Ar-plasma treatment

To enhance the formation of Ti species by reduction and nitration together, treatment with H2+N2 plasma and H2+Ar/N2+Ar (H2+Ar treatment followed by N2+Ar) were tried. However, there was no further improvement. H2+Ar/N2+Ar plasma treatment reduced the optimum treatment time to 20 minutes but improvement of photocatalytic activity imder fluorescent light was just 2.0 times. H2+Ar pretreatment seems to make substitutional doping of N easier through reduction reaction. 

O2 plasma treatment was also effective for the improvement of photocatalytic activity. Although the improvement was not as high as H2+Ar or N2+Ar plasma treatments, O2 plasma treated films show photocatalytic activities up to 1.3 times higher under UV-A and up to 1.7 times higher under fluorescent light than an untreated film. According to ESCA analysis, the improvements seem to attribute to the cleaning effect of O2 plasma. 

Figure 2. Spectrum of PTFE after 2 min Ar plasma treatment. SIMS as in Fig.l. For plasma conditions, see text.

Figure 10.14 The decay of fluorine contamination with continued reactor use, involving multiple intermittent chamber evacuations and O2 and Ar plasma-treatments of new substrates other than this intermittent use and times when chamber-cleaning procedures were employed, the reactor is continually under vacuum, indicating that this contamination does gradually pump out.

It should be pointed out that excellent primer adhesion was also obtained with TMS plasma polymers from a (TMS-bAr) mixture in a closed reactor system. This result indicated that, to achieve equally good primer adhesion, TMS polymerization with subsequent Ar plasma treatment could be replaced by one process of cathodic polymerization of a (TMS-bAr) mixture. Since the addition of argon to TMS can help stabilize the gas discharge, plasma polymerization of a (TMS + Ar) mixture is very important in the practical operation of plasma deposition process in conjunction with the industrial IVD process. Plasma polymerization of a mixture of TMS and argon in a closed system also has the advantage of being more... 

Figure 32.21 summarizes results of Rp measurement of TMS plasma-coated Alclad 7075-T6 panels under IVD conditions in both closed and flow reactor systems, with and without subsequent Ar plasma treatments. TMS plasma coatings produced in a closed reactor system showed higher Rp values than those obtained in a flow reactor system. The second Ar discharge treatment of the flow system TMS coating remarkably increased the Rp value to nearly comparable to that for the closed system TMS. The second Ar plasma treatment of the closed system TMS coating, on the other hand, reduced the value of Rp slightly from that for the closed system TMS. 

Figure 34.4 Effect of Ar plasma treatment a silicone membrane on the gas flux and the O2/N2 selectivity.

A significant inCTease in the polarity of the PDMS nanofiltration membranes after Ar plasma treatment (also in the admixture with H2 or O2) was observed (Aerts et al. 2006). This lowered the retention of two charge-bearing dyes, while the retention for a neutral component increased. The solvent permeability was also affected. The decreased permeability was attributed to the cross-linking and the hydrophilization of the membrane surface. 

Zanini S et al (2005) Modifications of lignocellulosic fibers by Ar plasma treatments in comparison with biological treatments. Surf Coat Technol 200(1 ) 556-560... 

Fig. 13. Contact angle of Tecoflex after 30 s SO2 and Ar plasma treatment as a function of time and environment...

Fig. 24.5 Schematic representation of polyacrylic add (PAAc) graft modification by Ar plasma treatment (Reprinted with permission from Tyszler et til. 2(X)6, Copyright 2006 Elsevier)...

Other investigations on argon plasma treated PE, but not in situ, show very different results. Therefore, in [112] it is shown that argon RF plasma treatment of PE determines both an increase of surface energy ys and (O -I- N)/C ratio, with almost the same increasing rates (Fig. 15, curves 1, 2). This fact seems to indicate that Ar plasma treatment introduces polar groups just in a very thin layer, similar to that the contact angle measurement can probe [112]. 

Several studies of the preparation of gas separation membranes by low pressure plasma treatment have been reported. Kawakami et al. demonstrated that the selectivity of O2 over N2 increased somewhat by plasma treatment of natural rubber (7). Yasuda et al. have found that CO2 selectivity over CH4 of poly(dimethylsiloxane) increased by about 20-fold after Ar plasma treatment 4), Matsuyama et al. investigated in detail the OO2 permeability and selectivity over CH4 of poly(dimethylsiloxane) membranes modified by plasma treatment using Ar, N2, O2 and NH3 and demonstrated that the selectivity of CO2 over CH4 was remarlrably improved by plasma treatment. They also observed that the selectivity showed a maximum with treatment time (i). 

Figure 13.12 (a) FESEM images of as-spun polystyrene nanofibers with a large-scale image in the inset, (b) Ag nanotube of 42 nm ion beam sputtered after the dissolution of polystyrene in a CH2CI2 solution, (c) porous Ag nanotubes after an Ar plasma treatment of... 

Gancarz et al. [90] compared the three different approaches to modify PS membranes with AA through plasma-initiated graft polymerization (1) grafting in solution, the plasma-treated polymer membrane was exposed to air for 5 min and dipped into a deaerated aqueous solution of monomer (2) grafting in vapor phase, when Ar plasma treatment on polymers was completed, a monomer vapor was introduced into the chamber and (3) plasma polymerization of monomer vapors in a plasma reactor. It was shown that modified PS membranes prepared in a vapor phase possessed the highest flux. 

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