Study On The Superhydrophobic In-situ Modification Of Precipitated Silica And Its Application In UV-curable Coatings

Superhydrophobic surface has a bright prospect of applications on building coatings,navigation, pipeline transportation, vehicles and biomedical materials because of its excellentsuperhydrophobic and self-cleaning properties. Up to now, many superhydrophobic surfaceshave been prepared via many kinds of methods. However, most of the methods are notappropriate for industrial production for their expensive materials costing, complex process,or poor mechanic intensities of coatings. So it is essential to develop a simple and low-pricemethod to prepare superhydrophobic materials.UV-curable coatings are a kind of non-pollution and environment friendly coatingswhich has been highly developed in recent years. The preparation of surface-functionalcoatings through modiifcation of silica is becoming a hot research spot in coating ifeld. Thereis a bright prospect and marketing potential.In this paper, ifrstly, the superhydrophobic coatings with micrometer and nanometerrough composite structure were prepared by using the method of in-situ modiifcation ofprecipitated silica by TEOS and VTES through adjusting the curing temperature and time.The structure of silica before and after modiifcation was analyzed by Fourier transforminfrared spectroscopy (FTIR)，and the surface morphology of the coating was observed byScanning electronic microscopy (SEM). Secondly, the in-situ reaction of VTES modiifedsilica was introduced to the preparation process of UV-curable coating through thepolymerization of active monomers (acrylate and VTES) initiated by UV-irradiation, andthen grafting modiifcation of silica with VTES under high temperature, and the UV-curedhybrid superhydrophobic coatings were obtained. The structure variation of the coatingsbefore and after curing was investigated by FTIR. The influence of silica in the hybridcoatings on thermal stability of the coatings was investigated by thermogravimetry (TGA).The surface morphology of several kinds of UV-cured hybrid superhydrophobic coatings wasinvestigated by SEM and AFM. Moreover, the mechanical properties, water resistance andacid-base resistance property of these hybrid coatings were also investigated.The results show that the coatings prepared by in-situ modiifcation of precipited silicawith TEOS and VTES exhibit excellent hydrophobicity. The water contact angles are about165°with slide angles less than1°. The temperature and time of drying and reaction play aconclusive role in the forming of micrometer and nanometer rough composite structure in thecoating surface. The introduction of the in-situ modiifcation reaction of silica to the UV-curable coaitngs can form rough composiet surface structure without influencing theUV-initiating polymerization, and the coatings show superhydrophobic property and high UVcuring eiffciency. The superhydrophobic modiifcation process of precipitated silica will notinduce any change of its amorphous structure according to XRD results. Besides，these hybridcoatings all exhibited excellent acid-base resistance.