(670c) Fast Multi-Stimuli-Responsive Nanoporous Hydrogels Produced from Polymerization of Lyotropic Liquid Crystals

In this work, we present the synthesis of thermo- and pH-responsive nanoporous hydrogels through photopolymerization of lyotropic liquid crystals (LLCs) containing a thermoresponsive Poloxamer and a charged monomer such as acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid, and 2-(dimethylamino)ethyl methacrylate. LLCs with lamellar and normal hexagonal structure are used to synthesize the desired hydrogels. Cross-polarized light microscopy and small angle X-ray scattering are used to characterize the structures before and after reaction. The experimental results reveal that the polymerized LLCs (polyLLCs) can swell ~200%-500% in less than 100 s. Additionally, the swollen polyLLCs can lose up to 60 wt% of the absorbed water in less than 100 s when the temperature is increased from 10 to 65 °C or the pH is changed from neutral to acidic/basic conditions. The results show that both thermo- and pH-responsiveness of the synthesized nanoporous hydrogels are reversible for several cycles. We also show the possibility of tuning swelling kinetics, water uptake, compressive modulus, and temperature and pH sensitivity of the hydrogels through changing the LLC formulation.