Polymeric thin films

Various photochromic systems employing polymeric thin films or LB... 

Organic polymeric flocculating agents, mechanisms of, 77 632-633 Organic polymeric thin films, quasi phase matching in, 7 7 451 Organic polymers... 

Film thickness can govern the morphology, stability, and surface-chemical expression of polymeric thin films. NIST researchers developed a process for producing gradients, termed flow coating, which is a modified blade-casting technique [3-5]. How coater instrumentation and the flow coating process are illustrated in Fig. 2. To create the library, a dilute solution of polymer in solvent (1-5% mass fraction) is injected into the gap between a doctor blade positioned over a flat substrate... 

Stafford CM, Harrison C, Beers KL, Karim A, Amis EJ, Vanlandingham MR, Kim HC, Volksen W, MrUer RD, Simonyi EE (2004) A budding-based metrology for measuring the elastic moduli of polymeric thin films. Nat Mater 3 545-550... 

A very common and useful approach to studying the plasma polymerization process is the careful characterization of the polymer films produced. A specific property of the films is then measured as a function of one or more of the plasma parameters and mechanistic explanations are then derived from such a study. Some of the properties of plasma-polymerized thin films which have been measured include electrical conductivity, tunneling phenomena and photoconductivity, capacitance, optical constants, structure (IR absorption and ESCA), surface tension, free radical density (ESR), surface topography and reverse osmosis characteristics. So far relatively few of these measurements were made with the objective of determining mechanisms of plasma polymerization. The motivation in most instances was a specific application of the thin films. Considerable emphasis on correlations between mass spectroscopy in polymerizing plasmas and ESCA on polymer films with plasma polymerization mechanisms will be given later in this chapter based on recent work done in this laboratory. 

Some of the modern surface analysis methods have been used to study the surface chemistry of both plasma etched surfaces and plasma polymerized thin films. Much of this work has involved exposure of these surfaces to air as the samples are transferred from the plasma system to the surface analysis system. However, in a few cases surface analysis has been performed in the plasma system after the plasma gas has been pumped away. This work will be discussed in more detail later in this chapter. 

Kirby, B.J., Wheeler, A.R., Shepodd, T.J., Fruetel, J.A., Hasselbrink, E.F., Zare, R.N., A laser-polymerized thin film silica surface modification for suppression of cell adhesion and electroosmotic flow in microchannels. Micro Total Analysis Systems, Proceedings 5th pTAS Symposium, Monterey, CA, Oct. 21-25, 2001, 605-606. 

Chapman RG, Ostuni E, Liang ME et al (2001) Polymeric thin films that resist the adsorption of proteins and the adhesion of bacteria. Urngmuir 17 1225-1233... 

K. E. and Street, R.A. (2002) Organic polymeric thin-film transistors fabricated by... 

These plasma polymerized thin films have become increasing popular in the last few years, particularly, teflon like polymers, owing to their exceptional properties some of which are described below. 

Sekkat, Z., Morichere, D., Dumont, M., Loucif-Saibi, R., and Del, J. A. (1992K Photoisomerization of azobenzene derivatives in polymeric thin films, f. Appl. Phys. 11, 1543-1548. 

Copolymers. The copolsmers were prepared by emulsion polymerization in a "pop bottle" polymerizer at 80° C using sodium aryl alkyl sulphonate (Ultrawet K) as emulsifier and ammonium persulphate as catalyst. The polymerizations were carried to greater than 95% conversion (4-8 hr) and the feed concentrations of the vinyl ketones were taken as their concentrations in the polymer. Copolymers containing 1% and 5% by weight of vinyl ketones were prepared. The cqsolymers were not homogeneous in ketone concentration since the reactivity ratios indicated that the vinyl ketones would be used ip before the end of the polymerizations. Thin films were prepared for irradiation by compression molding in a Carver Press at 150° C at 20,000 psi. The films were usually 0.22 mm thick. 

Polymerized thin films have been formed by several methods such as glow discharge, photolysis, electron bombardment and vacuum evaporation. The films formed in a glow discharge are pinhole free and possess a number of unique and desirable properties. The glow discharge methods are also simpler than the other methods from a processing point of view. 

Dalton, L.R., Harper, A.W., Robinson, B.H. The role of London forces in defining noncentrosym-metric order of high dipole moment-high hyperpolarizability chromophores in electrically poled polymeric thin films, Proc. Nat. Acad. Sci. USA 94, 4842-4847 (1997)... 

Thin films of the photoreactive liquid crystals containing 0.5 wt % of initiator (10-biphenyl-4-yl-2-isopropyl-9-oxo-9H-thioxanthen- 10-ium hexafluor-phosphate) were polymerized in the smectic phases by irradiation of blue semiconductor laser (X = 405 nm). Polymerization of the oxetane moiety proceeded via cationic intermediates. The carrier transport characteristics of the polymerized thin films were studied by the time-of-flight technique. 

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