Water resistance improvement of filter paper by a UV-grafting modification with a fluoromonomer

This work describes the surface modification of filter paper by a photoinduced grafting process involving a poly(oxetane) acrylic oligomer with short perfluoroalkyl chains. This modifier avoids the safety, environmental and health concerns of conventional long perfluoroalkyl-chain chemistries, without sacrificing their key performance features. Therefore the work provides an alternative to existing processes aiming to make the paper hydrophobic: the chemicals used are safe, the proposed functionalisation process is rather simple and inexpensive, moreover can be adapted to paper making plants. The experiments show that the grafting induced by UV irradiation changes the surface composition of the samples as assessed by surface spectroscopies and other measurements. As a result of the surface modification, water contact angles on treated paper surfaces were as high as 143° approaching superhydrophobicity. Also oleophobicity was improved (=57°), guaranteeing grease and antistain resistance. Surface tension was strongly reduced and water resistance was improved. XPS, static and dynamic contact angles and capillary wetting studies indicate a substantial gradient in surface energy normal to the treated paper surface