Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization

Laser-scribed Graphene Electrodes Functionalized with Nafion/Fe3O4 Nanohybrids for the Ultrasensitive Detection of Neurotoxin Drug Clioquinol

The analysis of pharmaceutical active ingredients plays an important role in quality control and clinical trials because they have a significant physiological effect on the human body even at low concentrations. Herein, a flexible three-electrode system using laser-scribed graphene (LSG) technology, which consists of Nafion/Fe₃O₄ nanohybrids immobilized on LSG as the working electrode and LSG counter and reference electrodes on a single polyimide film, is presented. A Nafion/Fe₃O₄/LSG electrode is constructed by drop coating a solution of Nafion/Fe₃O₄, which is electrostatically self-assembled between positively charged Fe₃O₄ and negatively charged Nafion on the LSG electrode and is used for the first time to determine a neurotoxicity drug (clioquinol; CQL) in biological samples. Owing to their porous 3D structure, an enriched surface area at the active edges and polar groups (OH, COOH, and -SO₃H) in Nafion/Fe₃O₄/LSG electrodes resulted in excellent wettability to facilitate electrolyte diffusion, which gave ∼twofold enhancement in electrocatalytic activity over LSG electrodes. The experimental parameters affecting the analytical performance were investigated. The quantification of clioquinol on the Nafion/Fe₃O₄/LSG electrode surface was examined using differential pulse voltammetry and chronoamperometry techniques. The fabricated sensor displays preferable sensitivity (17.4 μA μM^-1 cm^-2), a wide linear range (1 nM to 100 μM), a very low detection limit (0.73 nM), and acceptable selectivity toward quantitative analysis of CQL. Furthermore, the reliability of the sensor was checked by CQL detection in spiked human blood serum and urine samples, and satisfactory recoveries were obtained.

Donnan Membrane Process for the Selective Recovery and Removal of Target Metal Ions-A Mini Review

Membrane-based water purification technologies contribute significantly to water settings, where it is imperative to use low-cost energy sources to make the process economically and technically competitive for large-scale applications. Donnan membrane processes (DMPs) are driven by a potential gradient across an ion exchange membrane and have an advantage over fouling in conventional pressure driven membrane technologies, which are gaining attention. DMP is a removal, recovery and recycling technology that is commonly used for separation, purification and the concentrating of metals in different water and waste streams. In this study, the principle and application of DMP for sustainable wastewater treatment and prospects of chemical remediation are reviewed and discussed. In addition, the separation of dissolved metal ions in wastewater settings without the use of pressure driven gradients or external energy supply membrane technologies is highlighted. Furthermore, DMP distinctive configurations and operational factors are explored and the prospects of integrating them into the wastewater treatment plants are recommended.

Effect of Elevated Temperatures on the States of Water and Their Correlation with the Proton Conductivity of Nafion

For the first time, we report the effects of elevated temperatures, from 80 to 100 °C, on the changes in the states of water and ion-water channels and their correlation with the proton conductivity of Nafion NR212, which was investigated using a Fourier transform infrared spectroscopy study. Experimentally, three types of water aggregates, protonated water (H+(H2O) n ), nonprotonated hydrogen (H)-bonded water (H2O···H2O), and non-H-bonded water, were found in Nafion, and the existence of those three types of water was confirmed through ab initio molecular dynamics simulation. We found that the proton conductivity of Nafion increased for up to 80 °C, but from 80 to 100 °C, the conductivity did not increase; rather, all of those elevated temperatures showed identical conductivity values. The proton conductivities at lower relative humidities (RHs) (up to 50%) remained nearly identical for all elevated temperatures (80, 90, and 100 °C); however, from 60% RH (over λ = 4), the conductivity remarkably jumped for all elevated temperatures. The results indicated that the amount of randomly arranged water gradually increased and created more H-bonded water networks in Nafion at above 60% RH. From the deconvolution of the O-H bending band, it was found that the volume fraction f i (i=each deconvoluted band) of H-bonded water for elevated temperatures (>80-100 °C) increased remarkably higher than for 60 °C.

Redox-Responsive Viologen-Mediated Self-Assembly of CB[7]-Modified Patchy Particles

Sulfonated surface patches of poly(styrene)-based colloidal particles (CPs) were functionalized with cucurbit[7]uril (CB[7]). The macrocycles served as recognition units for diphenyl viologen (DPV(2+)), a rigid bridging ligand. The addition of DPV(2+) to aqueous suspensions of the particles triggered the self-assembly of short linear and branched chainlike structures. The self-assembly mechanism is based on hydrophobic/ion-charge interactions that are established between DPV(2+) and surface-adsorbed CB[7]. DPV(2+) guides the self-assembly of the CPs by forming a ternary DPV(2+)⊂(CB[7])2 complex in which the two CB[7] macrocycles are attached to two different particles. Viologen-driven particle assembly was found to be both directional and reversible. Whereas sodium chloride triggers irreversible particle disassembly, the one-electron reduction of DPV(2+) with sodium dithionite causes disassembly that can be reversed via air oxidation. Thus, this bottom-up synthetic supramolecular approach allowed for the reversible formation and directional alignment of a 2D colloidal material.

Architecture, Assembly, and Emerging Applications of Branched Functional Polyelectrolytes and Poly(ionic liquid)s

Branched polyelectrolytes with cylindrical brush, dendritic, hyperbranched, grafted, and star architectures bearing ionizable functional groups possess complex and unique assembly behavior in solution at surfaces and interfaces as compared to their linear counterparts. This review summarizes the recent developments in the introduction of various architectures and understanding of the assembly behavior of branched polyelectrolytes with a focus on functional polyelectrolytes and poly(ionic liquid)s with responsive properties. The branched polyelectrolytes and poly(ionic liquid)s interact electrostatically with small molecules, linear polyelectrolytes, or other branched polyelectrolytes to form assemblies of hybrid nanoparticles, multilayer thin films, responsive microcapsules, and ion-conductive membranes. The branched structures lead to unconventional assemblies and complex hierarchical structures with responsive properties as summarized in this review. Finally, we discuss prospectives for emerging applications of branched polyelectrolytes and poly(ionic liquid)s for energy harvesting and storage, controlled delivery, chemical microreactors, adaptive surfaces, and ion-exchange membranes.