Humidity Sensing Performance of <I>In-Situ</I> Fabricated Cu/Cu<SUB>2</SUB>O/Cu<SUB>2</SUB>S-Polymer Nanocomposite via Polyphenylene Sulphide Cyclisation Route

Abstract

We herein report the feasibility of novel polymer-inorganic solid state reaction route for simultaneous in situ generation of Cu2S and Cu nanostructures in polymer network. Polyphenylene Sulphide (PPS) which is engineering thermoplastic acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the two reactants i.e., copper acetate and PPS by varying molar ratios mainly 1:1, 1:5, 1:10, 1:15, 1:20 at the crystalline melting temperature (285 degrees C) of PPS. The synthesized products were characterized using various physicochemical characterization techniques like X-ray Diffractometry, Field emission Scanning Electron Microscopy, Transmission Electron Microscopy, UV-Visible spectroscopy and X-ray photoelectron spectroscopy. The prima facie observations suggest occurrence of nanocrystalline Cu2S in case of product obtained with equimolar ratio, whereas remaining samples show mixture of Cu and Cu2O. The TEM analysis reveals nanoscale polydispersity (5-60 nm) and prevalence of mainly spherical morphological features in all the cases with occasional indications of plate like and cubical morphological features depending upon the molar ratio of the reactants. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 70% RH) was compared for these nanocomposites. The linear response is obtained for all the samples. The sensitivity of 1:1 molar ratio sample was found to be maximum among all the samples.

Chemical and biological sensing with nanocomposites prepared from nanostructured copper sulfides

“…Different from PVA, PPS is the sulfide source per se reacting with copper acetate to form Cu2S at the melting temperature (285 °C) of PPS. [41] The Cu2S nanocrystals have polydispersity of 5 -60 nm that is only obtained with equimolar ratio of PPS and copper acetate.…”

“…The gelatin in the composite contains polar amino acids on the polypeptide chain that form hydrogen bonds with the ethanol molecules. Using a hydrophilic polymer such as polyphenylene sulfide (PPS) and polyvinylalcohol (PVA) in the nanocomposites with CuS nanoparticles (table 1) extends the applications of Cu x S to humidity sensing [40,41]. Like ethanol monitoring, humidity sensors are important in industrial processing (semiconductor manufacturing, home and automobile appliances) and environmental controls (agriculture, food and storage) [66].…”

“…The percolation thresholds of the nanocomposites are observed to be in the concentration range between 16 and 22 wt%, accompanied by a conductivity change from 10 -9 to 10 -2 Ω cm −1 . As opposed to PVA, PPS is the sulfide source per se that reacts with copper acetate to form Cu 2 S at the melting temperature (285 • C) of PPS [41]. Cu 2 S nanocrystals have a polydispersity of 5-60 nm that is only obtained with an equimolar ratio of PPS and copper acetate.…”

“…Using the hydrophilic polymer such as polyphenylene sulfide (PPS) and polyvinylalcohol (PVA) in the nanocomposites with the CuS nanoparticles (Table 1), extends the applications of CuxS to humidity sensing. [40,41] Like ethanol monitoring, the humidity sensors are important in industrial processing (semiconductor manufacturing, home and automobile appliances) and environmental control (agriculture, food and storage). [66] Response of both nanocomposites upon exposure of water vapors caused by decrease in electrical conductivity of the sensors which is attributed to the change of permittivity of the nanocomposite.…”