Plasma-polymerized polymer

The results from Miyachi et al. [64] showed that nonspecific adsorption of target DNA is decreased when SA embedded in a plasma-polymerized polymer thin film glass substrate is used (Fig. 3). The embedded SA on this substrate can selectively attach to biotinylated-probe ssDNA, which showed selective hybridization to complementary target DNA and a higher signal-to-noise ratio due to the low nonspecific DNA binding on substrate. However, we have to use a special polymerized system to fabricate thin polymer film by this method. 

Figure 9-19. Schematic of an RF plasma system for plasma polymerization (polymer film deposition) (1) RF generator, (2) plasma zone (3) heated window (4) engine (5) rotating substrates (6) flexible connection (7) air valve (8) vacuum valve (9) manometer, (10) cooled trap (11) vacuum pump (12) quartz gauge for measurements of the film thickness (13) photodiode (14) registration system (15) polymer deposition chamber (16) laser (17) argon tank (18) valve (19) dose valve (20) tank with a manometer, (21) manometer.

Conventional Tests of adhesion are not well suited to measurement of thin dims. The scratch test has been used to characterize the adhesion of thin hlms, such as plasma-polymerized polymers or evaporated metals, on hard substrates. 

The deposition of organic films by plasma polymerization is an important application of non-thennal plasmas 1301. Plasma polymers are fonned at the electrodes and the walls of electrical discharges containing organic vapours. Oily products, soft soluble films as well as hard brittle deposits and powders are fonned. The properties of plasma... 

Photopolymerization and Plasma Polymerization. The use of ultraviolet light alone (14) as well as the use of electrically excited plasmas or glow discharges to generate monomers capable of undergoing VDP have been explored. The products of these two processes, called plasma polymers, continue to receive considerable scientific attention. Interest in these approaches is enhanced by the fact that the feedstock material from which the monomer capable of VDP is generated is often inexpensive and readily available. In spite of these widespread scientific efforts, however, commercial use of the technologies is quite limited. 

Solution polymerization of VDE in fluorinated and fluorochlorinated hydrocarbons such as CEC-113 and initiated with organic peroxides (99), especially bis(perfluoropropionyl) peroxide (100), has been claimed. Radiation-induced polymerization of VDE has also been investigated (101,102). Alkylboron compounds activated by oxygen initiate VDE polymerization in water or organic solvents (103,104). Microwave-stimulated, low pressure plasma polymerization of VDE gives polymer film that is <10 pm thick (105). Highly regular PVDE polymer with minimized defect stmcture was synthesized and claimed (106). Perdeuterated PVDE has also been prepared and described (107). 

The Auger depth profile obtained from a plasma polymerized acetylene film that was reacted with the same model rubber compound referred to earlier for 65 min is shown in Fig. 39 [45]. The sulfur profile is especially interesting, demonstrating a peak very near the surface, another peak just below the surface, and a third peak near the interface between the primer film and the substrate. Interestingly, the peak at the surface seems to be related to a peak in the zinc concentration while the peak just below the surface seems to be related to a peak in the cobalt concentration. These observations probably indicate the formation of zinc and cobalt complexes that are responsible for the insertion of polysulfidic pendant groups into the model rubber compound and the plasma polymer. Since zinc is located on the surface while cobalt is somewhat below the surface, it is likely that the cobalt complexes were formed first and zinc complexes were mostly formed in the later stages of the reaction, after the cobalt had been consumed. 

The dendritic growth of lithium was suppressed on a lithium electrode surface modified by an ultrathin solid polymer electrolyte prepared from 1,1—difluoro-ethane by plasma polymerization [114]. 

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. 

Chemical alternation of the surface layer and deposition of a new layer on top of the silicone mbber can be achieved by physical techniques. For the inert surface of silicone rubber, the former requires the generation of high-energy species, such as radicals, ions, or molecules in excited electronic states. In the latter case, coatings of atoms or atomic clusters are deposited on polymer surfaces using technique such as plasma (sputtering and plasma polymerization) or energy-induced sublimation, like thermal or electron beam-induced evaporation. 

Srikanfh, H., Hajndl, R., Chirinos, C. and Sanders, J. (2001) Magnetic studies of polymer-coated Fe nanopartides synthesized by microwave plasma polymerization. Applied Physics Letters, 79, 3503-3505. 

In a previous section, the effect of plasma on PVA surface for pervaporation processes was also mentioned. In fact, plasma treatment is a surface-modification method to control the hydrophilicity-hydrophobicity balance of polymer materials in order to optimize their properties in various domains, such as adhesion, biocompatibility and membrane-separation techniques. Non-porous PVA membranes were prepared by the cast-evaporating method and covered with an allyl alcohol or acrylic acid plasma-polymerized layer the effect of plasma treatment on the increase of PVA membrane surface hydrophobicity was checked [37].The allyl alcohol plasma layer was weakly crosslinked, in contrast to the acrylic acid layer. The best results for the dehydration of ethanol were obtained using allyl alcohol treatment. The selectivity of treated membrane (H20 wt% in the pervaporate in the range 83-92 and a water selectivity, aH2o, of 250 at 25 °C) is higher than that of the non-treated one (aH2o = 19) as well as that of the acrylic acid treated membrane (aH2o = 22). 

Infrared Spectrum. The plasma polymerized organic film shows features distinctive from the conventional polymer. According to ESR measurements (31), the film contains a high concentration of residual free radicals, which showed a relatively long life time. The free radicals were oxidized in air and the oxidization is promoted significantly at elevated temperatures. The film is not soluble in usual solvents and it is more thermally stable than the conventional polymers. These properties are thought to be caused by the highly crosslinked structure of the film (32). 

Dielectric Loss. Usually, the dielectric loss of plasma polymerized hydrocarbon is larger than that of the conventional polymer by more than one order of magnitude. This difference is supposed to be caused by the oxidation of the film (J34). For both samples of PPE, a loss peak appeared at -30 °C at the measurement frequency of 1 KHz. The activation energy of this peak was 0.68 eV as shown in Fig. 8 for both samples. This value was almost same as... 

A. Taniguchi and K. Yasuda. Waterproofing of carbon paper by plasma polymerization. Journal of Applied Polymer Science 100 (2006) 1748-1753. 

Surface treatments of carbon fibers can in general be classified into oxidative and non-oxidative treatments. Oxidative treatments are further divided into dry oxidation in the presence of gases, plasma etching and wet oxidation the last of which is carried out chemically or electrolytically. Deposition of more active forms of carbon, such as the highly effective whiskerization, plasma polymerization and grafting of polymers are among the non-oxidative treatments of carbon fiber surfaces. 

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