Silica nanowires obtained on clay mineral layers and their influence on mini-emulsion polymerisation

Abstract

The increased interest in silica nanowires for nanophotonics, mechanical applications, microsurgery, chemical and biological sensors strongly motivates the search for new discoveries involving complex silica nanowire-clay mineral layers (SiNW), particularly focusing on their growth mechanism, their involvement during polymer synthesis and the generation of a new class of polymer nanocomposites. This paper addresses the major findings involving the growth mechanism of silica nanowires on the clay mineral layers as well as their high segmental mobility and influence on the kinetics of butylacrylate mini-emulsion radical polymerisation. The growth mechanism for the silica nanowires was a sol-gel process involving tetraethylorthosilicate at the edge groups of the clay layers after blocking the reactive sites with a monofunctional alkoxysilane. To demonstrate the mobility of the network, an indirect method was utilised, specifically the interaction between the ethoxylated molecules and Tween 60. No cross-linking side effects occurred in the silica nanowires. SiNW enhance the free radical polymerisation of butylacrylate in dispersed media, increasing the monomer conversion from 2.5% to 33%. The kinetics of the polymerisation process can be tuned by SiNW, modulating the system between emulsion- and mini-emulsion-like systems by acting on the pseudo-steady state interval of the radicals (10%–40% conversion).