Photopolymerization of lyotropic liquid crystalline systems: A new route to nanostructured materials

In recent years, a considerable amount of research has been dedicated to synthesizing highly ordered nanostructured materials. One way to achieve this is through templated polymerizations. A novel route to fabricating such materials is through the use of lyotropic liquid crystals (LLCs) that possess highly ordered nanostructures. However, LLC phases lack the necessary physical robustness. So, templating LLC phase morphology onto other materials such as organic polymers would give a nanostructure retained as part of a robust polymeric matrix. This study focuses on the photopolymerization behavior and structure retention of hydroxyethyl acrylate (HEA) / dodecyltrimethyl ammonium bromide (DTAB) / water system in a select LC phase. The results suggest that the polymerization behavior is heavily dependent on the type of LLC structure. Specifically, lamellar aggregates polymerize faster than either cubic or isotropic morphologies due to diffusional limitations on the growing polymer chain. Monomer segregation also plays a role in determining the polymerization rates. Results also indicate that the original LLC order of these systems is largely retained upon photopolymerization although some LLC phases do change upon cure. This order would be useful in applications such as ultrafiltration membranes, separation media, and drug delivery systems.