The effects of the mesogenic unit-deficient mers and of the mers containing potential mesogenic units
on mesophase transitions in comb-like liquid crystal polymers
Polimery 1997, No 7-8, 470
4-(6-hexyloxy)-4'-methoxyazobenzene 6-acrylate and 4-(6-hexyloxy) benzoate-4'-methoxyphenyl 6-acrylate were synthesized, polymerized and copolymerized to yield the corresponding homo and copolymers containing 25, 50 and 75 mole % of n-decyl methacrylate. Each polymer obtained exhibited liquid crystal properties although the starting monomers had none. This "polymer effect” was partly approached in terms of the energy of molecular interactions that are closely related to the packing density which in crystal monomers is much greater than in atactic and thus also amorphous polymers. The resulting polymers had glass transition temperatures (Tg) much lower than the melting points (Tm) of the corresponding monomers. Therefore, within the Tg—Tm interval, mesogenic units can be more mobile and more likely to produce liquid crystal domains in the polymers, where as in the monomers they would remain immobilized in the crystal lattice. The liquid crystal properties revealed by the copolymers containing as much as 75% of n-decyl methacrylate appear to be explicable in terms of agglomeration (microseparation) of aromatic mesogenic units in the polymer matrix of the aliphatic spacers.