DOI: https://doi.org/10.55373/mjchem.v28i2.306

Keywords: Polyaniline, silica, nanocomposites, ultrasonication, electrical conductivity, humidity sensing

Abstract

Polyaniline–silica (PANI–SiO₂) nanocomposites were synthesized via in-situ oxidative polymerization assisted by ultrasonication to enhance filler dispersion and interfacial bonding. Different SiO₂ loadings (8 wt%, 18 wt%, and 28 wt%) and ultrasonication times were investigated to optimize conductivity and morphology. Structural analysis by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed semi-crystalline ordering and strong interfacial interactions between PANI chains and SiO₂ nanoparticles. Field Emission Scanning Electron Microscopy (FESEM) and dynamic light scattering (DLS) revealed improved but heterogeneous dispersion of SiO₂ domains within the polymer matrix. Electrical conductivity and humidity sensing performance were optimal at 8 wt% SiO₂, while higher filler content led to reduced conductivity due to agglomeration. Humidity sensing tests demonstrated excellent sensitivity (>99.8%) across a wide relative humidity (11–93%), with stable and pronounced resistance responses attributed to hydrophilic Si–OH groups and enhanced proton hopping within the nanocomposite network. Compared with many reported conventional oxide-based sensors in the literature, the PANI–SiO₂ system offers potential advantages such as room-temperature operability and mechanical flexibility. These findings highlight the potential of ultrasonication-assisted PANI–SiO₂ nanocomposites for low-cost, high-performance humidity sensors in environmental monitoring and wearable applications.