| Abstract: | Amphiphilic urethane acrylate hydrogels containing ionic group (dimethylopropionic acid, DMPA) were prepared by varying the
molecular weight of the soft segment (polyether type, PTMG) and type of diisocyanate, and their swelling behaviors and mechanical
properties were examined. They showed amphiphilic property due to the hydrophilic ionic groups and hydrophobic polyethers
comprising the urethane acrylate network. Heterophasic gel structure could be found for the hydrogels prepared in water, but
not for the hydrogels in organic solvent (1,4-dioxane), through scanning electron microscopy. Because of this heterophasic
gel structure, they were able to take in a large amount of water as well. The hydrophobic interaction generated by the polyether
soft segments between urethane acrylate network chains decreased the degree of swelling, however, increased reversibly the
tensile strengths at equilibrium swelling state. MDI-based hydrogel showed low swelling ratio and high tensile strength because
of its ordered hard domain structure. These amphiphilic urethane acrylate hydrogels showed salt- and pH-dependent swelling
behaviors.
Received: 26 September 1997 Accepted: 24 December 1997 |
