CF4-plasma treatment

CF, - plasma (Figure S ). As expected, CF4 plasma treatment leads to dramatic effects surface fluorination is seen to be very efficient in regimes "A" and "B , but the fluorine concentration drops rapidly at elevated Vs. The presence of hydrophobic CFX groups maintains high 0a values, as expected r decreases only slowly with increasing substrate bombardment, presumably due to the resulting surface cross-linking. 

Pai, Y.-H. et al., CF4 plasma treatment for preparing gas diffusion layers in membrane electrode assemblies, J. Power Sources, 161, 275, 2006. 

Air plasma treatment was used to make one surface hydrophilic, and CF4 plasma treatment was used to make the other hydrophobic. Such a fabric with a different set of surface characteristics on each side can be made however, the success of this undertaking is contingent on which treatment is applied first. The sequence dependency of plasma treatments may be explained by the concept of plasma sensitivity of the elements involved in the two steps. Results are summarized in Tables 10.1 and 10.2. 

The CF4 plasma treatment yields F/C peak area ratio of approximately 1.5 for both cellulose and cellulose acetate films. When those surface-tagged films were immersed in liquid water, the fluorine atoms, which are detectable by XPS, decreases as a function of the immersion time. Figure 25.9 depicts change of F Is/C Is ratio as a function of immersion time in water, which shows that the disappearance rate of F Is peak is much higher for the semicrystalline cellulose film than that for the amorphous cellulose acetate film. These data actually compare the extent of X interaction rather than the degree of crystallinity, indicating that x interaction overwhelms the degree of crystallinity. 

Contact angles of water and of XPS FIs peaks for the subsequently treated samples showed the effect of the operational parameters of plasma polymerization coating of methane on the perturbability of the final surface with CF4 plasma treatment. The conditions of the plasma polymerization coating are manifested... 

The surface characteristics of nylon 6 treated with CH4 plasma are obviously different from those of untreated nylon 6. When the combined character of thickness and mobility (tightness of structure) of plasma polymer of methane reaches a certain level, it is anticipated that the CF4 plasma treatment of such a surface would have surface dynamic characteristics significantly different from that of nylon 6. Figure... 

Figure 29.5 Changes in ESCA signals of nylon 6 film on CF4 plasma treatment and subsequent water immersion (120 min).

The functionalization of CNTs through plasma treatment represents a novel and easy approach to scale up towards industrial applications. In more recent works, there were many attempts to fluorinate CNT sidewalls in such manner. The CF4 plasma treatment of SWNT sidewalls was demonstrated to enhance the reactivity of tubes with aliphatic amines.The cure reaction of diglycidyl ether of bisphenol A-based epoxy resin (DGEBA), when reacted with butylamine molecules (BAMs) anchored on to the plasma treated fluorinated SWNTs, was reported. The advantage of this method was that the functionalization could be achieved through a simple approach, which is widely used in thin film technologies. As covalently modified CNTs with fluorine groups offer the opportunity for chemical interactions with the amine systems, it was recently demonstrated that this... 

The CF4 plasma treatment led to a decrease in the permeability of both water and toluene. With the CO2 treatment, on the other hand, water permeability increased and toluene permeability decreased. Figure 4.24 shows the AFM image of the untreated PA12 surface for different scan sizes. Figures 4.25 and 4.26 show the AFM images of CF4 and CO2 plasma-treated PA12 membranes, respectively. Obviously, the surface changed after plasma treatments. A denser layer was formed by the plasma treatment. 

Compared to CF4 plasma treatment, CO2 plasma treatment led to a change in the morphology toward the less homogeneous, and the change covered practically the whole surface. In both cases, the alteration of the topography cannot be the result of deposition because CF4 and CO2 are known not to be polymerized by plasma [46, 47]. Rather, the alteration is a modification of the surface by substitution followed by cross-linking and degradation phenomena. 

The CF4 plasma treatment of the CTA and the CTA blend (Olde Riekerink et al. 2002) membranes led to hydrophobic surfaces (a water contact angle of about 100 ) due to extensive fluorination of the top layer. The highest F/C ratio is observed after 2 min of plasma action. The etching effect is much less pronounced than in the case of the CO2 plasma, and the CF4 plasma treatment also has much less impact on the permeation of the CTA membranes. Prolonged treatment was necessary to obtain a relatively small flux increase. CF4 plasma treatment caused an increase in the membrane s molecular weight cutoff. 

GDL s hydrophobic properties. Pai et al. [51] investigated MEA performance with a CF4 plasma-treated earbon eloth GDL. Polarization measurement showed that the CF4 plasma-treated module indeed enhanced cell performance, as compared to MEAs with a non-wet-proofed GDL, a 10 wt% PTFE dip-coated GDL, and a commercially available GDL. The CF4 plasma treatment does not leave excessive hydrophobic material residuals to block or seal the gas diffusion pores, flius flie surface-plasma-treated GDL shows a promising future with PEMFCs. 

Reactive Etching of Porous Alumina using CF4-Plasma Treatment... 

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