title: Preparation of mesoporous submicrometer silica capsules via an interfacial sol-gel process in inverse miniemulsion.
abstract: Mesoporous silica capsules with submicrometer sizes were successfully prepared via the interfacial hydrolysis and condensation reactions of tetraethoxysilane (TEOS) in inverse miniemulsion by using hydrophilic liquid droplets as template. The inverse miniemulsions containing pH-controlled hydrophilic droplets were first prepared via sonication by using poly(ethylene-co-butylene)-b-poly(ethylene oxide) (P(E/B)-PEO) or SPAN 80 as surfactant. TEOS was directly introduced to the continuous phase of an inverse miniemulsion. The silica shell was formed by the deposition of silica on the surface of droplets. The formation of capsule morphology was confirmed by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The mesoporous structure was verified by nitrogen sorption measurements. The specific surface area could be tuned by the variation of the amount of cetyltrimethylammonium bromide (CTAB) and TEOS, and the pore size by the amount of CTAB. The influences of synthetic parameters on the particle size and morphology were investigated in terms of the amount of CTAB, pH value in the droplets, TEOS amount, surfactant amount, and type of solvent with low polarity. A formation mechanism of silica capsules was proposed.
authors.affiliation: College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou, China. caozhihai@hznu.edu.cn
authors.forename: Zhihai
authors.initials: Z
authors.lastname: Cao
authors.forename: Lizi
authors.initials: L
authors.lastname: Dong
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Yue
authors.initials: Y
authors.lastname: Shang
authors.forename: Dongming
authors.initials: D
authors.lastname: Qi
authors.forename: Qun
authors.initials: Q
authors.lastname: Lv
authors.forename: Guorong
authors.initials: G
authors.lastname: Shan
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ziener
authors.forename: Katharina
authors.initials: K
authors.lastname: Landfester
mesh_terms: D002021:Buffers; D002214:Capsules; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D004655:Emulsions; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D055616:Microtechnology / Q000379:methods*; D010316:Particle Size; D044367:Phase Transition; D016062:Porosity; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002021:Buffers; D002214:Capsules; D002593:Cetrimonium Compounds; D004655:Emulsions; D012821:Silanes; D012997:Solvents; D013501:Surface-Active Agents; C040733:tetraethoxysilane; D012822:Silicon Dioxide; D000077286:Cetrimonium