硅胶整体柱制备及其穿透孔调控

Preparation of SiO_(2) Monolith and Adjustment of Its Through Pores

以四甲氧基硅烷为原料、冰乙酸为催化剂、聚乙二醇(PEG)为致孔剂,采用溶胶-凝胶结合相分离技术制备硅胶整体柱。详细探讨了水浴陈化温度、溶胶pH值及PEG用量对材料内部结构和形貌的影响。研究发现,水浴陈化温度及溶胶pH值主要影响凝胶化时间,当陈化温度过低及pH值过小时,凝胶时间过长,材料内部形成细颗粒堆积体;pH为3.0时,能够得到较好的双连续结构,但随pH值的增大凝胶时间迅速缩短,材料穿透孔(大孔)孔径又逐渐减小;PEG用量主要影响相分离速度,PEG用量低于0.25 g时,无法有效诱导相分离产生,随着PEG用量的增加,硅胶整体柱穿透孔孔径呈现先增大后减小的趋势。

SiO_(2) monolith has been prepared by sol-gel and phase separation technique.Tetramethoxysilane(TMOS)was used as a silica source,aqueous solution of acetic acid was used as a catalyst for hydrolysis and poly(ethylene glycol)(PEG)was used as a porogen during the preparation process.The effects of aging temperature,pH value and PEG content on the through pores of the prepared SiO_(2) monolith have been investigated intensively.It has been found that the aging temperature and pH value mainly affect the gelation time.When the aging temperature was too low and the pH value was too small,the gel time was long accordingly,and fine particles accumulated inside the material.When pH was 3.0,a good bi-continuous inner structure was obtained.However,when the pH value increased continuously,the gel time shortened rapidly and the through pore(macropore)size of the prepared SiO_(2) monolith gradually decreased.The amount of PEG mainly affects the phase separation speed.When PEG amount was 0.25 g or less,almost no phase separation occurred.With the increasing amount of PEG added to the reaction solution,through pore size of the prepared SiO_(2) monolith increased firstly and then decreased.