Facile hydrophobic modification of hybrid poly(urethane-urea)methacrylate aqueous dispersions and films through blending with novel waterborne fluorinated acrylic copolymers

Aqueous dispersions of fluorinated particles (PBF) based on copolymers of butyl acrylate (BA) with 2-(perfluorononenyloxyl)ethyl methacrylate (FNEMA), 2,2,3,3-tetrafluoropropyl acrylate (TFPA), and 2,2,3,3,4,4,5,5-octafluoropentyl acrylate (OFPA), respectively, were synthesized by emulsion polymerization in the presence of unfluorinated and fluorinated anionic surfactant binary mixtures. These fluorinated dispersions showed good to excellent colloidal stability, as determined by freeze-thaw, centrifugation, and critical coagulation concentration measurements. Blending of small amounts (1-10 wt%) of PBF latex particles with a waterborne hybrid poly(urethane-urea)-methacrylate (PUUA) resulted in a series of slightly fluorinated modified PUUA (MPUUA) with good film forming properties and low surface energy. The precursor PUUA had been synthesized separately by simultaneous chain extension of a poly(ester-urethane)-diisocyanate with ethylenediamine and soapless free radical polymerization of methyl methacrylate (MMA) swelling the resulting branched or slightly crosslinked poly(urethane-urea) (PUU) self-dispersible ionomer particles. The results of dynamic light scattering and Zeta potential measurements suggest that merging of PUUA and PBF particles and either engulfing or interdiffusion of the incompatible macromolecular phases occurred to some extent already in the colloidal state. Highly hydrophobic films with surface energy as low as 17 mJ/m2 were obtained upon hybridization of PUUA with the FNEMA copolymer. Thermal annealing allowed to minimize the effects of fast surface dynamics leading ultimately to water absorption, and to promote synergistic enhancement of the resulting hybrid film hardness, as required for coating applications