Environmentally benign and cost-effective silicification: from water glass to nanostructured silica by poly(ethyleneimine) mediation

Abstract

Silica deposition by mediation of aggregated linear poly(ethyleneimine) (LPEI) from a basic aqueous solution of sodium silicate can produce ordered silica with fibrous bundle structure hybridized with LPEIvia zero-emission of organic by-products. By changing the polymer concentration and pH value of the aqueous solution of sodium silicate, we were able to control the architecture of the resulting silica. This process is environmentally benign and inexpensive and thus would be feasible for industrial scale-up for the fabrication of silica nanomaterials. In addition, a typical fibrous silica bundle was characterized by fluorescence X-ray analysis, solid state ²⁹Si (CP/MAS) NMR, TG/DTA, thermo-calcination, N₂/He adsorption–desorption experiments, and high resolution TEM. Interestingly, the fibrous silica bundle, which contains about 25% LPEI, served as an effective nanoreactor to reduce metal ions into nearly cluster-size metallic nanoparticles inside the silica.