Low surface energy polymeric films from novel fluorinated blocked isocyanates

Polymeric films with surface energies as low as 10 mN/m were prepd. from a mixt. of a hydroxyl-end-capped solventless liq. oligoester (SLO), a blocked polyisocyanate, and a novel fluorinated blocked isocyanate (FB-NCO). In the well-defined FB-NCO the ratio of the fluorinated tail and the caprolactam blocking group was 1:1. Low amts. of fluorine were needed for obtaining very low surface energies via the surface segregation of fluorinated species. The low wettability of films was manifested by high contact angles of water (125 Deg) and hexadecane (80 Deg), by adding less than 5 wt % of fluorine. The pronounced enrichment of fluorinated species at the surface was verified by XPS. The curing temp. not only demonstrated a dramatic effect on the reaction rate but also showed a significant effect on the wettability of the films. A higher curing temp. led to a less significant surface enrichment of fluorine, due to the fast immobilization of the cross-linked networks. The mixts. had excellent stability below the deblocking temp. (.apprx. 140 DegC) of blocked isocyanates, while the well-defined FB-NCO enabled an easy adjustment of fluorine concn., both making this approach practically attractive and efficient to prep. low surface energy films by using small amts. of fluorine. [on SciFinder (R)