The wetting properties of a series of polyacrylates containing the fluoroalkyl group \documentclass{article}\pagestyle{empty}\begin{document}$ [\rlap{--} ({\rm CF}_{\rm 2} \rlap{--} )_2 {\rm CF}_2 {\rm H}\ $\end{document} have been studied. Where n is 7 and 9, the polyacrylates are highly crystalline at room temperature. Since the polymers were prepared under atactic free‐radical conditions and the polyacrylates with shorter alkyl groups (where n is 3 or 5) were not crystalline at room temperature, the crystallinity is presumed to occur as a result of side‐chain packing and not involve the backbone. The polymers become more wet‐table (higher γc) as polymer crystallinity was reduced by quenching or heating past Tm. Correlations have been made between the work of Zisman and co‐workers on the wetting properties of various fluorinated acid monolayers and the wetting properties of these fluoroalkyl acrylates. The results obtained in this study concerning the influence of polymer crystallinity on surface wetting are discussed in relation to the findings of Schonhorn and Ryan on the wettability of polyethylene single crystal aggregates.

synopsisThe critical surface tension of wetting ( ye) for certain branched-chain polymeric fluoroalkyl acrylates and methacrylates was obtained. Polymeric materials utilized in this study can be represented by the repeating units +CH*-C(R)(COOCR'( CFXX*, where R is H or C H , R' is H or F, and X is F or C1, by +CH,-CH(COO(CH&OCF-(CFa)2)+, where n is 2,5, or 11, and by +CH-C(R)(COOCH*(CFt)n'CFa*, where R is H or CHa and n' is 2 or 6. Monomer synthesis involved either the direct acylation of a fluoroketone-metal fluoride adduct or a fluoroalcohol with acryloyl or methacryloyl chloride or a displacement reaction between a fluoroketone-metal fluoride adduct and an w-bromoester. In generd, modifications in the pendent fluoroalkyl group affected ye in a manner predictable from previous work by Zisman et al.; e.g., yc was inoreased when either H or C1 was substituted for F in the side chain. In polymeric alkyl acrylates containing a heptafluoroisopropyl side chain yc increased as the fluorocarbon group was removed from the proximity of the polymer backbone by intervening methylene groups. A comparison of the wetting properties of polyacrylatm containing either a perfluoroisopropyl or n-perfluoropropyl group showed that the polymer containing the isopropyl group had a lower yc.

SynopsisA systematic surface fluorination of high-density polyethylene was carried out using CF4, CFBH, CF3C1, and CF3Br, in a radio-frequency glow discharge. Based on ESCA and wettability measurements, all of these compounds provided a fluorocarbon layer on high-density polyethylene surface, but the fluorine to carbon ratio and extractability of the films were strongly dependent on the starting materials and the location of the sample specimen in the reactor chamber as well as the duration of the reaction. The results with vertically held, CF3H-treated samples showed a high level of nonextractable surface fluorination and very little change in wetting properties before and after extraction with CF2ClCFC12.