Preparation of hierarchically mesoporous silica monolith using two components of poly(ethylene glycol) as cooperative dual-templates

Abstract

In this work, two components of poly(ethylene glycol) (PEG) are used as dual-templates for facile and cost-effective preparation of hierarchically mesoporous silica monoliths (HMSMs) with controllable mesostructures and co-continuous macrostructures from low-toxicity tetraethoxysilane. The influence of different preparative parameters on the porous structures was studied, including the proportions of PEGs and acidity. The typical HMSM (PEG-1.5/0.5) with skeleton mesopore size of 6.3nm, skeleton thickness of 1.25μm and macropores of 1.87μm can be obtained. The total pore volume and high surface area reach 711m2g−1 and 3.37cm3g−1 (including mesopore volume of 0.93cm3g−1), respectively. The PEG400 and PEG35k are proved to play cooperative roles as dual-templates in harnessing the mesoporous skeletons and co-continuous macrostructures. Interestingly, in such preparation system, the use of PEG400 is found to be play key role in inducing the formation of skeletons with relatively large mesopores, while the amount of PEG35k is a more sensitive factor in shaping the macroporous structures. This work is believed to open a new path to engineering the macroporous and mesoporous structures via the TEOS/PEG/HCl(aq.) synthesis system.