High Modulus, Low Surface Energy, Photochemically Cured Materials from Liquid Precursors

A new strategy has been developed to achieve durable, low surface tension fluorinated polymeric materials by copolymerizing a tetramethacryloxy-modified perfluoropolyether (PFPE) macromonomer and a fluorinated difunctional cross-linker, 1H,1H,6H,6H-perfluoro-1,6-hexyl diacrylate (PFHDA), into very highly cross-linked materials that possess a very high modulus as well as a very low surface energy. The miscibility of the two fluorinated components has been studied by measuring the cloudpoint temperatures. Partially miscible mixtures yielded optically transparent samples after curing at low PFHDA contents (e.g., <40 wt%), and cloudy samples were obtained at high PFHDA contents when cured at room temperature. However, it was possible to achieve optically transparent samples with high PFHDA contents by increasing the cure temperature. The miscibility of these materials has been further studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and atomic force microscopy (AFM). By incorporating PFHDA into the cross-linked system, a low surface energy, very high modulus (up to 458MPa) thermoset could be achieved which is important formany applications including as hard, abrasion-resistant coating materials.