Substrate polymer preparation

Another recently discovered form of epitaxy is graphoepitaxy (Geis et al. 1979). Here a non-crystalline substrate (often the heat-resistant polymer polyi-mide, with or without a very thin metallic coating) is scored with grooves or pyramidal depressions the crystalline film deposited on such a substrate can have a sharp texture induced by the geometrical patterns. More recently, this has been tried out as an inexpensive way (because there is no need for a monocrystalline substrate) of preparing oriented ZnS films for electroluminescent devices (Kanata et al. 1988). 

The polymers and copolymers discussed here were all prepared by reaction of the homogeneous (linear) or heterogeneous (cross-linked) poly(vinylbenzylchloride) substrate polymer with the potassium or cesium salts of the suitably monofunctionalized donors (Reaction 1). 

When a polymer film is used as a substrate, aqueous Ti02 paste without organic surfactants is sintered at relatively low temperatures, with approximately 150°C being sufficient to produce mechanically stable 2 films. Sommeling et al. at ECN used an ITO-coated polyethylene terephthalate) (PET) film as a substrate and prepared a plastic DSSC [164-167]. A cell performance with a 7 of 15 pA/cm2, Voc of 0.48 V, and ff of 0.67 was obtained at an illumination intensity of 250 lux. This performance is sufficient for a power supply for indoor applications such as watches and calculators. Under AM 1.5 irradiation, a Vtx of 0.7 V and /sc of 2 mA/cm2 were obtained. 

Concentrated emulsions were also used to prepare substrates for the immobilization of enzymes and cells. Lipase was immobilized in hydrophobic porous polymers and the system employed in the hydrolysis of triacylglycerides [71]. Cells of Phanerochaete Chrysosporium were immobilized on porous poly(styrene-divinylbenzene) carrier and used for the degrading of 2-chloro-phenol [72]. The substrates were prepared as in Ref. 73. 

Solubility was enhanced by the presence of meta and ortho isomer links in the diamine portion of the molecule. Ttie polymers prepared with 3,3 -ODA and 2,4 -ODA were found to be readily soluble at 30-40% solids at room temperature in amide solvents. These polyimides are also readily soluble in low-boiling chlorinated solvents. They can therefore be spray-coated onto desired substrates in the fully-imidized form and thus eliminate the need for taking the substrate to elevated temperatures. Hiese soluble phenoxy-linked polyimides yield tough, flexible, colorless to pale yellow transparent films from amide or cholorinated solvents. Their potential for use in electronic applications should be excellent. 

The internal stress of plasma polymers is dependent not only on the chemical nature of monomer but also on the conditions of plasma polymerization. In the plasma polymerizations of acetylene and acrylonitrile, apparent correlations are found between and the rate at which the plasma polymer is deposited on the substrate [2], as depicted in Figure 11.3. The effect of copolymerization of N2 and water with acetylene on the internal stress is shown in Figures 11.4 and 11.5. The copolymerization with a non-polymer-forming gas decreases the deposition rate. These figures merely indicate that the internal stress in plasma polymers prepared by radio frequency discharge varies with many factors. The apparent correlation to the parameter plotted could be misleading because these parameters do not necessarily represent the key operational parameter. 

Matsui J, NichoUs lA, Karube 1, Mosbach K (1996) Carbon-carbon bond formation using substrate selective catalytic polymers prepared by molecular imprinting An artificial class II aldolase. J Org Chem 61 5414... 

In a typical experiment, 20 mg of thermal polymer in 20 ml of autoclaved 0.2 N tris buffer, pH 8.3, was incubated at 37.5° with 2.0 pCi of sodium l-i C-p3Tuvate (specific activity, 5/iCi//xmole, giving a substrate/polymer ratio of 0.02 /.imoles/mg). Incubation was usually for 24 hours, but occasionally for 48 or 72 hours, after which the liberated COa was assayed as barium carbonate. Similar results were obtained when radioactive acetate was counted. Aseptic precautions were taken during the preparation and assay of the polymers. Activities (cpm per 20 mg polymer per 24 hours. Table IX) were 30,000-33,000 for acidic 2 2 1-proteinoids, 33,000-41,000 for 1 1 1-proteinoids, and 33,000 for 1 1 3-proteinoid. A lysine-rich proteinoid gave a value of 15,800. Hydrolysates of polymers and unpolymerized mixtures of amino acids had activities of 4000-5000, only slightly greater than that of the spontaneous control (1000-3000). Enzymes other than carboxylase and other proteins gave values of 2000-5000. 

Matheson Gas Products) was used as the carrier gas. Substrates were prepared by vapor deposition of an opaque layer of aluminum on glass microscope slides. Polymer film thicknesses were determined by measuring the step height between a masked and unmasked portion of the specimen with a Rank, Taylor, and Hobson Talystep 1 traversing stylus. Deposited films were stored in a vacuum dessicator prior to measurement of the infrared spectra in order to minimize the absorption of moisture from the atmosphere. 

A capacitively coupled reactor designed to permit continuous coating of a moving substrate with plasma polymer has been described [ 1 ]. In this paper the results of a study of the plasma polymerization of tetrafluoroethylene in such a reactor presented. Plasma polymer has been deposited on aluminum electrodes as well as on an aluminum foil substrate placed midway between electrodes. The study particularly explores conditions in which deposition is minimized on the electrode. For this reason the chemical nature of the polymer formed in a low flow rate (F = 2 cm (S.T.P.)/min) and low pressure (p = 60 mlllltorr) plasma has been analyzed by the use of ESCA (electron spectroscopy for chemical analysis) and deposition rate determinations. This method combined with the unusual characteristics of TFE plasma polymerization (described below) has yielded Information concerning the distribution of power in the inter-electrode gap. The effects of frequency (13.56 MHz, 10 KHz and 60 Hz), power and magnetic field have been elucidated. The properties of the TFE plasma polymer prepared in this apparatus are compared to those of the plasma polymer deposited in an inductively coupled apparatus [2,3]. 

In the vacuum line method, membrane samples were prepared for exposure to acetylene in the dry box and then placed in a Schlenk tube. The tube was connected to a vacuum line for exposure to purified acetylene. The only real experimental difficulty encountered was too fast a rate of polymerization in the first experiment, the heat of polymerization actually melted the substrate polymer polypropylene. This problem was overcome by diluting the catalyst system prior to treating the substrate, thus leaving a smaller amount of catalyst on the pore walls. Slower polymerization rates resulted. Smaller quantities of acetylene were introduced in a stepwise manner (only 15 ml at a time) with time between steps to allow for heat dissipation. Once polymerization was complete, the sample was doped in the dry box. 

The grafting of an alternating copolymer on a substrate polymer occurs when the alternating copolymer is prepared under conditions normally used without the substrate polymer. When comonomers that are subject to spontaneous or thermal initiation are polymerized in the presence of a suitable polymer, graft copolymers are formed despite the absence of a radical catalyst (10). 

The use of a radical catalyst increases polymerization rate and the extent of grafting. When the reaction is done in an aqueous medium, as when the substrate polymer is charged as a latex, a water-soluble catalyst is necessary, as previously observed for the preparation of alternating copolymers in an aqueous medium (15). Although the latex... 

Prior to the mid-1950s, all thermoplastic acrylics were classic solution polymers prepared in suitable organic solvents. They were employed in a variety of applications, including general industrial finishes and appliance enamels and coatings for a variety of wooden, metallic, and plastic substrates. 

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