Room Temperature Acid Catalysed Silanisation of Silica Nanoparticles in Non‐Polar Organic Solvents

Silanisation is a straightforward and effective surface modification commonly used to change surface chemistry of metal oxide materials. However, traditional silanisation methods in non‐polar solvents exhibit drawbacks such as the extensive use of modifying silanes and long reaction times for effective grafting as well elevated energy consumption resulting from refluxing. Herein, we explore liquid acids to catalyse silanisation at room temperature within a short reaction time of 1 h, utilising hydrophobic silanes with alkyl chains of lengths 3, 8 and 18. The adsorption of acid molecules onto the silica nanoparticle (SNP) surfaces was thoroughly examined through XPS. Additionally, the grafting density was quantified by analysing weight losses via TGA. XPS results revealed an insignificant amount of acid molecules adsorbed on the particles’ surface. Remarkably high grafting densities, of up to 2.79 chains/nm ² , were achieved with a silane utilisation of 0.93 mmol/g(silica). A comparative LCA study showed that the novel method reduced the GWP (kgCO ₂ eq/kg) of the silanisation step by 78%–92%, translating into 28%–48% GWP reduction for the overall process. The findings highlight that the use of acid catalysts provide best alternative silanisation process which is highly efficient and less energy intensive.