Control of Cross-Linking Polymerization Kinetics and Polymer Aggregated Structure in Polymer-Stabilized Liquid Crystalline Blue Phases

Kinetics of cross-linking copolymerization of acrylate- and methacrylate-monomers in a liquid crystal blue phase to prepare the polymer-stabilized blue phase were investigated based on dynamic mechanical analysis. Although the polymerization rate of methacrylate-monomers is generally much lower than that of acrylate-ones, we found that a methacrylate cross-linker enhanced the cross-linking copolymerization and an acrylate one suppressed it when acrylate- and methacrylate-monomers were copolymerized with cross-linking. The order of copolymerization rate of monofunctional monomer/difunctional one was monoacrylate (mA)/dimethacrylate (dMA), mA/diacrylate (dA), monomethacrylate (mMA)/dMA, and mMA/dA. The synchrotron small-angle X-ray scattering measurements were carried out to evaluate the aggregated structure of polymer networks in the polymer-stabilized blue phase and found the regular polymer structure corresponding to the disclination lattice of the blue phase, indicating that the polymers were segregated preferentially in the disclination cores. The degree of the regularity of polymer networks was opposite order of copolymerization rate. We obtained a good correlation among the polymerization kinetics, the mechanical elastic constant and the polymer aggregation structure in the polymer-stabilized blue phases, leading to a novel strategy to control the structure and the performance of the polymer-stabilized blue phases.