Preparation, Surface-modification Of Nano-ZnO Whiskers And Its Application In Polyacrylate Coating

The suitbale technological parameters of synthesizing nano-ZnO whiskers by a one-step wet chemical method with low-temperature in normal pressure were investigated in this paper, and the modification effects of as-prepared nano-ZnO whiskers by built surfactant in different dispersion condition were also studied. The polyacrylate nanocomposite coatings were parepared by the dispersion of nano-ZnO whskers in polyacrylate, the hardness and other basis performance of nanocomposite film were evaluated.Through changing the different synthetic parameters in turn to prepare final products, and characterizing as-prepared products with DSC-TG, XRD, TEM,FT-IR, the best technological parameters of synthesizing nano-ZnO whiskers were attained. 1.2 mg·L^-1 ZnSO₄ was added drop-wise into 3.0 mg·L^-1 NaOH under stirring in baker that was heated at a temperature of 55°C in thermostat water bath, following that, 0.01 mg·L^-1 C₁₈H₂₉NaO₃S (DBS) was introduced into the aforementioned solution. In the monitoring of pH meter, the pH value of reaction mixture was adjusted to above 9 though controlling the amount of ZnSO₄ added. 2 hours later, the precursor was harvested by filtering under vacuum and washing 3 to 5 times with distilled water and absolute ethanol, finally, the naonsized ZnO whiskers was attain after the precursor was dried in a vacuum oven 4h at 80°C. Depending on the synthetic conditions used, ZnO can be formed directly in aqueous solution without calcination. Transmission electron microscope (TEM) observation reveales that nano-ZnO whiskers are needle-like or rod-like morphology, they have diameters ranging from 30 to 50 nm and lengths up to 400nm. The nano-ZnO whiskers show high crystalline pattern, and all the diffraction peaks can be well assigned to the hexagonal-phase ZnO reported in the literature (Wurtzite-type, space group P63mc), the calculated cell parameters of a₀ and c₀ are 3.25 and 5.21·, respectively. None other phases can be observed in the patter, verifying that the sample is phase-pure. The HRTEM image shows the lattice spacing of 0.26nm, corresponding to a lattice constant of the (002) plane of wurtzite structured ZnO, and implies the preferred growth orientation of ZnO nanorods along the (002) plane.In modification of nano-ZnO whiskers experiments, using DBS / PEG400 which containing 30% DBS as built modifying agent, controlling the concentration of DBS / PEG400 is 400mg·L^-1, and agitating for 60min, the best effects of modification can be gotten. The absorbance of modified nano-ZnO whiskers dispersion is higher than that of unmodified, dispersion and stability in system is also better.The polyacrylate nanocomposite coatings were parepared through dispersing the nano-ZnO whiskers into polyacrylate, After detected some basic performance of the composite coating, we attained the conclusion that, the composite coatings with 6% nano-ZnO whiskers contained have the best comprehensive performance, not only film hardness is strengthened, stain-resisting and scrub resistance of the coating are much increased, but also the coating's thixotropy and storage stability are clear improved.