Hydrophilic Polymeric Adhesives: A Case Study

Abstract

Hydrophilic polymers are key components used in a variety of applications includingtissue adhesives, coatings for marine vessels, contact lenses, and drug delivery systems. The ability to use hydrophilic polymers across this spectrum of applications is related, in part, to the opportunity to tune the composition to meet diverse structure and property requirements. As an example, dental adhesives use a combination of hydrophilic and hydrophobic monomers to provide polymers for the repair of damaged tissue, i.e., enamel and dentin. The ratio of hydrophilic and hydrophobic monomers is especially critical since hydrophilicity allows the adhesive to integrate with wet substrates but may leave the adhesive vulnerable to structural degradation due to hydrolytic degradation. The incorporation of the monomer 3- (Trimethoxysilyl)propyl methacrylate (MPS) can theoretically mitigate hydrolytic degradation by creating additional covalent cross links via hydrolysis-condensation reactions. The objective of this work was to determine the gelation process of hydrophilic polymers containing MPS at varying concentrations. Rheology experiments were planned, but these investigations could not be completed since the lab was shutdown to protect researchers during the COVID-19 pandemic. The investigation was limited to thermal properties and water sorption of polymers with MPS concentrations ranging from 0 to 10 wt% (5.9 mol%). The results revealed statistically significant differences in water sorption and swelling as a function of the MPS concentration. Further analysis revealed that factors such as hydrophilicity, cross-linking density, and solubility contributed to these differences with hydrophilicity playing a dominant role. Future studies should explore the role of MPS in the gelation and durability of formulation in polar solvents.