title: Interactions of poly(dimethylsiloxane) with nanosilica and silica gel upon cooling-heating.
abstract: To control the properties of poly(dimethylsiloxane) (PDMS, Oxane 1000) as a bio-inert material, the characteristics of Oxane 1000 were compared for PDMS alone and interacting with silica gel Si-100 and nanosilica PS400. Low-temperature (1)H NMR spectroscopy, applied to static samples at 200-300 K, and differential scanning calorimetry (DSC) at 153-393 K were used to analyze the properties of PDMS and composites. The NMR study shows that liquid and solid-like fractions of PDMS co-exist over a broad temperature range. The cooling-heating cycles give hysteresis loops of intensity of (1)H NMR signals of methyl groups of a liquid fraction of PDMS vs. temperature depending on the silica type. The loop width differs for PDMS alone and bound to silicas, and the samples preheated at 420 K are characterized by much narrower loops. DSC measurements of the samples show a significant difference in the thermograms on the first and second DSC scans that depend on the silica type. For PDMS confined in pores of silica gel, 3D spatial structure of the polymers can be more ordered than that of PDMS located in thin layers at a surface of nanosilica. Therefore, both melting endotherms and crystallization exotherms are observed for PDMS/silica gel. However, for PDMS/nanosilica, both thermal features are much weaker and observed during only the first DSC scan.
authors.affiliation: Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kiev, Ukraine. Electronic address: vlad_gunko@ukr.net.
authors.forename: V M
authors.initials: VM
authors.lastname: Gun'ko
authors.affiliation: Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kiev, Ukraine.
authors.forename: V V
authors.initials: VV
authors.lastname: Turov
authors.affiliation: Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kiev, Ukraine.
authors.forename: A A
authors.initials: AA
authors.lastname: Turova
authors.affiliation: Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kiev, Ukraine.
authors.forename: T V
authors.initials: TV
authors.lastname: Krupska
authors.affiliation: Department of Physics, National Technical University of Athens, 15780 Athens, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Pissis
authors.affiliation: Faculty of Chemistry, Maria Curie-Skłodowska University, 20-031 Lublin, Poland.
authors.forename: R
authors.initials: R
authors.lastname: Leboda
authors.affiliation: Faculty of Chemistry, Maria Curie-Skłodowska University, 20-031 Lublin, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Skubiszewska-Zięba
mesh_terms: D002152:Calorimetry, Differential Scanning; D003080:Cold Temperature; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D006358:Hot Temperature; D049329:Nanostructures; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004129:Dimethylpolysiloxanes; C013830:baysilon; D012822:Silicon Dioxide
keywords: Adsorption effects; Confined space effects; DSC; Low-temperature (1)H NMR spectroscopy; PDMS/nanosilica; PDMS/silica gel; Poly(dimethylsiloxane)