Side-group liquid crystal copolymers containing nonmesogenic units: Dependence of the thermal behaviour upon composition

The synthesis and properties of a new mesogenic/nonmesogenic copolymer syst em, namely the poly [6-(4'-methoxyazobenzene-4'-oxy)hexyl methacrylate]-co- poly[methyl methacry late]s, are described. Copolymers containing 0.59 or g reater mol fraction of the mesogenic side-groups exhibit nematic behaviour while those containing 0.39 or less mol fraction mesogen are amorphous. The glass transition temperatures exhibit a negative deviation from linear beh aviour on varying the copolymer composition. In contrast, the nematic-isotr opic transition temperatures decrease in an essentially linear fashion on i ncreasing the nonmesogen content, This behaviour is compared with that of a smectogenic series and differences are accounted for in terms of a microph ase separated smectic phase.