Synthesis Of Aqueous Polyurethane Dispersions Modified By Fluorine-containing Acrylate And Characterization Of Their Film Morphologies

Aqueous Polyurethanes(PU) were used widely in coating, adhesive, weaven finishing and so forth in recent years with excellent softness, stiffness, adhesive, rubbness and other properties.At the same time, Aqueous Polyurethanes were accepted popularly by many people all over the world because of the environmental friendship.But the serious problem for aqueous Polyurethanes is the hydrophilic surface of the films because the pendant carboxylic salt groups located on the surface of the aqueous Polyurethanes Dispersion(PUD) films materials.So,there are some problems for how to resolve the hydrophobic surface of the films .namely how to remove carboxylic salt groups away from the surface of PUD films, how to disperse well in water and not to influence excellent properties of PUD films.In order to resolve those problems , Fluorine-containing acrylates were introduced to PUD because of the very lower surface energy of -CF3,then two properties can be obtained by us.Firstly,the PUD will have the very lower surface energy with the same surface properties of perfluoridecarborn polymer through that the fluorines enriched in the film surface.Secondly,the properties of PUD can be preserved.In the study, A hydroxyl-terminal fluorine-containing macromonomer with average molecule weight about 6000 was synthesized by radical copolymerization of dodecafluroheptyl acrylate with mercaptoethanol as chain-transfer agent. A-B-A tri-blocked polymer was obtained by reacted the macromonomer with NCO-terminal prepolymer with build in hydrophilic groups. Aqueous A-B-A polymer dispersion was prepared by dispersing the tri-block polymer in water. At the same time ,we had also synthesized aqueous Polyurethane Dispersion modifiedby containing-fluorine acrylate through seed emulsion polymerization with Polyurethane emulsion as seed emulsion.The structure dispersion and the morphology of its film were investigated by TEM,XPS, ATR, Contact angel. TEM study shows that the dispersion has a core-shell structure, XPS, ART and Contact angel studies show that the fluorine groups were enriched in the film surface, but also the TEM study shows that the polymer film exhibit a "sea-island" morphology, where fluorine-containing polyacrylate was the dispersed "island" and polyurethane was continuous phase "sea".So we can resolve those problems for hydrophobic surface of the films, that flourine-containing A-B-A tri-block Polyacrylates-PUD can be dispersed well in water ,and not to influence own excellent properties of PUD films.