title: Spectroscopic study on water diffusion in poly(ester urethane) block copolymer matrix.
abstract: The diffusion of water in a phase-separated biodegradable poly(ester urethane) shape-memory polymer with poly(epsilon-caprolactone) (PCL) as the soft segment was investigated using time-resolved FTIR-ATR. On the basis of the band fitting and water ordering in drawn films, the broad water band in the 3800-2800 cm(-1) region was decomposed into four bands located at 3620, 3510, 3400, and 3260 cm(-1), and the first two components at 3620 and 3510 cm(-1) were assigned to the vibrations of antisymmetric and symmetric stretching of water hydrogen bonded with the C=O group of the soft segment. The other two were associated with water bonded to the urethane hard segments in the forms of N-H:O-H:O=C bridge hydrogen bond and double hydrogen bonds with two C=O groups, respectively. Furthermore, band fitting and two-dimensional correlation analyses revealed that in the diffusion process, water first diffuses into the continuous soft-rich PCL phase and then into the hard-rich urethane domains, forming double hydrogen bonds with two C=O groups prior to the bridge hydrogen bond in the form of N-H:O-H:O=C.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, and Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun, 130022, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Jin
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Su
mesh_terms: D004058:Diffusion; D006860:Hydrogen Bonding; D011091:Polyesters / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D011091:Polyesters; D011140:Polyurethanes; C081821:microthane foam; D014867:Water; C016240:polycaprolactone