Hydrogels are polymeric networks that are not soluble in water but instead swell in the presence of water. Because of this property, they have broad applications in the biomedical fields. Professor Christopher Hobbs' group at Texas A&M University-Kingsville explores new routes toward the preparation of functional hydrogels. Specially, his research group develops a highly efficient and precious metal-free reaction for the synthesis and modification of hydrogels. This project provides interdisciplinary research experience to many underrepresented undergraduate students, delivering a vital stepping stone toward careers in fields of science, technology, engineering, and mathematics (STEM). Additionally, Professor Hobbs organizes Polymer Chemistry Workshops, in which high school teachers learn methods and experiments that can be used to introduce aspects of polymer chemistry in their science classes in the hopes of recruiting a new, diverse generation of young students to STEM fields.
This project focuses on the utilization of a facile, catalyst-free substitution reaction between thiols and alpha-bromo esters for the preparation of a new class of hydrogels. The process employs thio-bromo substitution reactions to convert alpha-bromoester-containing polynorbornenes and poly(oxanorbornene)s to polymers with functionality (e.g., hydroxyl, amino, and ionic groups) known to instill water-swellability to macromolecular architectures. Cross-linking of the resulting polymers with dithiols produces a new class of hydrogels. While the preparation of alpha-bromoester-containing polynorbornenes and poly(oxanorbornene)s by Ring Opening Metathesis Polymerization (ROMP) requires the use of a ruthenium catalyst, the conversion of these polymers to hydrogels involves metal-free reactions that minimize the use of precious metals. With the support from the NSF Macromolecular, Supramolecular and Nanochemistry Program, Professor Hobbs' group conducts research to examine the effectiveness of this synthetic approach and the dependence of the hydrogel properties on the polymeric backbone, side chain groups, and cross-linker identity.
