MESOPHASE STRUCTURE AND ALIGNMENT UNDER DIFFERENT FIELDS OF LIQUID-CRYSTALLINE MAIN-CHAIN SIDE-GROUP BLOCK-COPOLYMERS/

Liquid crystalline block copolymers are new materials in which multipl e molecular interactions can provide the driving force for complex pha se behaviors and states of order. Block copolymers containing both liq uid crystalline main-chain polyester and side-group polymethacrylate b locks were investigated. They phase separated in the liquid crystallin e state and their individual mesophases coexisted. The copolymers resp onded very differently when either a mechanical or a magnetic field wa s used for alignment. In the fibers the orientations of the side-group and main-chain smectic planes with respect to the fiber axis depended critically on the block lengths and on their distinct tendencies to a lign, whereas under a magnetic field the mesogens aligned collectively with their long molecular axis parallel to the field, independent of the copolymer structure.