Molecularly imprinted polymer nanomaterials and nanocomposites by controlled/living radical polymerization

Since the pioneering work of Wulff and Mosbach more than 30 years ago, molecular imprinting of synthetic polymers has emerged as a robust and convenient way for synthesizing polymeric receptor materials bearing specific recognition sites for target molecules. The resulting materials, molecularly imprinted polymers (MIPs), are therefore commonly referred to as ‘plastic antibodies’. They are obtained by polymerizing a scaffold around a target, or a derivate thereof, which acts as a molecular template. MIPs have been successfully applied in many areas including affinity separation, immunoassays, chemical sensing, solid-phase extraction, drug delivery, cell and tissue imaging, direct synthesis and catalysis. In terms of affinity and selectivity, MIPs are on a par with biological receptors like antibodies, and this is accompanied by a superior chemical and physical stability, compatibility with organic media, reusability, easy engineering and low cost. These advantages represent the main reasons for the wide interest raised around molecularly imprinted materials. Mainly produced by free radical polymerization (FRP) of vinyl monomers, MIPs have also taken advantage of the introduction of controlled/living radical polymerization (CRP) techniques, which have literally transformed polymer chemistry over the last decade. This review describes the advantages arising from the use of CRP in synthesizing MIPs, both in terms of sheer binding properties as well as for their remarkable potential for post-polymerization functionalization, for the synthesis of MIP nanomaterials and for the integration of MIPs into composites and hybrid materials. The benefits of using CRP are critically assessed with respect to the still largely applied FRP and guidelines are provided for choosing the most convenient technique to fit a specific targeted application of MIPs.     

Corrosion-free electrochemical synthesis of polyaniline using Cu counter electrode in acidic medium

Polyaniline (PAni) was electrochemically synthesized from aniline sulfate (AS) in the presence and in absence of H₂SO₄ using Cu counter electrode. No significant corrosion of the Cu electrode was found while synthesizing from AS in presence of H₂SO₄, whereas relatively higher corrosion of Cu as well as contamination of synthesized PAni with corroded Cu were observed for the synthesis from aniline in presence of H₂SO₄ or from AS in the absence of H₂SO₄. Corrosion-free synthesis yields PAni free from contamination of Cu and exhibits smaller particle size and superior electrical and supercapacitive behavior compared to the process exhibiting corrosion of counter electrode.     

Non-aqueous rechargeable Al–O2 battery with a bifunctional catalyst of carbon microspheres

Non-aqueous secondary Al-O₂ batteries have recently received much attention due to their high theoretical capacity, element richness, safety and low cost, although there are still many problems to be overcome. In this paper, a type of Al-O₂ battery using AlCl₃/[EMIm]Cl ionic liquid as electrolyte and carbon microspheres (CMs) as air electrode was considered. The batteries with CMs deliver a high specific capacity of 820 mAh g^?1 in the first cycle at the current density of 25 mA g^?1 and a low charge voltage. In addition, CMs show better redox catalytic activity for O₂ compared with super-p (SP) and the Al-O₂ batteries have two obvious oxygen reduction processes corresponding to two reductive peaks.     

Detection of a Specific Biomarker for Epstein-Barr Virus Using a Polymer-Based Genosensor

This paper describes methodology for direct and indirect detections of a specific oligonucleotide for Epstein-Barr virus (EBV) using electrochemical techniques. The sequence of oligonucleotide probe (EBV1) revealed a high sequence identity (100%) with the EBV genome. For the development of the genosensor, EBV1 was grafted to the platform sensitized with poly(4-aminothiophenol). After that, the hybridization reaction was carried out with the complementary target (EBV2) on the modified electrode surface using ethidium bromide as DNA intercalator. The oxidation peak currents of ethidium bromide increased linearly with the values of the concentration of the complementary sequences in the range from 3.78 to 756 μmol·L⁻¹. In nonstringent experimental conditions, this genosensor can detect 17.32 nmol·L⁻¹ (three independent experiments) of oligonucleotide target, discriminating between complementary and non-complementary oligonucleotides, as well as differentiating one-base mismatch, as required for detection of genetic diseases caused by point mutations. The biosensor also displayed high specificity to the EBV target with elimination of interference from mix (alanine, glucose, uric acid, ascorbic acid, bovine serum albumin (BSA), glutamate and glycine) and good stability (120 days). In addition, it was possible to observe differences between hybridized and non-hybridized surfaces through atomic force microscopy.     

Supercritical carbon dioxide extraction of lithium-ion battery electrolytes

Two different separator materials (polyethylene fleece – Freudenberg 2190 and porous glass fiber – Whatman^® GF/D) and two different lithium-ion battery electrolytes have been investigated regarding their behavior in an autoclave extraction with supercritical helium head pressure carbon dioxide (sc HHPCO₂). Mixtures of dimethyl carbonate (DMC)/ethylene carbonate (EC) and ethylmethyl carbonate (EMC)/EC, each with 1 mol/L LiPF₆ were used.In addition to these proof of principle experiments, the developed extraction method was further applied to real battery samples. Commercial 18650 cells (after formation and aging) were opened and the jelly roll was extracted with sc HHPCO₂. Extracts were analyzed with gas and ion chromatography (GC, IC). Recovery rates and extract compositions strongly depend on the material of which the electrolyte is extracted. Further structure determination of electrolyte aging products was performed with different ionization modes in GC–mass spectrometry (GC–MS) experiments. Diethyl carbonate (DEC), dimethyl-2,5-dioxahexane dicarboxylate (DMDOHC), ethylmethyl-2,5-dioxahexane dicarboxylate (EMDOHC) and diethyl-2,5-dioxahexane dicarboxylate (DEDOHC) are aging products of electrolyte degradation which were successfully extracted and identified. Their concentrations correlate with solid electrolyte interphase (SEI) growth on the negative electrode which was investigated with scanning electron microscopy (SEM).     

Analysis and design of smart mandrels using shape memory polymers

Based on the thermomechanical mechanism of shape memory polymers (SMPs), the three-dimensional thermomechanical constitutive equation that can be used in the ABAQUS finite element simulation was derived. Then this paper compiled UMAT subroutine and simulated the thermomechanical behaviors of SMP smart mandrels. In addition, the properties of shape fixity and shape recovery ratio of SMP were considered in detail. Finally, filament winding experiments were proceeded on bottle-shaped and air duct-shaped mandrels and the simple and efficient demoulding of SMP mandrels were verified. The results showed the feasibility of SMP as the smart mandrels from practical application in the future.     

Performance optimization of polymer electrolyte membrane fuel cells using the Nelder-Mead algorithm

The direct-search simplex method for function optimization has been adapted to performance optimization of polymer electrolyte membrane fuel cells (PEMFCs). The established method is strongly application oriented and uses only experimentally determined data for optimization. It is not restricted to discrete parameters optimums and does not require the use of third-party software or computational resources. Hence, it is easy to implement in fuel cell testing stations. The optimization consists of finding, for a given fuel cell load, an optimum set of values of the 7 fuel cell operating parameters: the fuel cell temperature, the reactants' stoichiometric ratios, the reactants' inlet relative humidity, and the reactants' outlet pressures, resulting in the highest fuel cell performance. The performance is measured using a scalar function of the operating parameters and the load and can be defined according to needs.Two PEMFC performance functions: the fuel cell voltage and the system-related fuel cell efficiency were optimized using the procedure for practically sized PEMFC stacks of two designs. With respect to the nominal operating conditions defined as optimal for each stack design by its manufacturer, the gains from the optimization procedure were up to over 12% and up to over 7% for the stack voltage and efficiency, respectively. The validation of the procedure involved 5 stack specimens and four laboratories and consistent results were obtained.