A novel approach to the synthesis of SiO2–PVAc nanocomposites using a one-pot synthesis in supercritical CO2

Abstract

Inorganic–polymer nanocomposites are of significant interest for emerging materials due to their improved properties and unique combination of properties. A novel one-step synthesis route has been developed for making the polymer nanocomposites silica–poly(vinyl acetate) (SiO₂–PVAc) in supercritical CO₂ (scCO₂), wherein all raw chemicals, tetraethoxysilane (TEOS)/tetramethoxysilane (TMOS), vinyltrimethoxysilane (VTMO), vinyl acetate, initiator, and hydrolysis agent were introduced into one autoclave. In-situ ATR-FT-IR was applied to monitor the process in scCO₂, and the parallel reactions of free radical polymerization, hydrolysis/condensation, and linkage to the polymer matrix, were found to take place. The nanocomposites were also studied by transmission electron microscopy (TEM) and EDX element Si-mapping. Well-dispersed nanoparticles of 10–50 nm were formed. This process provides a significant improvement by providing a one-step synthesis route where the potentially recyclable scCO₂ works as a solvent, a modification agent, and a drying agent. This green process has potentially many advantages in producing new and unique materials, along with waste-reduction and energy-saving properties. Production of metal-oxide–polymer nanocomposites from non-inhalable liquid precursors also has significant potential for non-toxicity in biomedical and other fields.