Journal of Polymer Science Part A: Polymer Chemistry, Vol.37, No.14, 2391-2399, 1999
Synthesis and mesomorphic behavior of a new series of side-chain liquid crystalline polymethacrylates bearing 2,6-naphthylene-based mesogen
A new homologous series of liquid crystalline (LC) polymethacrylates, the poly[omega-(2-phenoxycarbonyl-naphthalene-6-yloxy)alkyl methacrylate]s, in which the length of the alkyl spacer is varied between 3 and 12 methylene units, have been synthesized by free-radical polymerization. The prepared polymers were studied by IR and H-1-NMR spectroscopy, viscosity measurements, differential scanning calorimetry (DSC), and polarized microscopy. Polymers with 3 or 4 methylene units spacer were glassy in nature, whereas those with 5-12 methylene units spacer exhibited smectic behavior. The glass transition temperatures decrease on increasing spacer length. The isotropization temperatures and the corresponding transition entropies showed an odd-even effect, with the odd members exhibiting the higher values. This effect attenuates on increasing spacer length.
Keywords:side-chain liquid crystalline polymers;liquid crystalline polymethacrylates;mesogenic units;6-hydroxy-2-naphthoic acid;odd-even effect