【摘要】 以硅酸乙酯为前驱体,通过水解法制备SiO2溶胶,系统研究了SiO2胶体的溶胶-凝胶转变过程。讨论了不同参数(如pH值、温度、硅酸乙酯的浓度等)对溶胶体系胶凝时间的影响,并对该过程的活化能进行了计算。结果表明:在酸性条件下,溶胶分子的生长模式为线性;随pH值增加,体系胶凝时间先增加后减少,拐点在pH等于2处;活化能与体系的pH有关。同时对上述结果从化学键、电荷密度、反应机理等方面进行了合理的解释。更多还原

【Abstract】 Kinetics and influencing factors (such as pH value, TEOS concentration and tempe rature) of sol-gel transition of SiO 2 sol prepared through the hydrolytic met hod were studied. The activated energy of the transition was calculated also. Th e results showed that the molecule growth mode of sol is linear in acid conditio ns. A gradual increase in coagulation time of sol is observed for pH value lower than 2. Further increase of PH value slightly decreases the coagulation time. R eaction activated energy is related to pH value of systems also. The results wer e explained by chemical bond, charge density and reaction mechanism.更多还原