Synthesis, characterization, and properties of a novel acrylic terpolymer with pendant perfluoropolyether segments

Abstract

A novel acrylic terpolymer with pendant perfluoropolyether (PFPE) segments has been synthesized and fully characterized. By hexamethylene diisocyanate functional groups PFPE monofunctional macromonomers have been grafted on a poly(butyl methacrylate-co-hydroxyethyl acrylate-co-ethyl acrylate) random terpolymer. Such grafted copolymer behaves like an interface-active material, since the perfluoropolyether segments in solvent cast films rearrange themselves at the air–polymer interface by surface segregation. In addition, blends of the above graft copolymer with acrylic base polymers (either the terpolymer itself or a commercial copolymer) have been examined in terms of surface segregation and fluorine enrichment of the external layers.The critical surface tension, γc, of solid films made of the neat graft copolymer as well as of the polymer blend has been evaluated by contact angle measurements and Zisman plots. Even a small addition (5wt%) of the fluorinated copolymer to the acrylic component has been found very effective in lowering the surface tension. The outermost surface composition has been investigated by XPS technique, confirming the strong fluorine enrichment. Furthermore, SEM and EDX analyses have been performed on cross-sectioned films, showing that in the above polymer blends macrophase surface segregation has originated a thick layer made of fluorinated copolymer close to the air–polymer interface.