title: Effect of water vapor sorption on local structure of poly(vinylpyrrolidone).
abstract: The effect of water vapor sorption on the local structure of poly(vinylpyrrolidone) (PVP), was investigated using high-quality X-ray powder diffraction (XRPD). To examine the effects on molecular scale structure due to polymer chain length and water sorption, different molecular weights of PVP were studied at ambient temperature and different controlled relative humidities. Sorption of water determined gravimetrically on drying and changes to the glass-transition temperature (T(g)) measured by modulated differential scanning calorimetry (mDSC) were found to be consistent with previous reports. The XRPD results show that the position of the high- and low-angle halos for PVP change with the sorption of water. The corresponding characteristic scattering distances display a strong correlation with the measured water content and to T(g). Chemometric analysis was also performed to extract water content information from XRPD data and obtained results are correlated with the values measured gravimetrically, which lends support for the apparent clustering of water in PVP drawn by other techniques.
authors.affiliation: SSCI, a Division of Aptuit, 3065 Kent Avenue, West Lafayette, Indiana 47906, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Teng
authors.forename: Simon
authors.initials: S
authors.lastname: Bates
authors.forename: David A
authors.initials: DA
authors.lastname: Engers
authors.forename: Kevin
authors.initials: K
authors.lastname: Leach
authors.forename: Paul
authors.initials: P
authors.lastname: Schields
authors.forename: Yonglai
authors.initials: Y
authors.lastname: Yang
mesh_terms: D011205:Povidone / Q000737:chemistry*; D033362:Powder Diffraction; D013227:Steam; D044366:Transition Temperature; D014961:X-Ray Diffraction
chemical_list: D013227:Steam; D011205:Povidone