Hydrogen bonding between poly(methyl vinyl ether-co-maleic acid) (PMVE-MA) and poly(vinyl alcohol) (PVOH) has resulted in films with lower oxygen transmission rates (OTR) than pure PVOH. In the range 20-30% (w/w) PMVE-MA, complexation between the two polymers in the blend was maximized, as shown by viscometry, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analysis. OTR measurements have shown that the maximum interpolymer complexation ratio also correlates with the lowest OTR values of the resulting film. The improved oxygen barrier properties are believed to be a combination of the relatively intact PVOH crystalline regions as shown with X-ray diffraction (XRD) and a higher degree of hydrogen bonding in the amorphous regions of the PVOH and PMVE-MA films as indicated by glass transition temperature (Tg) shifts. This leads to denser amorphous regions that reduces the rate of gases diffusing through the polymer film, hence the reduced OTR. 相似文献
The studies on the mechanism and kinetics of formation of a polymer layer on metallic cathodes by electropolymerization of acrylamide, formaldehyde, and N-methylolacrylamide in an aqueous environment are reviewed. A model for the formation of a supramolecular structure of films is described. The coating growth occurs in conditions of continuous synthesis of high- and low-molecular-weight polymer fractions. Removing low-molecular-weight products out of the film results in the formation of a porous structure. The orientation of monomer molecules and growing macrochains along the electric-field lines leads to a perpendicular arrangement of pores and channels with respect to the film surface and to the formation of an ordered crystalline phase of the polymer. The synthesized films exhibit an asymmetric three-layered structure, whose dense barrier layer forms at the metal/polymer film interface. The polymer comprises crystalline and amorphous phases. 相似文献
The process of micro- and nanolayer coextrusion of polymeric systems with good layer uniformity is described. Coextrusion through a series of layer multiplying die elements has enabled the production of films containing tens to thousands of layers with individual layer thicknesses from the micro- to the nanoscale. Improvements in layer uniformity are discussed through optimization of layer multiplier die design, selection of viscosity matched polymer systems, and incorporation of surface layer capabilities. Design of ‘uneven’ split layer multiplication dies has enabled the coextrusion of layered films with a wide variety of layer thickness distributions having up to a 10× difference in the individual film layer thicknesses. Coextrusion of layered polymer films with individual layer thicknesses down to the nanoscale has resulted in the production of novel systems with improved properties. Nanolayered polymer films were utilized to develop an all-plastic polymer laser, to fabricate gradient refractive index lenses, and to investigate gas barrier enhancement of crystalline polymer nanolayers confined to induce a high aspect ratio, in-plane, single-crystal-like lamellar structure. 相似文献
Molecular beams were used to grow amorphous and crystalline H(2)O films and to dose HCl upon their surface. The adsorption state of HCl on the ice films was probed with infrared spectroscopy. A Zundel continuum is clearly observed for exposures up to the saturation HCl coverage on ice upon which features centered near 2530, 2120, 1760, and 1220 cm(-1) are superimposed. The band centered near 2530 cm(-1) is observed only when the HCl adlayer is in direct contact with amorphous solid water or crystalline ice films at temperatures as low as 20 K. The spectral signature of solid HCl (amorphous or crystalline) was identified only after saturation of the adsorption sites in the first layer or when HCl was deposited onto a rare gas spacer layer between the HCl and ice film. These observations strongly support conclusions from recent electron spectroscopy work that reported ionic dissociation of the first layer HCl adsorbed onto the ice surface is spontaneous. 相似文献
Summary: Highly crystalline ferroelectric polymer films [vinyidene fluoride and trifluoroethylene, β‐P(VDF‐TrFE), 260–15 nm thick] were characterized with FTIR reflectance‐transmission microspectroscopy (FTIR‐RTM) mapping technique (400 µm × 400 µm spatial resolution). The amorphous and crystalline fractions were identified locally. FTIR‐RTM maps (1 cm2 area) provided a unique in‐depth view of the ultrathin films. Lower film thickness suppressed growth of the crystalline phase. Increased content of amorphous phase lead to non‐uniform films with degraded ferroelectric behavior.
FTIR‐RTM maps of the distribution of the amorphous phase in the 80 and 35 nm films. 相似文献
