Synthesis of mesoporous silica particles with control of both pore diameter and particle size

During last years the interest for nanotechnology and mesoporous silica materials has increased due to benefits that these materials can provide. Typical characteristics of mesoporous materials are a large surface area and pore volume, well-ordered and uniform pores with adjustable pores between 2 and 50 nm. Pore dimensions are comparable to many biological molecules, like enzymes, and may therefore be suitable as a support in enzyme encapsulation The aim of this project was to synthesize mesoporous particles with a fixed pore size in order to optimize enzyme encapsulation. The specific pore size was determined based on previous studies on encapsulated lipase from mucor miehei where the optimal pore size was found to be 9 nm. Through this project different synthesis has been studied, different types of surfactants have been used (Pluronic 123, CTAB) as well as different types of silica sources such as TEOS or sodium silicate solutions. The synthesis conditions have been varied in order to study the effect on the particle and pore size. In this work really small particle sizes were synthesized. Spherical 40 nm nanoparticles was obtained using octane as a hydrophobic support and styrene as a mesoporous template. However, the pore structure was rather slit-shaped than cylindrical. A perfect pore structure and size was reached using a sodium silicate solution as silica source, pluronic 123 as a pore template and an aging period of 24 hours at 180°C. The particles obtained in this synthesis varied with a diameter up to values around 200 nm.