Novel amphiphilic polyurethane networks: gelation mechanism and swelling behaviors

Abstract

Amphiphilic polyurethane gels can be prepared using poly(ethylene glycol)-modified urethane acrylate (PMUA) through two types of methods. When PMUA gels were prepared at an aqueous phase, droplet coalescence and gelation occurred at the same time, so the microstructure of these gels (UAHG) was similar to that of PMUA emulsion which was formed by the microphase separation between hydrophilic and hydrophobic domains. In the case of UAHG gels, as the composition ratio of water to PMUA increased, swelling in water increased, but swelling in dioxane was slightly decreased. For the other kind of PMUA gels prepared using dioxane through a conventional gelation process (UADG), swelling in dioxane greatly increased with increasing of the composition ratio of dioxane; however, swelling of these gels in water was very low. The difference in swelling behavior between UAHG and UADG gels was due to the difference of microstructures between these gels which also influenced the mechanical properties. Additionally, the microstructures of UADG and UAHG gels were able to be confirmed using scanning electron microscopy (SEM) and contact angle measurement. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 821-832, 1997