Polymer Bulletin 36, 737-744 (1996) Polymer Bulletin 9 Springer-Verlag 1996 Swelling behavior of novel polyurethane hydro-xerogels Ju-Young Kiln, Kyung-Do Sub* Department of Industrial Chemistry, College of Engineering, Hanyang University, Seoul 133-791, Korea Received: 26 December 1995/Revisedversion: 20 February 1996/Accepted:27 February 1996 SUMMARY Polyurethane hydro-xerogels derived from PEG-modified urethane acrylates (PMUA), containing hydrophilic segment (polyoxyethylene groups) and hydrophobie segment at the same molecule, were prepared and their swelling behaviors were evaluated. Hydro-xerogels of PMUA were prepared using gelation process of PMUA emulsions. these gels could be swelled at both of water and dioxane, moreover, the swelling ratio of these gels at dioxane and water were changed with composition ratio of water to PMUA in the preparation of gel. In aqueous medium, swelling ratio of these gels increased with the increase in composition ratio of water to PMUA. However, in organic medium (Dioxane), swelling ratio decreased as the composition ratio of water increased. Additionally, as the reaction molar ratio of PEG to 2-HEMA increased, swelling ratio of gels at water increased. These results were due to microstructure of PMUA gels, which was formed by phase separation between hydrophilic and hydrophobic segments in the course of gelation. INTRODUCTION Polyurethane hydrogels are claimed to have applications in the biomedical area as a contact lens and surgical implants. Gould and Johnston prepared the interpenetrating network of polyurethane and diacrylates in the presence of hydrophilic polyurethane. Additionally, Lai and Baccei prepared polyurethane hydrogel by UV curing of mixture comprised ofhydrophobic urethane diacrylate and hydrophilic monomers (I-4). However, in this study, we intended to prepare a novel polyurethane gel using PEG- modified urethane acrylate (PMUA) containing hydrophilic segment (polyoxyethylene groups) and hydrophobic segment at the same molecule, which was used as a core polymer of impact modifier for PMMA and epoxy resin in our previous experiment (5-6). Additionally, this resin could be formulated and emulsified to be used as a water dispersible UV curable formulation (7). PMUA shows phase separation behavior in the process of emulsification, that is, the hydrophilic segment (polyoxyethylene group) became orient to water phase and the hydrophobic segment comprised of vinyl groups and hydrocarbon chains became * Corresponding author