The aim of this study was to evaluate the effect of replacing corn starch by whey protein isolated (WPI) in biodegradable polymer blends developed by extrusion. X-ray diffraction showed the presence of a Vh-type crystalline arrangement. The films were homogeneous, indicating strong interfacial adhesion between the protein and the thermoplastic starch matrix (TPS) as observed in scanning electron microscopy. The addition of WPI on TPS matrix promoted an increase in the thermal stability of the materials. It was observed 58.5% decrease in the water vapor permeability. The effect of corn starch substitution by WPI on mechanical properties resulted in a more resistant and less flexible film when compared the TPS film. The addition of WPI caused greenish yellow color and less transparent films. The substitution of corn starch by WPI made it possible to obtain polymer blends with improved properties and represents an innovation for application as a packaging material.

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A resistance detection device for dissolved molecular oxygen in aqueous solutions is prepared using a chemiresistor material as sensor platform. The chemiresistive circuit element is fashioned from a thin film of a cobalt-salen metallopolymer electrodeposited on a platinum electrode. Electrochemical impedance spectroscopy shows that the resistive and capacitive properties of the sensor platform depend on the presence of dissolved oxygen. The electrical circuit models are R(Q/R)(Q/R) and R(Q/R)(Q/RW) in the absence and presence of oxygen, respectively. The chemiresistor sensor exhibits good sensitivity (0.483 kΩ L mg), excellent reversibility and excellent linearity over a range of dissolved oxygen concentrations typically found under environmental conditions (2.72-40.9 mg L). The sensor fabricated in this work can potentially serve as an alternative sensor for the detection of dissolved oxygen in environmental samples.

The present paper describes the electrochemical activity of a Ni(II)‐Schiff base metallopolymer electrode for the oxidation of ethanol in alkaline media. The scanning electron microscope results show that the metallopolymer at the glassy carbon surface has a nanoflake‐like lamellar structure, and there is no molecular structural change after treatment with NaOH. Voltammetry measurements indicate that the metallopolymer acts as efficient material for the electrocatalytic oxidation of ethanol, where a high‐valent nickel(IV) was revealed as the reactive intermediate during the anodic scan. An isopotential point can be observed in rotating disk electrode voltammetry for ethanol oxidation. The electrode surface may be considered to consist of two independent electrochemical regions, one corresponding to the ethanol electro‐oxidation by nickel(IV) and the second corresponding to water oxidation. The Tafel slopes were found to be 246 mV dec−1 at low overpotentials and 44 mV dec−1 at high overpotentials, which suggest that the first electron transfer step is the rate controlling step. The specific activity of the metallopolymer‐modified electrode for the ethanol electro‐oxidation reaction was 6.66 mA cm−2 for 0.130 μmol cm−2 of electroactive species of metallopolymer at 0.6 V vs. SCE.