Physical Behavior of Cross-Linked PEG Hydrogels Photopolymerized within Nanostructured Lyotropic Liquid Crystalline Templates

Abstract

While hydrogels exhibit numerous characteristics that make them ideal in biological applications, they are typically limited in overall design flexibility due to the rigid dependence of their physical properties and behavior on the chemistry and cross-linking structure of the gel's network. As the demand for hydrogels with precisely engineered properties grows, nanotechnology may provide a means through which to circumvent the inherent drawbacks of hydrogel systems to form unique, highly advanced materials with enhanced properties. In this work, self-assembling nanostructured lyotropic liquid crystalline (LLC) mesophases were used as polymerization templates, directing the formation of highly cross-linked PEGDA hydrogels. A 3-fold increase in both the compressive modulus and diffusive transport is realized in the PEGDA gel as the parent LLC mesophase, and thus the resulting structure of the hydrogel matrix is changed from a low ordered morphology to a system with a high degree of order and geometry. Additionally, the LLC templated hydrogels exhibited unique property relationships, including simultaneous increases in both the water absorptivity and the modulus of the material, behavior that is not observed in nontemplated, traditional PEGDA gels. The results of this study demonstrate that direct control over the physical properties of a cross-linked hydrogel material can be achieved simply by changing the degree of order and geometry imposed on the forming network using nanostructured LLC templates.