Overoxidation of Intrinsically Conducting Polymers

Intrinsically conducting polymers may undergo significant changes of molecular structure and material properties when exposed to highly oxidizing conditions or very positive electrode potentials, commonly called overoxidation. The type and extent of the changes depend on the experimental conditions and chemical environment. They may proceed already at much lower rates at lower electrode potentials because some of the processes associated with overoxidation are closely related to more or less reversible redox processes employed in electrochemical energy conversion and electrochromism. These changes may be welcome for some applications of these polymers in sensors, extraction, and surface functionalization, but in many cases, the change of properties affects the performance of the material negatively, contributing to material and device degradation. This report presents published examples, experimental observations, and their interpretations in terms of both structural and of material property changes. Options to limit and suppress overoxidation are presented, and useful applications are described extensively.

Voltammetric Sensors Based on Various Nanomaterials for the Determination of Sulfonamides

Background:

The widespread applications of sulphonamides, as antibacterial or antimicrobial agents, and their mechanism of actions in the body, have changed their determination to an important issue in the area of human health.

Objective:

Here, history of developing voltammetric sensors based on nanomaterials for the detection of sulfonamides including sulfadiazine, sulfamethoxazole, sulfacetamide, sulfadimethoxine, sulfathiazole, sulfamethiazole and sulfamerazine is reviewed. Modified electrodes based on various nanomaterials (carbonaceous nanomaterials, Metallic Nanoparticles (MNPs), conducting nanopolymers) have been reported, and studies showed that nanomaterials have been mostly used to overcome problems like the poor sensitivity and selectivity of bare electrodes. The study covers the properties of each sensor in detail, and reports and compares the linear ranges, Limits of Detection (LODs), reproducibility, and reusability of the electrodes reported so far.

Novel Thermosensitive Core⁻Shell Surface Molecularly Imprinted Polymers Based on SiO₂ for the Selective Adsorption of Sulfamethazine

In this research, a novel, sulfamethazine, thermosensitive, molecularly-imprinted polymer (MIP) with an obvious core–shell structure for the enrichment of sulfamethazine (SMZ), which involved temperature sensitive monomer N-Isopropylacrylamide, functional monomer methacrylic acid and cross-linking agents ethyleneglycol dimethacrylate (EGDMA) and N,N′-methylenebisacrylamide, was successfully compounded using the surface polymerization method. To ensure the best experimental group, we designed and compared three groups of controlled experiments of MIPs with different crosslinking agents. When the adsorption temperature was almost the lower critical solution temperature (LCST) of Poly(N-Isopropylacrylamide), the preparative MIPs showed outstanding adsorption capacity and specific identification to sulfamethazine. Moreover, this allowed the MIPs to better facilitate by combining the template molecules, as well as optimizing the imprinting factor. In addition, after 80 min, the adsorption of the MIPs leveled off and remained constant, and the adsorption quantity reached (a maximum of) at 8.1 mg·g⁻¹.