Enhancing the low surface energy properties of polymer films with a dangling shell of fluorinated block-copolymer

Stabilizing long-term, low energy surface properties is a key issue in designing fluorinated polymer network, because the fluorinated surface could reorganize or hydrolyze upon contact with water. Here we report an exploring to enhance the low energy surface performance by bonding a dangling shell of fluorinated block copolymer, poly((1H,1H,2H,2H-perfluorodecyl acrylate)-b-poly(caprolactone) (PFDA-b-PCL)), to the polyurethane network. The PFDA and PCL block are the fluorinated shell and the dangling chain, respectively. The fluorinated shell protects the surface from rearrangements and hydrolysis when in contact with water, while the soft polyester block provides the required flexibility for fluorinated components to segregate to the surface. Surfaces with water contact angle up to 120° and surface energy down to 18   mN/m were obtained. We then evaluated the effects of fluorinated species on the surface properties of the polyurethane network both with and without the fluorinated shell or polyester spacer. The surfaces functionalized with the fluorinated dangling shell are highly hydrophobic and exhibited better hydrophobic stability. The oligoester spacer connecting the fluorinated shell to the polymer network is critical for the segregation and rebuilding of low energy surfaces.