Polyaniline Langmuir-Blodgett film modified glassy carbon electrode as a voltammetric sensor for determination of Ag ions

A highly sensitive electrochemical sensor made of a glassy carbon electrode (GCE) coated with a Langmuir-Blodgett film (LB) containing polyaniline (PAn) doped with p-toluenesulfonic acid (PTSA) (LB/PAn-PTSA/GCE) has been used for the detection of trace concentrations of Ag⁺. UV-vis absorption spectra indicated that the PAn was doped by PTSA. The surface morphology of the PAn LB film was characterized by atomic force microscopy (AFM). The electrochemical properties of this LB/PAn-PTSA/GCE were studied using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The LB/PAn-PTSA/GCE was used as a voltammetric sensor for determination of trace Ag⁺ at pH 5.0 using linear scanning stripping voltammetry. Under the optimal experimental conditions, the stripping current was proportional to the Ag⁺ concentration over the range from 6.0 × 10⁻¹⁰ mol L⁻¹ to 1.0 × 10⁻⁶ mol L⁻¹, with a detection limit of 4.0 × 10⁻¹⁰ mol L⁻¹. The high sensitivity, selectivity, and stability of this LB/PAn-PTSA/GCE also demonstrated its practical utility for simple, rapid and economical determination of Ag⁺ in water samples.     

Fe3O4/poly(acrylic acid) hybrid nanoparticles for water‐based drilling fluids

Because of the sizes of the pore throat are on the nanometer scale, nanoparticles with sizes on the nanoscale have been developed as candidates for plugging materials during drilling in shale formation. In this study, Fe₃O₄ nanoparticles were prepared by a coprecipitation method, and then, Fe₃O₄/poly(acrylic acid) (PAA) hybrid nanoparticles were obtained through the modification of the Fe₃O₄ nanoparticles with PAA. The hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The magnetic properties, salt tolerance, and compatibility with sulfomethylated phenolic resin of the nanoparticles were studied. The plugging properties of the Fe₃O₄/PAA hybrid nanoparticles were evaluated by filtration testing of the filter cakes at ambient temperature and 80 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43967.     

Microwave-assisted polymer synthesis (MAPS) as a tool in biomaterials science: How new and how powerful

Lack of reproducibility, difficult and expensive scale-up and standarization of synthetic processes are the main hurdles towards the industrial production of raw synthetic and semi-synthetic polymers for (bio)pharmaceutical applications. Time- and energy-consuming synthetic pathways that usually involve the use of volatile, flammable or toxic organic solvents are apparently cost-viable and environment-friendly for the synthesis at a laboratory scale. However, they are often not viable in industrial settings especially due to the impact they have on the product cost and the deleterious effect on the environment. This has presented hurdles to the incorporation of many new biomaterials displaying novel structural features into clinics. Nevertheless, owing to unique advantages such as shorter reaction times, higher yields, limited generation of by-products and relatively easy scale-up without detrimental effects, microwave-assisted organic synthesis has become an appealing synthetic tool. Regardless of these features, the use of microwave radiation in biomaterials science has been comparatively scarce. A growing interest in the basic aspects of the synthesis of either ceramic and polymeric biomaterials has been apparent during the last decade. This article reviews the most recent and prominent applications of MW as a versatile tool to synthesize and process organic and inorganic polymeric biomaterials, and discusses the unmet goals and the perspectives for a technology that probably has the potential to make biomaterials more accessible pharmaceutical excipients and the products that involve them more affordable to patients.     

Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges

Proton-exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for efficient power generation in the 21st century. Currently, high temperature proton exchange membrane fuel cells (HT-PEMFC) offer several advantages, such as high proton conductivity, low permeability to fuel, low electro-osmotic drag coefficient, good chemical/thermal stability, good mechanical properties and low cost. Owing to the aforementioned features, high temperature proton exchange membrane fuel cells have been utilized more widely compared to low temperature proton exchange membrane fuel cells, which contain certain limitations, such as carbon monoxide poisoning, heat management, water leaching, etc. This review examines the inspiration for HT-PEMFC development, the technological constraints, and recent advances. Various classes of polymers, such as sulfonated hydrocarbon polymers, acid-base polymers and blend polymers, have been analyzed to fulfill the key requirements of high temperature operation of proton exchange membrane fuel cells (PEMFC). The effect of inorganic additives on the performance of HT-PEMFC has been scrutinized. A detailed discussion of the synthesis of polymer, membrane fabrication and physicochemical characterizations is provided. The proton conductivity and cell performance of the polymeric membranes can be improved by high temperature treatment. The mechanical and water retention properties have shown significant improvement., However, there is scope for further research from the perspective of achieving improvements in certain areas, such as optimizing the thermal and chemical stability of the polymer, acid management, and the integral interface between the electrode and membrane.     

Organic-inorganic nanocomposite polymer electrolyte membranes for fuel cell applications

Organic-inorganic nanocomposite polymer electrolyte membrane (PEM) contains nano-sized inorganic building blocks in organic polymer by molecular level of hybridization. This architecture has opened the possibility to combine in a single solid both the attractive properties of a mechanically and thermally stable inorganic backbone and the specific chemical reactivity, dielectric, ductility, flexibility, and processability of the organic polymer. The state-of-the-art of polymer electrolyte membrane fuel cell technology is based on perfluoro sulfonic acid membranes, which have some key issues and shortcomings such as: water management, CO poisoning, hydrogen reformate and fuel crossover. Organic-inorganic nanocomposite PEM show excellent potential for solving these problems and have attracted a lot of attention during the last ten years. Disparate characteristics (e.g., solubility and thermal stability) of the two components, provide potential barriers towards convenient membrane preparation strategies, but recent research demonstrates relatively simple processes for developing highly efficient nanocomposite PEMs. Objectives for the development of organic-inorganic nanocomposite PEM reported in the literature include several modifications: (1) improving the self-humidification of the membrane; (2) reducing the electro-osmotic drag and fuel crossover; (3) improving the mechanical and thermal strengths without deteriorating proton conductivity; (4) enhancing the proton conductivity by introducing solid inorganic proton conductors; and (5) achieving slow drying PEMs with high water retention capability. Research carried out during the last decade on this topic can be divided into four categories: (i) doping inorganic proton conductors in PEMs; (ii) nanocomposites by sol-gel method; (iii) covalently bonded inorganic segments with organic polymer chains; and (iv) acid-base PEM nanocomposites. The purpose here is to summarize the state-of-the-art in the development of organic-inorganic nanocomposite PEMs for fuel cell applications.     

Modifications of carbon for polymer composites and nanocomposites

The various forms of carbon used in composite preparation include mainly carbon-black, carbon nanotubes and nanofibers, graphite and fullerenes. This review presents a detailed literature survey on the various modifications of the carbon nanostructures for nanocomposite preparation focusing upon the works published in the last decade. The modifications of each form of carbon are considered, with a compilation of structure-property relationships of carbon-based polymer nanocomposites. Modifications in both bulk and surface modifications have been reviewed, with comparison of their mechanical, thermal, electrical and barrier properties. A synopsis of the applications of these advanced materials is presented, pointing out gaps to motivate potential research in this field.