G. Galli et al., MESOPHASE STRUCTURE AND ALIGNMENT UNDER DIFFERENT FIELDS OF LIQUID-CRYSTALLINE MAIN-CHAIN SIDE-GROUP BLOCK-COPOLYMERS/, Macromolecular symposia, 121, 1997, pp. 235-244
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.