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Full-Text Articles in Physical Sciences and Mathematics
Dynamics Of Adsorbed Poly(Methyl Acrylate) And Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Wuu-Yung Lin, Crystal E. Porter
Dynamics Of Adsorbed Poly(Methyl Acrylate) And Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Wuu-Yung Lin, Crystal E. Porter
Chemistry Faculty Research & Creative Works
Deuterium NMR and modulated differential scanning calorimetry (MDSC) were used to probe the behavior of ultrathin adsorbed poly(methyl acrylate) (PMA). The spectra for the bulk methyl-labeled PMA-d3 were consistent with the motions of the polymer segments being spatially homogeneous. For the polymers adsorbed on silica, multicomponent line shapes were observed. The segmental mobility of the surface polymers increased with increased adsorbed amounts. In contrast to the behavior of the polymers in bulk, the adsorbed lower-molecular-mass PMA-d3 was less mobile than the adsorbed high-molecular-mass polymer. The presence of a polymer overlayer was sufficient to suppress the enhanced mobility of the more-mobile …
Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor
Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor
Materials Science and Engineering Faculty Research & Creative Works
We have recently completed a series of experiments on methyl-labeled poly(vinyl acetate)-d3, (PVAc-d3)1 and poly(methyl acrylate)-d3 (PMA-d3).234 the systems have been studied as a function of the adsorbed amount, molecular weight, and presence of a protonated overlayer. Using deuterium line shape analysis, we have found that around the glass transition temperature, the adsorbed polymers show the presence of a motional gradient. Polymer segments near the silica-polymer interface have less mobility than the bulk polymer and those near the polymer-air interface are more mobile than those of the bulk polymer. A schematic representation of the motional gradient is shown in Figure …
Deuterium Nmr Studies Of Bulk And Silica-Absorbed Polystyrene, Macduff O. Okuom, Jinhua Yang, Frank D. Blum
Deuterium Nmr Studies Of Bulk And Silica-Absorbed Polystyrene, Macduff O. Okuom, Jinhua Yang, Frank D. Blum
Chemistry Faculty Research & Creative Works
Thin polymer films are used in applications such as electronics, biomedical devices and coatings. As the trend to make the devices smaller continues, a film's influence on a material's overall properties becomes more prominent. Previous studies have shown that thin polymer films have characteristics slightly different from those of bulk polymers. Film behavior has been characterized by examining thermal expansion, diffusion, conformation, density and glass transitions. The dynamics of glassy polystyrene has been investigated using a wide variety of theoretical and experimental methods. Schaefer et al., using 13C NMR, reported that ~7% of phenyl rings in polystyrene undergo -flips. Using …
Ft-Ir Studies Of Stereo Regular Pmma On Silica: Drying Effects, Bing Zhang, Suntree Kulkeratiyut, Suriyaphongse Kulkeratiyut, Frank D. Blum
Ft-Ir Studies Of Stereo Regular Pmma On Silica: Drying Effects, Bing Zhang, Suntree Kulkeratiyut, Suriyaphongse Kulkeratiyut, Frank D. Blum
Chemistry Faculty Research & Creative Works
A great amount of work has been done on the configuration of surface adsorbed poly(methyl methacrylate) (PMMA), especially on surfaces to which they have a strong attraction. Some studies have been make on the relationships between configuration and tacticity, molecular weight, adsorbed amount, and density of surface hydroxyl groups. The effect of tacticity on the conformation of alumina-adsorbed PMMA in solution and dry spin-coated films were studied by Grohen et al. Their results showed that surface-adsorbed PMMA chains adopted a relatively flat configuration, but iso-PMMA (isotactic) adsorbed on aluminum, with a much larger fraction of the bound carbonyl groups, had …
Molecular Mass And Dynamics In Pma-D₃ In The Glass Transition Region, Burak Metin, Frank D. Blum
Molecular Mass And Dynamics In Pma-D₃ In The Glass Transition Region, Burak Metin, Frank D. Blum
Chemistry Faculty Research & Creative Works
The segmental dynamics through the glass transition region, by which the glassy polymer becomes rubbery, are not well understood. Free volume, thermodynamic and kinetic theories have been used to describe the phenomenon behind the glass transition and some of those theories were tested with computer simulations. Different experimental techniques, such as NMR, thermo-mechanical analysis (TMA), differential scanning calorimetry (DSC), dilatometry and dynamic mechanical analysis (DMA) have all been also used to probe this important phenomena. Deuterium (2H) NMR has been a valuable tool for the investigation of the dynamics of macromolecules. Deuteration of macromolecules at specific locations on the chains …