In situ attenuated total reflectance Fourier transform infrared spectroscopy is used to monitor the chemical evolution of the mesoporous silica SBA-15 from hydrolysis of the silica precursor to final silica condensation after the particle formation. Two silica precursors, tetraethyl orthosilicate (TEOS) or sodium metasilicate (SMS) were used, and the effects of additive (heptane and NH₄F) concentrations were studied. Five formation stages are identified when TEOS is used as the precursor. The fourth stage correlates with the appearance and evolution of diffraction peaks recorded using in situ small angle X-ray diffraction. Details of the formed silica matrix are observed, e.g. the ratio between six-fold cyclic silica rings and linear bonding increases with the NH₄F concentration. The TEOS hydrolysis time is independent of the NH₄F concentration for small amounts of heptane, but is affected by the size of the emulsion droplets when the heptane amount increases. Polymerization and condensation rates of both silica precursors are affected by the salt concentration. Materials synthesized using SMS form significantly faster compared to TEOS-materials due to the pre-hydrolysis of the precursor. The study provides detailed insights into how the composition of the synthesis solution affects the chemical evolution and micellar aggregation during formation of mesoporous silica.

原位衰减全反射傅立叶变换红外光谱用于监测中孔二氧化硅SBA-15从二氧化硅前体的水解到颗粒形成后最终二氧化硅缩合的化学演变。使用了两种二氧化硅前体，原硅酸四乙酯（TEOS）或偏硅酸钠（SMS），并研究了添加剂（庚烷和NH ₄ F）浓度的影响。当将TEOS用作前体时，确定了五个形成阶段。第四阶段与使用原位小角度X射线衍射记录的衍射峰的出现和演变有关。观察到形成的二氧化硅基质的细节，例如，六倍环状二氧化硅环之间的比例和线性键合随NH的增加而增加₄ F浓度。对于少量庚烷，TEOS水解时间与NH ₄ F浓度无关，但是当庚烷量增加时，TEOS水解时间受乳液液滴尺寸的影响。两种二氧化硅前体的聚合和缩合速率均受盐浓度的影响。由于前体的预水解作用，与TEOS材料相比，使用SMS合成的材料形成速度要快得多。该研究提供了有关中孔二氧化硅形成过程中合成溶液的组成如何影响化学演化和胶束聚集的详细见解。