Synthesis and photoinitiated polymerization of liquid crystalline diepoxides

Four different liquid crystalline diepoxides were synthesized. Replacement of a methylene group by an oxygen atom in the spacer segment of the molecule decreased the thermal stability of the mesophase. In order to produce highly anisotropic networks, these compounds were cationically photopolymerized in the nematic phase. Differential scanning calorimetry and Fourier transform infra-red were used to monitor the polymerization. The degrees of conversion calculated from both techniques were in good agreement with each other. The replacement of a methylene group by an oxygen atom in the spacer part of the molecule also increased the rate of the polymerization reaction. Post-curing was sometimes necessary to produce highly stable networks. Furthermore, some results suggest that liquid crystalline nematic ordering increases the polymerization rate.