Polyamine-Functionalized 3D Macroporous Silica One-Pot Prepared Through Supramolecular Emulsifier Aided Ex-Situ, Gradient and Directed Growth of Silica

Abstract

The functionalization of porous silica with polyamine (typically branched polyethyleneimine (PEI)) usually suffers from drawbacks such as sharply (typically 100-fold) decreased surface, insufficient and tedious surface functionalization. Here a cost-effective route which mostly overcomes these drawbacks is presented. Minor glycidyloxypropyltrimethoxysilane (GPTOS) along with major tetraethoxysilane (TEOS) is dispersed in water with the aid of a supramolecular emulsifier of PEI/sodium dodecylbenzene sulfonate (SDBS), and the resulting emulsion directly affords open, PEI-dictated and 3D macroporous silica after standing and subsequent vacuum drying. The route is featured in that 1) Opening pores afford because of the ex-situ reaction of silicates; 2) The supramolecular emulsifier is tolerant to the demulsification of reaction-released alcohols, and allows only the outer PEI shell accessible to silica growth; 3) The silica surface is sufficiently and robustly dictated by nearly monolayer PEI because the preferential evolution of GPTOS allows PEI to be immobilized by a few bonds to the silica framework, leaving most PEI amines intact; 4) the specific surface area of the PEI-dictated material is about one order higher than a typical and similar product. The as-prepared macroporous material quickly and efficiently separate water from oil and oil-in-water emulsions.