Using Cyclohexanol as a Co-Surfactant in the Synthesis of New Mesoporous Silica Particles

In the synthesis of mesoporous silica particles، the geometry، pore size، and specific surface area and pore volume of the particles can be greatly influenced by selected media and method، selection of co-solvent and co-surfactant. In this study، new SPB particles (silicone mesoporous particles، prepared by sol-gel method using block copolymers as template) were synthesized in a water/n-octane system from the mixture of two copolymers based on poly (ethylene oxide) -b-poly (propylene oxide) -b-poly (ethylene oxide) (PEO-b-PPO-b-PEO) and poly (propylene oxide) -b-poly (ethylene oxide) -b-poly (propylene oxide) (PPO-b-PEO-b-PPO) triblock copolymers. Tetraethyl orthosilicate (TEOS) as precursor، cyclohexanol as co-surfactant، n-octane as co-solvent and citric acid catalyst were used. The specific surface area and pore volume، pore diameter، morphology، microstructure and porosity of the SPB particles were characterized by X-ray diffraction (XRD)، nitrogen adsorption-desorption (BET method) and scanning electron microscopy (SEM). The obtained results revealed that، using the mixture of two block copolymers in the synthesis of SPB1،2 particles، could produce mean pore diameters around 9 nm and control the pore size distribution of silica particles from non-normal to a normal distribution. Furthermore، the effect of chair conformation of cyclohexanol as a large co-surfactant on the mixed block copolymers due to increase in the uniformity and yield of the SPB1،2 mesoporous silica particles compared to the SPB1 particles، there is approximately a two fold increase in SPB1،2 particle yield. In this regard، the effect of cyclohexanol and the second block copolymer in making the new templates and micellization process were discussed.