Self-replenishing low surface-energy polyurethane films

Surface segregation is a concept frequently used for obtaining films with desired surface functionality, such as surfaces enriched in low surface-energy species. Low surface-energy films with fluorine-rich surfaces have many desirable properties such as water/oil repellency and low friction coeff., and have been developed via surface segregation of fluorinated species during film formation. However, it has been shown that the fluorine-enriched layer is generally very thin (<20 nm), and the coating may not sustain the low surface-energy character upon mech. abrasion. We have developed a self-replenishing strategy to sustain the low surface-energy character of partially fluorinated polyurethane films: in case of surface damage that leads to the loss of the top layers of the coating, fluorinated tails from sub-layers can reorient themselves to minimize the air/film interfacial energy of the newly created surface. The network mobility and a proper spacer between the fluorinated tail and the cross-linked network have proven to be the key elements in realizing the self-replenishing behavior. [on SciFinder (R)]