Microphase-separated structure of telechelic urethane acrylate anionomers and their network in various solvents

Telechelic urethane acrylate anionomer (UAA) chain showed less viscosity an d polyelectrolyte behavior in water than dimethyl acetamide (DMAc) because of hydrophobic aggregation. UAA networks prepared in different solvents (wa ter and DMAc) exhibited very different swelling behaviors in the same swell ing medium, which can be interpreted as due to the very different microstru ctures formed in the solvents. UAA networks prepared with water (UAHG netwo rks) had microphase-separated hydrophilic and hydrophobic domains, whereas UAA networks synthesized with DMAc (UADG networks) had relatively homogeneo us network structures. The mechanical property of the UAHG and UADG network s, measured with a dynamic mechanical analyzer, was also very sensitive to the solvent type used during the crosslinking reaction. UAHG networks with a microphase-separated structure had a higher modulus than UADG networks. T he results of the mechanical property measurements showed that water was a much better solvent for the hydrophilic hard segments of UAA chain than DMA c, even though DMAc dissolved both hydrophilic and hydrophobic segments of UAA chain. (C) 2000 John Wiley & Sons, Inc.