Physical Chemistry, Lund University, Lund, Sweden.
Langmuir. 2012 Aug 7;28(31):11567-74. doi: 10.1021/la3013969. Epub 2012 Jul 23.
A hypothesis about (transient) colloidal stability as a controlling mechanism for particle formation in SBA-15 is presented. The hypothesis is based on results from both in situ and ex situ investigations, including cryogenic transmission electron microscopy (cryo-TEM), UV-vis spectroscopy, and dynamic light scattering (DLS). Cryo-TEM images show that particles grow via the formation of silica-Pluronic-water "flocs", which coalesce in a seemingly arbitrary manner. Despite this, the final material consists of well-defined particles with a small size distribution. We argue that the interface between the flocs and surrounding media is covered by Pluronic molecules, which provide steric stabilization. As the flocs grow, the coverage of polymers at the interface is increased until a stable size is reached, and that regulates the particle size. By targeting the characteristics of the Pluronic molecules, during the on-going synthesis, the hypothesis is tested. The results are consistent with the concept of (transient) colloidal stability.
提出了一种关于（瞬态）胶体稳定性作为 SBA-15 中颗粒形成控制机制的假设。该假设基于原位和异位研究的结果，包括低温透射电子显微镜（cryo-TEM）、紫外-可见光谱和动态光散射（DLS）。低温 TEM 图像显示，颗粒通过硅烷-Pluronic-水“絮体”的形成而生长，絮体以看似任意的方式聚结。尽管如此，最终的材料还是由具有小尺寸分布的定义明确的颗粒组成。我们认为，絮体和周围介质之间的界面被 Pluronic 分子覆盖，提供了空间稳定作用。随着絮体的生长，聚合物在界面上的覆盖度增加，直到达到稳定的尺寸，从而调节了颗粒的大小。通过在正在进行的合成过程中针对 Pluronic 分子的特性进行靶向，对假设进行了测试。结果与（瞬态）胶体稳定性的概念一致。
