Thin layer polymerization

PPy-Pd In-situ chemical (vapor phase) polymerization Thin layer NHj [56]... 

Barraud A, Rosilio C and Ruaudel-Teixier A 1980 Polymerized monomolecular layers a new class of ultrathin resins for microlithography Thin Soiid Fiims 68 91-8... 

In the paste coating method, a PVC paste, which contains emulsion-polymerized PVC and additives, is appHed onto a substrate and heated to gelation before fusion to produce a coating layer. This method is employed for products with a thin layer, ie, of 0.007—0.05 mm thickness. For foamed vinyl-coated fabrics, a substrate is laminated onto a transfer paper on which a PVC paste containing a foam-blowing agent has been appHed and geUed. After removal of the transfer paper, the paste is blown. 

SSIMS has been used in the TOP SSIMS imaging mode to study very thin layers of organic materials [3.32-3.36], polymeric insulating materials [3.37], and carbon fiber and composite fracture surfaces [3.38]. In these studies a spatial resolution of ca. 80 nm in mass-resolved images was achieved. 

Polymerization in aqueous solution of acrylamide can also be fulfilled in thin layers (up to 20 mm) applied on a steel plate or a traveling steel band. Polymerization is initiated by persulfates, redox system, UV or y radiation. Polymerization proceeds in isothermal conditions as the heat of polymerization is dissipated in the environment and, additionally, absorbed by the steel carrier. Nonadhesion of the polymer to the carrier is ensured by the addition of glycerol to isopropyl alcohol or by precoating the steel band with a film based on fluor-containing polymers. This makes polymerization possible at a high concentration of the monomer (20-45%) and in a wider process temperature range. This film of polyacrylamide is removed from the band, crushed, dried, and packed. 

In the case of photoinitiated polymerization, an oxygen-free aqueous solution of acrylamide with a concentration of about 50% mixed with a photosensibilizer and other required additives is passed through a column-type apparatus with exterior water-cooling. A thin layer of the solution is exposed to a mercury lamp, acquires the consistency of a plastic film, which then can be passed through a second exposure zone, and is crushed and dried. Acrylamide polymers produced by this method are easily soluble and have a low residual monomer content. 

Very thin films may be also obtained through adsorption of a thin layer from solution [11,71,74] or chemical grafting [98] which is achieved by a polymerization reaction at the surface. A polymer film may also be deposited on the surface by plasma polymerization [99]. It is then, however, usually crosslinked and chemically not well-defined. 

We use extrusion coating to apply thin layers of polymer to the surface of non-polymeric substrates such as cardboard or aluminum foil. Extrusion coated materials are extensively used in food packaging. Products include the coated cardboard used to make milk cartons and the coated aluminum foil used to seal dairy product tubs. The process of extrusion coating has much in common with film casting. 

Calcium carbonate used as an additive in polymeric systems, is a hydrophilic, finely divided powder. When used as a component in polyolefins, the calcium carbonate s surface is modified by coating it with a thin layer of stearic acid. Why would compounders prefer to use the stearic acid coated material over the uncoated mineral ... 

Instead of using plasma-polymerized polyfluorocarbon as HIL, Qiu et al. utilized a thermally deposited Teflon (polytetrafluoroethylene) thin layer as a HIL, which results in... 

Dissolved oxygen (which tends to inhibit the reaction) is removed under a vacuum. Four volumes of ammonium persulphate (3.0 g l-1) are added and gently mixed before pouring into the mould. The mixture is covered with a thin-layer of water to exclude air and allowed to polymerize (approximately 30 min). Protective gloves should be worn and the preparation of the gel carried out in a fume cupboard because the monomers are toxic. 

CVD processes can also be used to grow polymers from nanocarbons. An important example is the coating of a CNT forest with a thin layer of poly(tetrafluorethlylene) (PTFE) via hot filament CVD to produce a superhydrophobic substrate [245]. Here, a vertically aligned MWCNT forest was prepared and placed in a CVD reaction chamber. Hexafluorpropylene oxide gas was then thermally decomposed to form the reactive radical difluorocarbene (CF2) and flowed over the CNT substrate along with a small amount of initiator where direct polymerization of PTFE onto the CNTs occurred [245]. 

No carboxylic acid functionality was detected either by thin-layer chromatographic analyses or by end-group titration. Therefore, procedures are now available to control the carbonation of polymeric organolithium compounds to efficiently produce either the carbox-ylated chain ends or the corresponding ketone dimer. 

In a related study by Contractor and coworkers [47] similar structures were produced but without the chemical polymerization step. The production of the structure used a polycarbonate membrane, where first a thin layer of Au was deposited over the top and bottom surfaces of the membrane (Figure 1.10a). Upon... 

The condensation polymerization process, employed recently by Skourlis et al. (1993) and Duvis et al. (1993), involves immersion of carbon fibers in a solution containing hexamethylenediamine and sodium carbonate. Dried carbon fibers are then immersed in a dipolychloride solution in carbon tetrachloride where the interfacial polycondensation reaction takes place. The result is that a thin layer of polyamide (nylon 6,6) coating is deposited on the continuous carbon fiber, whose thickness is controlled though by varying the diamine concentration. 

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