HYDROGEN-BONDING BETWEEN URETHANE AND UREA - BAND ASSIGNMENT FOR THE CARBONYL REGION OF FTIR SPECTRUM

A model urethane compound and a model urea compound as viscous liquids at room temperature were synthesized. Mixtures of the two model compo unds were used as the model systems of poly(urethane urea). The C=O ab sorption bands of the mixtures were assigned by using several infra-re d techniques such as spectrum addition, spectrum subtraction and secon d derivative spectroscopy. Infra-red spectra of the mixtures showed th e band of the free urethane carbonyl at 1732 cm(-1), the band of disor dered urea carbonyl at 1666 cm(-1) and a new band at 1698 cm(-1) in th e carbonyl region. The band at 1698 cm(-1) between that from hydrogen- bonded urethane C=O (1710 cm(-1)) and the band of free urea C=O (1694 cm(-1)) was assigned to hydrogen bonding between the urethane carbonyl and the urea N-H. Copyright (C) 1996 Elsevier Science Ltd.