Surface-modification of silver nanoparticle–based polydimethylsiloxane composite for fabrication of strain sensor

Abstract

Composites consisting of surface-treated silver nanoparticles (AgNPs) in a polymer matrix were used to fabricate strain sensors. In order to ensure a good interaction of AgNPs with the polymer matrix in the composite, AgNPs were treated with 3-aminopropyltrimethoxysilane (APTMS). Silane-treated AgNPs (AM-AgNPs) contain, on their surface, an efficient coupling agent used in composites and as an adhesion promoter in adhesive formulation. The surface-treated conductive filler exhibits a good interaction with the PDMS matrix and improved composite performance, suggesting a good interface between AgNPs and the polymer matrix in the composite. AM-AgNPs were used as conductive filler in the composite, and an AM-AgNPs–based polydimethylsiloxane composite (AM-AgNPs@PDMS) strain sensor was fabricated via a drop-casting method. The surface morphology of the composite material and the electromechanical properties of the strain sensor were investigated. It was observed that both silane and amine groups were successfully grafted on the surface of the AgNPs, improving the dispersion and interfacial interaction in the PDMS matrix. The fabricated AM-AgNPs@PDMS composite strain sensor exhibited good electrical conductivity and sensing properties, measured as hysteresis behaviour until reaching 20% strain level; good sensitivity (Gauge Factor (GF) = 8.73 at 50% strain level); linearity (R2 = 0.9558); and good stability.