Acrylonitrile plasma-polymerized

There have been several studies of plasma-polymerized acrylonitrile (Hirai and Nakada, 1968 Munro and Grunwald, 1985 Bhuiyan et al., 1988 Bhuiyan and Bhoraskar, 1988 Tyczkowski and Sielski, 1990). Tyczkowski and Sielski have reported that both electrons and holes are mobile with comparable mobilities. The mobilities increase with increasing conductivity. For very high conductivities, a transition from hopping to extended-state transport was reported. 

Figure 11.2 Curling force o d, the product of the internal stress and thickness d of the plasma-deposited layer, versus d the three curves correspond to layers obtained by plasma polymerization of the following monomers O, pyridine A, acrylonitrile , thiophene , tetramethyldisiloxane.

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. 

There has been a great deal of interest in the study of the electrical properties of plasma polymerized films. Early data on the dielectric and conductivity of the films has been reviewed by Mearns ( ). More recently, the dielectric properties of plasma polymerized styrene (69-71), acrylonitrile (72), hexamethyldisiloxane (73-75), tetrafluoroethylene... 

A membrane designated "Solrox" made by Sumitomo Chemical Company is closely related to the above plasma polymerized composite membranes. A 1980 report by T. Sano described the Sumitomo process (31). A support film was cast from a polyacrylonitrile copolymer containing at least 40 mole percent acrylonitrile. The support film was dried and exposed to a helium or hydrogen plasma to form a tight cross-linked surface skin on the porous polyacrylonitrile support film. Data in a U.S. Patent issued in 1979 to Sano et al showed that the unmodified support film had a water flux of 87 gfd (145 L/ sq m/hr) at 142 psi (10 kg/sq cm). After the plasma treatment a reverse osmosis test using 0.55 percent NaCl at 710 psi (4895 kPa) showed 10.5 gfd (17.5 L/sq m/hr) flux at 98.3 percent salt rejection (32). This membrane appears to fall between a conventional asymmetric membrane and a composite membrane. If the surface skin is only cross-linked, one might call it a modified asymmetric membrane. However, if the surface skin is substantially modified chemically to make it distinct from the bulk of the membrane it could be considered as a composite type. 

The hydrophilic surface structures of plasma polymerized acrylonitrile are also investigated by both 13C and 15NNMR spectroscopies. In the samples of plasma polymerized acrylonitrile and a polymer produced near the electrode only amine signals were detected. However, the spectra of a film produced from acrylonitrile under nitrogen gas show a number of amide/amine signals in a wide chemical shift range (80 ppm). In addition, the polymer formed near the... 

Early work by Buck and Davar89 examined the plasma polymerization of several monomer systems. Best results in terms of reverse osmosis performance were achieved with vinylene carbonate/acrylonitrile and vinyl acetate/acrylo-nitrile. 

In a similar vein, hydroxyl and carboxylic acid functionalities can be incorporated by plasma-polymerizing acrylic acid [50] or ally alcohol [48]. Another technique commonly employed to incorporate specific atomic species is the use of co-reactants along with the primary monomer. In one such example, ammonia or acrylonitrile was used as the... 

Plasma polymerization was also applied to obtain an RO membrane, taking as a support a microflltration PP membrane or a UF PSU membrane. All used monomers (AAc, acrylonitrile, allylamine, ethylenediamine, n-propylamine, and methyl methacrylate) in proper plasma conditions improved the RO performance and the membrane resistance of chlorine (Kim and Kim 2001,2006). 

On the other hand, coating techniques do have less influence on the fibre surface. Nevertheless, brittle coatings such as SiC deteriorate mechanical properties of the fibres. As an example, reactive sputtered SiC layers improve the interfacial shear strength of carbon fibre reinforced epoxy resin /3/. Recently, Dagli and Sung 141 reported about the coating of carbon fibres by plasma polymerization of acrylonitrile and styrene using an inductively coupled plasma. 

Frequently plasma polymers are not classified in respect of the type of monomer but from a point of view of their chemical composition and morphology. For example, amorphous (a-) covalent material obtained by plasma polymerization of silane (SiFLj), which is composed of silicon and hydrogen, can be termed as a-Si H. In turn, amorphous plasma polymer deposited from acrylonitrile (C3H3N) can be called as plasma-polymerized (pp-) acrylonitrile or a-CxNy H. It is usually met, but it is not a rule, that if the plasma polymer structure is close to a covalent glass structure, the latter notation is used. If plasma polymer reveals nano- or microcrystalline structures, prefixes nc- or pc- are put in the place of a-. 

Why is the polymerization so selective toward the monomer si cies Alkyl esters of methacrylic acid are polymerized by plasma exposure, but styrene (St), a-methylstyrene (a-MeSt), acrylonitrile (AN), iV-vinylpyrrolidone (VPdn), the sodium salt of /7-styrene-sulfonate (NaSS), and other vinyl monomers are not susceptible to the polymerization. 

Alternately, energetic particle radiation-assisted methods (e.g., plasma, gamma irradiation, and electron beam irradiation) enabled a rapid formation of active sites to initialize the all-solid-state polymerization process and avoid the introduction of chemical impurities. A PE membrane had been coated with acrylonitrile (AN) (Kim et al., 2009) via a plasma technology. The ion conductivity was improved from 0.4 to 1.4 mS/cm, and the average peeling force was increased to 22.6 N/m or by up to 18%. The resulting LIB also exhibited rather a stable cycle performance. 

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