SIDE-CHAIN LIQUID-CRYSTALLINE ALTERNATING COPOLYMERS OF MESOGENIC MONOMERS - SYNTHESIS AND PROPERTIES

Seven new vinyl ether and fumarate monomers containing different mesog enic groups were synthesized and copolymerized to obtain three series of side-chain liquid crystalline copolymers. The free-radical copolyme rization of the monomers led to copolymers with nearly alternating str uctures, although a preferential incorporation of fumarate units was a lways observed. Alternating tendency and composition behavior of the c opolymers were interpreted in terms of a penultimate unit effect model . By appropriately adjusting the stoichiometry of the feed mixture, co polymers with a random distribution of mesogenic groups were also prep ared. Comparison of the nematic-to-isotropic transition temperature an d entropy (T(NI),DELTAS(NI)) of alternating copolymers revealed that t he randomization of mesogenic groups produces a moderate but definite increase in both the stability (T(NI)) and degree of order (DELTAS(NI) ) of the nematic mesophase.