title: Relaxation phenomena in poly(vinyl alcohol)/fumed silica affected by interfacial water.
abstract: Interaction of poly(vinyl alcohol) (PVA) with fumed silica was investigated in the gas phase and aqueous media using adsorption, broadband dielectric relaxation spectroscopy (DRS), thermally stimulated depolarization current (TSDC), infrared spectroscopy, thermal analysis, and one-pass temperature-programmed desorption (OPTPD) mass-spectrometry (MS) methods. PVA monolayer formation leads to certain textural changes in the system (after suspension and drying) because of strong hydrogen bonding of the polymer molecules to silica nanoparticles preventing strong interaction between silica particles themselves. This strong interaction promotes associative desorption of water molecules at lower temperatures than in the case of silica alone. Interaction of PVA with silica and residual water leads to depression of glass transition temperature (T(g)). There are three types of dipolar relaxations at temperatures lower and higher than the T(g) value. A small amount of adsorbed water leads to significant conductivity with elevating temperature.
authors.affiliation: Institute of Surface Chemistry, 17 General Naumov Street, Kiev 03164, Ukraine. gun@voliacable.com
authors.forename: V M
authors.initials: VM
authors.lastname: Gun'ko
authors.forename: P
authors.initials: P
authors.lastname: Pissis
authors.forename: A
authors.initials: A
authors.lastname: Spanoudaki
authors.forename: V I
authors.initials: VI
authors.lastname: Zarko
authors.forename: Y M
authors.initials: YM
authors.lastname: Nychiporuk
authors.forename: L S
authors.initials: LS
authors.lastname: Andriyko
authors.forename: E V
authors.initials: EV
authors.lastname: Goncharuk
authors.forename: R
authors.initials: R
authors.lastname: Leboda
authors.forename: J
authors.initials: J
authors.lastname: Skubiszewska-Zieba
authors.forename: V D
authors.initials: VD
authors.lastname: Osovskii
authors.forename: Y G
authors.initials: YG
authors.lastname: Ptushinskii
mesh_terms: D000327:Adsorption; D006860:Hydrogen Bonding; D013058:Mass Spectrometry; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D012822:Silicon Dioxide; D011142:Polyvinyl Alcohol