Gel Formation in Urethane Liquid Oligomers

The phenomenon of gel formation is ubiquitous for various materials including polymer solutions, ionomers, biomaterials, and consumer household products. Developing a physical understanding of the interactions that lead to gel formation is essential for rational material design, and controlling the gel formation characteristics is a topic of significant interest. We have investigated a physical gel formed in a urethane oligomer system dispersed in an organic solvent. The mechanism of gel formation was investigated by rheology, polarized optical microscopy and FTIR. We find evidence of hydrogen bonding and ordered structure formation in the gel. Additionally, a rheology-based technique was developed to predict the gel formation characteristics.