectic domains with di fferent layer periodicities. The orientation of the smectic planes in the distinct domains with respect to the fiber axis was very different in the various samples and depended on the relative length of the blo cks. In the presence of relatively short side-chain blocks, the orient ation of the main-chain block dominated and the smectic planes of the side-chain block were forced to be parallel to those of the main-chain block and perpendicular to the fiber axis. In contrast, when the side -chain block was sufficiently long it imposed its own orientation to t he main-chain block. In this case, the smectic planes of the main-chai n block were oriented parallel to those of the side-chain block and to the fiber axis.