Gelation Process Of The Gemini Silica Sol And Its Application

The gemini cationic compounds could strongly adsorb from aqueous solutions onto the silica sol particle surfaces, which charged with negative. According to this absorb rule, a hybrid material could be prepared. And there were some studies had been reported about the application of this new functional material in the tertiary oil recovery and textile field. In this paper a hybrid material called gemini silica sol was prepared by sol-gel method with tetraethoxysilane as precursor and Ethylene-bi(soctadecyl dimethyl ammonium chloride)(EBODAC) as additive The properties, gelation process in presence of the inorganic salts of the gemini silica sol was studied. The application of the sol on the anti- ultraviolet and anti-bacterial compound finishing of the cotton fabric was also discussed.In the preparation of the cationic sols, the influence of the reactant ratio, reactant species and preparation condition on the sol characters had been investigated by analyzing the viscosity and gelation time of the sol. As a result, a kind of gemini silica sol could be prepared by mixing TEOS, EtOH, H2O, HCl and EBODAC in a mole rotating of 1:8:5:0.04:0.05, and stirring the mixture at 50°C for 6 h. The Zeta potential of the prepared sol was about 23.31mV and the diameter was about 5.82nm. FT-IR spectrum of the sol confirmed that Si-O-Si band was formed, but no chemical bands were found between the ECOCAD and the sol.Inorganic salt was one of the most important factors that could influence the gelation process of sol. In this paper, different kinds and dosages of inorganic salts were added into the sol. The gelation regularity and mechanism of the sol in presence of the inorganic salts were alalysized. So we could regulate the gelation speed of the sol by adding inorganic salts in the future study. The result resolved that the NaCl,KCl,MgCl2,CaCl2 of 0.2mol/Land NaCl,NaBr,NaI,NaNO3,NaAc,NaOH,Na2CO3,Na3PO4 of 0.003mol/L could promote the gelation of the sol, but FeCl3 of 0.003mol/L could delay the sol gelation. The promote effect of the cationic in the inorganic salt was determined by its hydrated radius. The larger the hydrated radius, the stronger the promote effect was. As the anion charged more negative ion or had smaller radius, its promote effect to the sol gelation could be enhanced.A gemini SiO2/TiO2 composite sol could be prepared by compounding the gemini silica sol and TiO2 together. And this sol could be applied on the anti-ultraviolet and antibacterial finishing of the cotton fabric. The effect of the Si/Ti ratio, concentration of the sol, bapad-dry-cure process, dosage and species of coupling agent on the properties of antibacterial,anti-ultraviolet,washing fastness , whiteness and strength of the treaded fabric was investigated. The results showed that the optimum condtions for the finishing of the fabric was Si/Ti ratio 4:1, concentration of the sol 0.3mol/L, two dipping androlling of pick-up 70%, baking under 160℃for 3min, coupling agent was KH-570,of which the concentration was 0.2mol/L. At this monment, the UV transmittance of the treaded fabric was under 2%, 4% and 15% at the wave band of UVA, UVB and UVC, respectively. The inhibitory rate of the treaded fabric was up to 91.7%, and the whiteness and strength of the tread fabric changed little comprised with the untreated. After 30 times washing, the UV transmittance of the treaded fabric at 297nm was 96.8%, the inhibitory rate was also as high as 80.7%, which meant that the anti-ultraviolet property, antibacterial property and washing fastness of treaded fabric were excellent.