Plasma surface treatment of poly(acrylonitrile) films by fluorocarbon compounds

X-Ray Photoelectron Spectroscopy for Characterization of Engineered Elastomer Surfaces

“…From these data it is evident that for fluorination purposes CF4 is more effective than SF6. Previously, these results were explained in terms of the dissociation products formed in the plasma [32,66]. No significant differences in F/C ratio were found for the combination of inert carrier gases (Ar and He) and CF4, whereas He was more effective for fluorination in combination with SF6.…”

“…From systematic studies of fluorinating process under different conditions we concluded that high concentration of fluorine on the elastomer surface, typically higher than 7%, is associated with formation of fluorine-containing functional groups in form of CF, CF2 or CF3.The presence of CF and CF2 can be explained by H substitution and chain scissions [32], where -CF2-represents the main chain of the polymer, -CF-component could indicate crosslink sites [72], and-CF3 component indicates end groups of polymer chains [72] and grafting [32]. These findings imply enhancing of cross-linking in the elastomer due to plasma processing with fluorine-containing gas.…”

“…Though nowadays plasma processing is performed mostly at low pressures, atmospheric plasma systems provide an appealing alternative to vacuum plasma systems because continuous processing can be performed at a lower cost [62,[64][65][66]. Operation under atmospheric pressure provides high flexibility and portability to this technique [32] and allows it expansion to processing of a larger number of materials [62]. One of the possibilities of atmospheric plasma treatments is the use of a plasma torch [67].…”

“…The analysis of the HR C 1s (Figure 2 a, b) revealed the changes in the shape of the core level peak that evidenced not only significant increase in the C-O bonds after the fluorination treatments, but also the apparition of new functional groups involving carbon, oxygen and fluorine. The presence of CF and CF2 can be explained by H substitution and chain scissions [32]. CF2-represents the main chain of the polymer,-CF-component could indicate cross-link sites [72] and -CF3 component indicates end groups of polymer chains [72] and grafting [32].…”

“…From the shape of the peaks one can observe again that CF4 is more effective than SF6 in fluorinating because of the presence of additional fluorine containing groups together with the increase in the total fluorine content already mentioned in Table 6. SF6 molecules mainly dissociate into fluorine atoms and SF5 radicals [66], whereas CF4 produces fluorine, CF, CF2 and CF3 radicals that react with the elastomer surface leading to a substantial incorporation of fluorine [32]. Though fluorine atoms were considered as the main responsible of the fluorination process, CFx radicals could contribute to formation of highly fluorinated components (in particular CF3 groups) [65].…”