2-COMPONENT DIACRYLATE NETWORKS FROM LIQUID-CRYSTALLINE AND NON-LIQUID-CRYSTALLINE MONOMERS .1. SYNTHESIS OF THE MONOMERS, PHASE-BEHAVIOR OF THE BINARY MONOMER MIXTURES, NETWORK FORMATION

Two-component networks of diacrylate monomers were synthesized by phot oinduced polymerization in the isotropic phase. In all systems one com ponent was a liquid-crystalline diacrylate, whereas the second compone nt was a non-liquid-crystalline diacrylate, which was varied in size, geometry and polarity. The phase behaviour of the monomer mixtures has been analysed by differential scanning calorimetry (DSC). It is influ enced by the melting point and the structure of the non-liquid-crystal line component. All samples were cross-linked in the isotropic phase 1 0 degrees C above the phase transition temperature and a modified diff erential scanning calorimeter was used to investigate the enthalpies o f photopolymerization. The final value and the time dependence of the conversion of acrylate double bonds were calculated from the DSC curve s. The final degree of conversion of the acrylate double bonds was bet ween 53 and 71% for all samples, whereas no significant dependence of the degree of conversion on the chemical structure of the monomers or the reaction temperature has been found. In contrast, the time depende nce of the conversion was influenced by the chemical structure of the non-liquid-crystalline component.