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

Specific interactions are investigated in a series of polyether-polyur ethane cationomers containing pendant trimethylammonium groups, with i on contents ranging from 0 to 0.88 mequiv/g, using Fourier transform i nfrared temperature studies. Hydrogen bonding of urethane N-H groups t o urethane carbonyls, which has been extensively reported in conventio nal polyurethanes, is also evident in these materials. Additionally, t he N-H stretching region shows significant contributions from N-H grou ps hydrogen bonded to ether oxygens of the soft segments in the homoge neous un-ionized polyurethane and to neutralizing anions in the cation omers. Spectral deconvolution and mass balances are used to obtain sem iquantitative information on the extent of hydrogen bonding to the var ious proton accepters as a function of temperature. As the temperature of the un-ionized sample is increased from 30 to 140 degrees C, hydro gen bonding of N-H groups to polyether oxygens decreases, while hydrog en bonding to urethane carbonyls increases. A similar redistribution o f N-H hydrogen bonds, from the anion to carbonyl groups with increasin g temperature, is observed for the cationomers. The results for each p olymer are related to its chemical structure, thermomechanical propert ies, and morphology.