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Abstract
A system of non-centrosymmetric mesogens (4, nitrobenzylidene-2′-methylphenol(M2) and 4, cyanobenzylidene-2′-methylphenol(M5)) and their corresponding alkanol phenoxy ethers (M2C8 and M5C8) was investigated. The mesomorphic properties of mixtures of these low molecular mass compounds were established. The properties of homo and random copolymers of M2 and M5 attached as side-groups via a C8 spacer to a poly(methyl methacrylate) backbone were studied. A phase diagram was obtained. The thermo-mechanical relaxation properties of this system were also investigated by means of thermo-stimulated currents. While monotropic namatic mesophases dominate the low molecular mass M2C8-M5C8 system, the copolymers display an enantiotropic nematic behaviour. Two relaxation processes dominate the thermomechanical response of this copolymer system. One is interpreted as related to the segmental motion of the backbone (α-peak), the second, to the motion of the mesogenic groups (δ-peak). While the parameters related to the alpha peak relaxation such as the activation energy or relaxation times are not strongly affected by copolymer composition, the delta relaxation is affected by the composition of the copolymer.