Low Surface Energy Coatings from Partially Fluorinated Photocurable Solventless Liquid Oligoesters

摘要

Self-stratifying coatings capable of producing multilayer structure in one operation have been of increasing research interest recently. We have developed a solventless (environmentally friendly) self-stratifying system on the basis of a partially fluorinated hydroxyl end-capped solventless liquid three-armed oligoester by thermal curing. The hydroxyl groups can be further substituted by acrylic double bonds; hence a photocurable liquid oligoester is readily obtained. A conventional photoinitiator containing 2-hydroxy-2-methylpropiophenone was used to cure the liquid oligoester. As the fluorine content increases from 0 to about 1.57 wt%, the surface energy decreases by about 14 mN/m. The fluorine level in the outer few nanometers is significantly greater than that in the bulk, as revealed by XPS studies. The driving force for the surface segregation of fluorinated species comes from the big difference in surface energy between the oligoesters and their fluorinated counterparts.