Unconscious factors affecting physical characteristics of sol–gel-derived monodispersed silica spheres

• Published in: Journal of sol-gel science and technology 2022-12, Vol.104 (3), p.512-518
• Main Authors: Enomoto, Naoya, Nishimura, Yusaku, Inada, Miki
• Format: Article
• Language: English
• Subjects: Aging; Alcohols; Alkoxides; Ceramics; Chemical partition; Chemistry and Materials Science; Composites; Dissolution; Glass; Inorganic Chemistry; Invited Paper: Fundamentals of sol–gel and hybrid materials processing; Materials Science; Moisture effects; Nanoparticles; Nanotechnology; Natural Materials; Nucleation; Optical and Electronic Materials; Partitioning; Physical properties; Silicon dioxide; Sol-gel processes; Sol-Gel Research in Japan; Solvents; Spheres; Surfactants; Synthesis
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-022-05917-7

Syntheses of monodisperse silica spheres (MSS) and monodisperse mesoporous silica spheres (MMSS) were studied focusing on the age of starting solutions, the solvent partitioning, and the surfactant dissolution as unconscious process factors. Aging of clear and transparent starting solutions decreased nucleation and increased the size of MSS, while the aging effect was opposite in the case of MMSS. Alcohols were used as co-solvent for alkoxides and water to dilute them. Partitioning ratio of alcohols was also a factor that changes the sphere size. Even when a surfactant is soluble in water and alcohol to readily form a transparent starting solution, the clusters consisting of solute and solvent molecules or their molecular level dissolution states may vary during aging, and thus could be a factor affecting the nucleation of nanoparticles. Aging of a methanolic solution of tetramethylorthosilicate (TMOS) containing a surfactant (C16TAC; cetyltrimethylammonium chloride) resulted in unfavorable formation of irregular (non-spherical) particles probably due to the interaction between TMOS and a moisture in the surfactant during aging. Syntheses of monodisperse silica sphere (MSS) and monodisperse mesoporous silica sphere (MMSS) were studied focusing on the age of starting solutions, solvent partitioning, and surfactant dissolution as unconscious process factors. Aging of clear and transparent starting solutions decrease nucleation and increase the sphere size of MSS, while the aging effect is opposite in the case of MMSS. The decrease in the MMSS size due to aging was the largest when the methanol solvent was used only to dissolve water and surfactant and then reacted with a pure alkoxide free from the solvent (10s/0). Highlights Aging of starting solutions for synthesis of monodisperse silica spheres (MSS) increased the size of MMS. Aging of starting solutions for synthesis of monodisperse mesoporous silica spheres (MMSS) decreased the size of MMSS. The decrease in the MMSS size due to aging was dependent on the solvent partitioning and surfactant dissolution.