POLYURETHANE CATIONOMERS WITH PENDANT TRIMETHYLAMMONIUM GROUPS .1. FOURIER-TRANSFORM INFRARED TEMPERATURE STUDIES

Specific interactions are investigated in a series of polyether-polyurethane cationomers containing pendant trimethylammonium groups, with ion contents ranging from 0 to 0.88 mequiv/g, using Fourier transform infrared temperature studies. Hydrogen bonding of urethane N-H groups to urethane carbonyls, which has been extensively reported in conventional polyurethanes, is also evident in these materials. Additionally, the N-H stretching region shows significant contributions from N-H groups hydrogen bonded to ether oxygens of the soft segments in the homogeneous un-ionized polyurethane and to neutralizing anions in the cationomers. Spectral deconvolution and mass balances are used to obtain semiquantitative information on the extent of hydrogen bonding to the various proton accepters as a function of temperature. As the temperature of the un-ionized sample is increased from 30 to 140 degrees C, hydrogen bonding of N-H groups to polyether oxygens decreases, while hydrogen bonding to urethane carbonyls increases. A similar redistribution of N-H hydrogen bonds, from the anion to carbonyl groups with increasing temperature, is observed for the cationomers. The results for each polymer are related to its chemical structure, thermomechanical properties, and morphology.