Preparation And Application Of Polyacrylate/Hollow Zinc Oxide Composite Emulsion

Polyacrylate resin is one of the most widely used and important film-forming materials in leather finishing because of its outstanding physics performance. However, the poor hygienic properties of dense polymeric finishing film significantly affect the wearing comfort for leather. Hollow zinc oxide (ZnO) particles have attracted extensive interest owing to their inherent cavity structures, excellent photoelectric performance, and biocompatibility.In this research, various hollow ZnO particles were synthesized. The effects of reaction conditions on morphology of hollow ZnO structures were investigated. The structure and morphology of as-obtained hollow ZnO particles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller surface area. Then, polyacrylate/hollow ZnO composite emulsion was obtained by physical blending of polyacrylate emulsion and hollow ZnO particles. The preparing conditions of hollow ZnO particles were optimized with water resistance, water vapor permeability and mechanical properties of composite film as indexes. Based on above research, the main contents are listed as follows.Hollow columnar-like ZnO particles were successfully prepared by hydrothermal method. The diameters and the length of hollow columnar-like ZnO were 400-500 nm and 800-1000 nm, respectively. The shell of hollow columnar-like ZnO had mesoporous structure with average pore size of 25.11 nm. The specific surface area and pore volume of hollow columnar-like ZnO were 6.54 m2/g and 0.04 cm3/g, respectively. When the organic solvent was ethanol/ethylene glycol, the reaction pH was 11.0, the reaction temperature was 92 ℃, the reaction time was 9 h, the morphology of hollow columnar-like ZnO and the performance of corresponding polyacrylate/hollow ZnO composite film were optimal. Compared with polyacrtylate film, the water resistance, water vapor permeability, tensile strength and elongation at break of polyacrylate/hollow columnar-like ZnO composite film increased by 38.10%, 103.91%,144.53% and 79.52%, respectively.Hollow spherical-like ZnO particles with nano-sheets were successfully prepared by alkali etching process. The diameters of hollow spherical-like ZnO were 2-2.5 μm. The shell of hollow spherical-like ZnO had mesoporous structure with average pore size of 17.29 nm. The specific surface area and pore volume of hollow spherical-like ZnO were 13.16 m2/g and 0.06 cm3/g, respectively. When the precipitation agent was HMTA, the concentrations of trisodium citrate was 4 mM, the reaction pH was 8.5, the reaction temperature was 95 ℃, the morphology of hollow spherical-like ZnO and the performance of corresponding polyacrylate/hollow ZnO composite film were optimal. Compared with polyacrtylate film, the water resistance, water vapor permeability, tensile strength and elongation at break of polyacrylate/hollow spherical-like ZnO composite film increased by 42.87%,146.47%,54.51% and 45.31%, respectively.Hollow urchin-like ZnO particles were successfully fabricated by a two-step method. The diameters of hollow urchin-like ZnO and the length of their nanorods were 1.6-2.9 μm and 100-350 nm, respectively. The shell of hollow urchin-like ZnO had mesoporous structure with average pore size of 28.58 nm. The specific surface area and pore volume of hollow urchin-like ZnO were 9.34 m2/g and 0.07 cm3/g, respectively. When the annealing temperature was 600 ℃ in step 1, the reaction time was 1 h in step 2, the reaction temperature was 95 ℃ in step 2, and molar ratio of Zn(NO3)2 to HMTA was 1:0.2 in step 2, the morphology of hollow urchin-like ZnO and the performance of corresponding polyacrylate/hollow ZnO composite film were optimal. Compared with polyacrtylate film, the water resistance, water vapor permeability, tensile strength and elongation at break of polyacrylate/hollow urchin-like ZnO composite film increased by 36.74%,127.03%,3.44% and 112.50%, respectively.The comprehensive performances of three composite emulsions and their application in leather finishing were that polyacrylate/hollow spherical-like ZnO composite emulsion is the best, while polyacrylate/hollow columnar-like ZnO composite emulsion is the worst.