Investigations on the surface structure and properties of silica‐polyamine composites on the nanoscales and microscales

Abstract

The structure and properties of silica polyamine composites (SPC) made from microparticles of amorphous silica gel (300-600 microns) and silica nanoparticles (10-20 nm) modified with aminopropyltrimethoxysilane (APTMS), poly(allylamine) (PAA) or poly(ethyleneimine) (PEI) have been studied. The APTMS nano-hybrids showed batch capacities for copper equal to or better than the corresponding polymer-based micro-hybrids. Loading of the PEI on the nanoparticles was independent of molecular weight of the polymer. Dynamic light scattering measurements showed that the SiO 2 nanoparticles and the composites made from them aggregate in water and the degree of aggregation is dependent on the surface modification. All of the amine-modified materials were catalysts for the Knoevenagel reaction but interestingly, the microparticles modified with APTMS were better catalysts than the corresponding nanoparticles or the polyamine modified composites. Solid-state 19 Si NMR has been used to elucidate the surface structure of the various composites.

Glutaraldehyde‐crosslinking for improved copper absorption selectivity and chemical stability of polyethyleneimine coatings

“…To this end the nano‐thin coating material was self‐assembled onto mesoporous silica carriers in the form of diatomaceous earth particles to have a large surface area available for copper absorption. Such silica‐polyamine composite material could also be of interest for other applications, for example, catalysis …”