Combination of polymeric substrates and metal–polymer nanocomposites for optical humidity sensors

Abstract

This paper reports a combination of self-supported, 80-μm-thick polymeric substrates of poly(dimethyl siloxane), poly(methyl methacrylate), poly(vinyl alcohol) (PVA), and poly(N-vinylpyridine) (PVP) and nanocomposites, silver nanoparticle (nAg)/ 0.1% PVP (S1) and nAg/0.1% PVA (S2), for use in optical-transmission-type humidity sensors. Composites are synthesized by a chemical reduction method at optimum conditions, giving particle sizes of 5-10 nm and 10-20 nm, respectively, for nAg/0.1% PVP and nAg/ 0.1% PVA. Composite formation is confirmed using Fourier transform infrared spectroscopy (FTIR). The role of polymers in obtaining a smaller Ag particle size is studied using ultraviolet-visible spectroscopy and transmission electron microscopy. The nanocomposite is coated onto substrates either on a single side or on both sides by dip coating. The humidity response of nAg/0.1% PVP-0.1% PVP-nAg/0.1% PVP (S1-PVP-S1) sensors, measured using the direct optical transmission method, exhibits an enhancement in sensitivity [0.88 AE 0.04 (/% RH)] for the humidity range 6-94% RH and response (6 s) and recovery (8 s) times compared to nAg/0.1% PVP-PVP S1-PVP sensors and a linear response (R 2 ≥ 0.99). An attempt is made to explain the sensing process with the help of FTIR spectra in dry and humid environments.

Metal–Organic Framework-Based Composite for Photocatalytic Detection of Prevalent Pollutant

“…Lastly, the peaks at 1276 and 1229 cm –1 previously associated with the C–O bond were shifted to higher wavelengths, while the peak at 846 cm –1 assigned to the HC bonds was split into two sharp entities. Such peak position shifts were presumably due to the exposure of FDCA to Ag, in agreement with previous study showing peaks shifts in the FTIR spectra of polymers doped with Ag nanoparticles, as resulted from the coordination interaction between such nanoparticles and CO group or N atom in the aromatic ring of the polymer …”

Review of Optical Humidity Sensors

“…Poonam D. Mahapure et al [ 142 ] studied transmission-type humidity sensors using poly(dimethyl siloxane), poly(methyl methacrylate), PVA, and poly(N-vinylpyridine) (PVP) as substrates, and silver nanoparticle (nAg)/0.1% PVP (S1) and nAg/0.1% PVA (S2) as the sensing elements. A range of sensitivities from 0.84 to 0.92(/%RH) between 6%RH and 94%RH was reported.…”

Amphiphilic Poly(vinyl Alcohol) Copolymers Designed for Optical Sensor Applications—Synthesis and Properties

“…Polyaniline/poly(vinyl alcohol) composites [15] and silver-polyaniline/polyvinyl alcohol composites [16] were used as sensitive media for acoustic 2 of 11 wave-impedance humidity sensors and resistive humidity sensors, respectively. Thick PVA substrates (around 80 microns) doped with silver nanoparticles were applied for humidity sensing through transmittance measurements [17].…”