Comparison of hydrogen bonding in polydimethylsiloxane and polyether basedurethane and urea copolymers

Hydrogen bonding in polydimethylsiloxane and polyether based urethane and u rea type segmented copolymers was investigated by infrared spectroscopy, di fferential scanning calorimetry and quantum mechanical calculations. Hydrog en bonding in model urethane and urea compounds was compared with those of the copolymers, in order to determine the extent of interaction and resulti ng phase mixing between hard and soft segments in these copolymers. Quantum mechanical calculations were also used to determine the interaction energi es due to hydrogen bonding in model urethane and urea compounds. Further, s imilar calculations were also performed to quantify the interactions betwee n silicone and ether type soft segments, and urea and urethane type hard se gments. As expected, these calculations clearly indicated the absence of an y interaction between silicones and urea groups, while there was substantia l hydrogen bonding between urea groups and the oxygen in the ether type sof t segments. Results of FTIR studies and quantum mechanical calculations wer e in good agreement with thermomechanical behavior and mechanical propertie s of these copolymers. (C) 1999 Elsevier Science Ltd. All rights reserved.