Wang Zheng, Liu Mei-Chen, Chang Zhi-Yuan, Li Hui-Bo
Department of Radiochemistry, China Institute of Atomic Energy Beijing 102413 China
RSC Adv. 2021 Jul 20;11(41):25158-25169. doi: 10.1039/d1ra04296c. eCollection 2021 Jul 19.
In this research, the graft modification mechanism of coupling agent vinyl triethoxysilane (KH-151) to macroporous silica gel was studied using a combination of multiple methods. SEM, FTIR, RAMAN, NMR and XPS were used to characterize the silica gel before and after grafting, determining the mechanism of the grafting reaction of the silane coupling agent. On this basis, the grafting rate of the coupling agent was accurately calculated by TGA weight loss. From the results of characterization, it can be seen that the coupling agent molecules have two connection types on the surface of silica gel, and the ratio of the two types is 43.51% and 56.49% respectively. The influences of hydration degree of the silica gel, coupling agent dosage and reaction temperature on the grafting rate were explored, and the optimal reaction conditions for the modification of macroporous silica gel were determined by the coupling agent through orthogonal experiments, that is, the hydration degree of silica gel of 10%, a coupling agent dosage of 12 mL, and a reaction temperature of 80 °C. Under optimal reaction conditions, the average grafting rate of the coupling agent vinyl triethoxysilane (KH-151) on macroporous silica gel is as high as 91.03%.
本研究采用多种方法相结合的方式，研究了偶联剂乙烯基三乙氧基硅烷（KH - 151）对大孔硅胶的接枝改性机理。利用扫描电子显微镜（SEM）、傅里叶变换红外光谱仪（FTIR）、拉曼光谱仪（RAMAN）、核磁共振仪（NMR）和X射线光电子能谱仪（XPS）对接枝前后的硅胶进行表征，确定硅烷偶联剂的接枝反应机理。在此基础上，通过热重分析（TGA）失重准确计算偶联剂的接枝率。从表征结果可以看出，偶联剂分子在硅胶表面有两种连接方式，两种方式的比例分别为43.51%和56.49%。探讨了硅胶的水化程度、偶联剂用量和反应温度对接枝率的影响，并通过正交实验确定了偶联剂改性大孔硅胶的最佳反应条件，即硅胶水化程度为10%，偶联剂用量为12 mL，反应温度为80℃。在最佳反应条件下，乙烯基三乙氧基硅烷（KH - 151）偶联剂在大孔硅胶上的平均接枝率高达91.03%。
