Study On Nano-encapsulating Of Water-borne Polyurethane To Solid And Liquid Particles

In this paper, polyurethane ionomers including amphipathic nanoparticles were prepared by self-emulsifying method. The nanoparticles were used to encapsule a solid or liquid, thus anionic polystyrene/polyurethane (PS/PU) and cationic silicon dioxide/polyurethane (SiO2/PU) nanocomposites dispersions of core-shell type were prepared in-situ. The later are innovative result. The structure-property relationships of polyurethane ionomers and their nanocomposites were studied carefully and a series of analytical methods were established to investigate the structures and phase separations of them.Uncross-linked nanocomposites dispersions presented narrow and continuous particle size distribution, whose mean particle sizes were of nanometer dimension. Obvious core-shell structure could be seen in the particles. The core/shell ratios had a affection on particle sizes, viscosities, conductivities, absorbance and thermal stability. The cross-linked structure affected the particle morphology and properties also.The bulk polymerization process of styrene was studied, that indicated that styrene was cosolvent in anionic polyurethane nanocapsules and heteroazeotropic polymerization occurred directly. When core/shell ratio was higher than 60:100, there were particle's aggregations of some degree. Cationic polyurethane and uncross-linked SiO2/PU nanocomposites were of amorphous phase, however, cross-linked SiO2/PU nanocomposites had crystallinity. d(A)=3.87, 3.58nm indicated that it was cubic system of silicon dioxide.There were more hard segments on the surface of polyurethane and phase mixing between soft and hard segments. The existence of cores and cross-linked structure between core and shell made much effect on the phase behavior of the nanocomposites. It could be found that the physical properties of electrophoresis membrane of epoxy resin were improved by SiO2/PU nanocomposites. Intensity and flexibility of epoxy resin membranes were increased simultaneously.