Strongly amphiphilic wetting behavior for polyurethanes with polyoxetane soft blocks having –CF2H terminated side chains

Two novel polyoxetanes with –CF2CF2H (4F) or –(CF2)3CF2H (8F) terminated side chains were synthesized and characterized by 1H NMR spectroscopy, DSC and GPC. 4F and 8F diols were incorporated in polyurethanes IPDI-BD(40)/4F-8.2 (U-4F-8.2) and IPDI-BD(40)/8F-5.8 (U-8F-5.8), where isophorone diisocyanate (IPDI) and 1,4-butane diol (BD) comprise the hard block (40 wt%) and 4F-8.2 or 8F-5.8 are soft blocks with Mn in kDa. Surface characteristics were evaluated using TM-AFM, XPS and dynamic contact angle (DCA) measurements. In contrast to U-4F-8.2, TM-AFM reveals an interesting phase separated surface morphology for U-8F-5.8 apparently driven by higher F side chain content. A model is proposed to account for contact angle measurements that show reversible, strongly amphiphilic wetting with θadv > 100° and θrec < 40°. Resistance to surface phase separation and related studies suggest the –CF2CF2H moiety is an important candidate for expanding the range of functional groups employed in surface modifiers.