title: Transient colloidal stability controls the particle formation of SBA-15.
abstract: 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.
authors: Physical Chemistry, Lund University, Lund, Sweden.
authors: Juanfang
authors: J
authors: Ruan
authors: Tomas
authors: T
authors: Kjellman
authors: Yasuhiro
authors: Y
authors: Sakamoto
authors: Viveka
authors: V
authors: Alfredsson
mesh_terms: D003102:Colloids; D020285:Cryoelectron Microscopy; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D020442:Poloxamer / Q000737:chemistry*; D058105:Polymerization; D053838:Scattering, Small Angle; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D003102:Colloids; C509969:SBA-15; D014867:Water; D020442:Poloxamer; D012822:Silicon Dioxide