In‐situ photopolymerization of oriented liquid‐crystalline acrylates, 4. Influence of a lateral methyl substituent on monomer and oriented polymer network properties of a mesogenic diacrylate

Abstract

AbstractMesomorphism and the molecular orientation of 1,4‐phenylene bis{4‐(6‐(acryloyloxy)hexyloxy)benzoate} (1) and its derivative with a methyl‐substituent in the central phenylene group (2) are studied. The methyl group affects the transition temperatures and the thermodynamic parameters, but not the order parameter of the monomers. The photoinitiated polymerization of the diacrylate monomers in their uniaxially oriented state leads to highly oriented and densely crosslinked polymer networks. The order parameter of these networks depends on the polymerization temperature, but becomes nearly temperature‐independent after polymerization. The presence of the methyl group leads to a significant lower degree of order in the polymeric state. In addition, data are presented on the monomeric viscosity of 2 and on the tensile moduli, glass transitions and refractive indices of the oriented polymer networks. In order to extend the mesomorphous temperature range, mixtures of 1 and 2 are also investigated.