Study On Surface Modification Of Nano-silica

In this paper ,two kinds of surface modification method(chemical measure and soap-free polymerization ) are used. After the surface of nano-silica was modified, nano-coating is prepared by mixing nano-silica into polyacrylate emulsion. The properties of membrane formed have been proved to be improved. More emphasis will be put on analyzing stain resistance and scrubbing resistance.Nano-silica in aqueous solution(solid content w =25%-30%, particle size s=8-15nm, PH=9) has been prepared by silicon. Then two modification measures are used to modify nano-silica particle. According to chemical method , modifier is got by silane coupling agent (WD-30) grafted with PEG of different molecular, which make the surface of nano-silica amphiphilic and improve the interface of nano-silica. Soap-free polymerization method means monomers(MMA) polymerize around the surface of nano-silica without soup, absorbed by the force of surface. By the means of TEM and potential test , the improvement of dispersal of nano-silica has been proved: particle size of aggregates decreased from 120-200nm to 80nm.Effects of modification measure and the content of nano-silica to experiment generally chemical measure, with higher chemical band force , will lead to better results than soap-free polymerization measure. To chemical measure , the higher molecular of PEG is, the better result will be got; to soap-free polymerization ,on the contrary , the content of PMMA enwrapping nano-silica effect few on results, which is obviously shown in data of stain resistance. With the horizon in rate of pigment and filler, high content of nano-silica will be benefit to result of experiment, for example , rigidity will increase with the content of nano-silica raising.Making up nanopaint mixed with nano-silica ,the improvement of its properties has been tested. The mechanic property of membrane formed increased , such as tensile strength, elongation at break, surface rigidity;The scrubbing resistance and stain resistance of the paints has been improved . But it's the limitation that ideal results of properties of waterproofing and UV-screen haven't beengotten. Few disciplinarian can be found from the data of contact angle function and water absorbency.Effects of temperature to stain resistance : with higher circumstance temperature ,stain resistance will be lower, and more easily effected by content of nano-silica.