Development of Macroporous co-Polyesters of Glyceryl Methacrylate with Acrylonitrile and Styrene for Electrical Sensing of Ammonia Vapor

This paper reports the development of highly efficient and selective electrical sensors of ammonia and methylamine vapor from conducting co -polyesters glyceryl methacrylate- co -acrylonitrile (PGMA-AN) and glyceryl methacrylate- co -styrene (PGMA-S). The cross-linked co -polyesters are prepared via very simple synthetic pathways that involve thermal polymerization techniques. Scanning electron micrographs clearly shows the macropores of the gels with pore size ranging about 2–6 μm. Complete electrical studies including impedance, dielectric, ac conductivity, current–voltage and transport number measurements were carried out and showed significant results. Alternating current conductivity values at 30 °C for PGMA-AN and PGMA-S are 8.10 × 10 –6 and 4.3 × 10 –6 S·cm –1 respectively. The PGMA-AN and PGMA-S gels retain around 68.42% and 62.95% ionic conduction. Ammonia sensitivity was monitored with the help of change in impedance with time and current–voltage measurements. PGMA-AN and PGMA-S show 2 and 1.7 order of magnitude decreases in their impedance values when exposed to ammonia vapor for 5 min. PGMA-AN and PGMA-S showed a maximum of 99.5% and 98.3% increase in current density in the presence of ammonia upon application of an external bias. The limits of detection of ammonia for PGMA-AN and PGMA-S are 13.9 and 16 ppm, respectively.