Polymeric films characterization

ETEROAROMATics FURAN AND THIOPHENE. The chemical transformation of thiophene at high pressure has not been studied in detail. However, an infrared [441,445] study has placed the onset of the reaction at 16 GPa when the sample becomes yellow-orange and the C—H stretching modes involving sp carbon atoms are observed. This reaction threshold is lower than in benzene, as expected for the lower stability of thiophene. The infrared spectrum of the recovered sample differs from that of polythiophene, and the spectral characteristics indicate that it is probably amorphous. Also, the thiophene reaction is extremely sensitive to photochemical effects as reported by Shimizu and Matsunami [446]. Thiophene was observed to transform into a dark red material above 8 GPa when irradiated with 50 mW of the 514.5-nm Ar+ laser line. The reaction was not observed without irradiation. This material was hypothesized to be polythiophene because the same coloration is reported for polymeric films prepared by electrochemical methods, but no further characterization was carried out. 

Mowery KA, Schoenfisch MH, Saavedra JE, Keefer LK, Meyerhoff ME. Preparation and characterization of hydrophobic polymeric films that are thromboresistant via nitric oxide release. Biomaterials 2000, 21, 9-21. 

Preparation and Characterization of Active Glucose Oxidase Immobilized to a Plasma-Polymerized Film... 

This study on the immobilization of glucose oxidase and the characterization of its activity has demonstrated that a bioactive interface material may be prepared from derivatized plasma polymerized films. UV/Visible spectrophotometric analysis indicated that washed GOx-PPNVP/PEUU (2.4 cm2) had activity approximately equivalent to that of 13.4 nM GOx in 50 mM sodium acetate with a specific activity of 32.0 U/mg at pH 5.1 and room temperature. A sandwich-type thin-layer electrochemical cell was also used to qualitatively demonstrate the activity of 13.4 nM glucose oxidase under the same conditions. A quantitatively low specific activity value of 4.34 U/mg was obtained for the same enzyme solution by monitoring the hydrogen peroxide oxidation current using cyclic voltammetry. Incorporation of GOx-PPNVP/PEUU into the thin-layer allowed for the detection of immobilized enzyme activity in 0.2 M sodium phosphate (pH 5.2) at room temperature. 

Wang, C.L., Kobayashi, Y., Togashi, H., Kato, K., Hirotsu, T., Hirata, K., Suzuki, R., Ohdaira, T., Mikado, T. (1999) Plasma-polymerized hexam-thyldisiloxane films characterized by variable-energy positron lifetime spectroscopy . J. Appl. Poly. Sci. 74(10), 2522. 

Acoustic wave (AW) devices are ideally suited to thin film characterization due to their extreme sensitivity to thin film properties [10]. The sensitivity of AW devices to a variety of film properties (see Chapter 3), such as mass density, viscoelasticity and conductivity, makes them versatile characterization tools. The ability to rapidly monitor changes in device responses resulting from changes in thin film properties permits their use for monitoring dynamic processes such as film deposition, chemical modification (e.g., photo-polymerization, corrosion), and diffusion of species into and out of films. 

Because powder formation can be characterized as the rapid formation of polymeric species in a localized gas phase, the quantity of particles or powders mixed in a coherent film that forms at a substrate surface should also be related to the rate of film formation. Thompson and Smolinsky [8] found a direct correlation between the particle density on the surface of a plasma-polymerized film and the growth rate of the film as depicted in Figure 8.14. 

Knoesen, A., Molau, N. E., Yankelevich, D. R., Mortazavi, M. A., and Dienes, A. Corona-poled nonlinear polymeric films In situ electric field meaairement, characterization and ultrashort-pulse applications. International Journal of Nonlinear Optical Physics, vol. 1, no. 1, 1992, p. 73-102. 

Solid Films. A solid polymeric film was observed to form in the discharge region when either methane or methyl chloride was passed through the discharge. Both films were characterized in several ways. 

Preparation of samples for the observation under TEM is more tedious and exacting than that used for SEM. The specimens have to be hardened and stained with Br, OsO, or RuO, microtomed into ca. 20 slices, mounted on a grid and polymeric film support and measured. Frequently, the SEM and TEM methods are being used in parallel. In all cases microscopy is considered but one method of characterization of polymer blends [Karger-Kocsis and JGss, 1987 Kyotani and Kanetsuna, 1987 Hsu andGeil, 1987]. 

We are pleased to present, in this volume, 26 reviewed and revised chapters from the symposium in six parts mechanisms of polymer wear controls of polymer wear tribological behaviors of polymers wear of biomaterials and polymer composites characterization and measurements of polymer wear and degradation and wear of polymeric films and filaments. 

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