Optimization of conductive nanofillers in bio-based polyurethane foams for ammonia-sensing application

Abstract

This study focuses on transforming inherently insulating bio-based polyurethane foam into a susceptible gas sensor. The foam is chemically treated and reinforced with conductive fillers, including polyaniline, zinc oxide, and multi-walled carbon nanotubes, synthesized through in situ polymerization. A statistical approach employing the design of experiments with response surface methodology was applied for optimization. Scanning electron microscopy imaging visually confirmed the size, shape, and uniformity of nanofillers in the polyurethane foam. The electrical conductivity of the composite material and its sensitivity to ammonia exposure were evaluated using a Rigol DM3068 digital multi-meter. Our optimization identified the ideal composition to achieve the highest electrical conductivity, attained with 2.5 wt% polyaniline, 0.5 wt% zinc oxide, and 1 wt% multi-walled carbon nanotubes, resulting in a value of 2544.30 S/m. The resistance measurements demonstrated the sample's suitability for ammonia sensing, ranging from 0.8 to 200 Ω with a response time of less than 20 s. In conclusion, our research underscores the versatility of this innovative material, providing a comprehensive solution for gas detection across various domains. By sensitively responding to ammonia, this composite material safeguards the industrial environment and finds applications in healthcare and agriculture, contributing to enhanced safety, and diagnostics. Highlights: Fabricated bio-based polyurethane foam into a conductive gas sensor Used polyaniline, zinc oxide, and multi-walled carbon nanotube fillers synthesized via in situ polymerization Optimized using design of experiments with response surface methodology and analyzed with scanning electron microscopy Achieved excellent electrical conductivity Ammonia sensing with 0.8 to 200 Ω resistance for industrial, healthcare, and agricultural applications.