Surface properties of poly(vinyl alcohol) films with a fluoroalkyl group at one end

Abstract

Surface properties of poly(vinyl alcohol) (PVA) films with a fluoroalkyl group at one end, H(CF 2)− n CH 2O(CH 2)− 3SPVA and F(CF 2)− 7CONHCH 2CH 2SPVA, were studied by contact angle measurements and X.p.s. analysis. H(CF 2)− n CH 2O(CH 2)− 3SPVA and F(CF 2)− 7CONHCH 2CH 2SPVA distributed preferentially on the air-side surface, and the surface showed properties corresponding to the characteristics of the fluoroalkyl end groups. Surface free energy, γ s, was in good agreement with critical surface tension, γ c, for F(CF 2)− 7CONHCH 2CH 2SPVA and n-C 12H 25SPVA, which had no polar component of γ s, and with γ c (max) for a series of H(CF 2)− n CH 2O(CH 2)− 3SPVAs which had a polar component. The γ s of F(CF 2)− 7CONHCH 2CH 2SPVA films altered by heat treatment, gave a minimum value at 80°C and increased with a rise in heat treatment temperature above 120°C, which was thought to be caused by distribution changes of the end groups. γ s was closely related to the distributions of CF 3 and CF 2 groups in the surface layer estimated by X.p.s. analysis.