Fast responsive thermally stable silica microspheres for sensing evaluation: sol–gel approach

Abstract

Cetyltrimethylammonium bromide (CTAB) micelle-templated mesoporous SiO2 particles (MSPs) are synthesized by sol–gel method. The CTAB templated SiO2 particles (SPs) possessed spherical structure with low average surface roughness (Ra) 1 nm. The CTAB template is effectively removed from SPs by 400 °C heat treatment without any cracks and disruption of the bonding between the functional groups and the SiO2 surface. After CTAB template removal, SiO2 microspheres (SMSs) possessed high surface area 640 m2/g, pore radius 10 nm, and Ra ~ 4.4 nm, making them highly attractive for sensing. Thermal gravimetric analysis (TGA) confirmed that SMSs are thermally stable, showing 0.7% weight loss after 429 °C temperature. Phenol red immobilized SMSs show large pKa value 8.1 at 560 nm. Good repeatability, no leaching traces, and fast response time ~0.09 s in basic media suggested that proposed material has potential for opto-chemical sensing/photonic applications. [Figure not available: see fulltext.].