A Nonaqueous Redox-Matched Flow Battery with Charge Storage in Insoluble Polymer Beads**

We describe the nonaqueous redox-matched flow battery (RMFB), where charge is stored on redox-active moieties covalently tethered to non-circulating, insoluble polymer beads and charge is transferred between the electrodes and the beads via soluble mediators with redox potentials matched to the active moieties on the beads. The RMFB reported herein uses ferrocene and viologen derivatives bound to crosslinked polystyrene beads. Charge storage in the beads leads to a high (approximately 1.0–1.7 M) effective concentration of active material in the reservoirs while preventing crossover of that material. The relatively low concentration of soluble mediators (15 mM) eliminates the need for high-solubility molecules to create high energy density batteries. Nernstian redox exchange between the beads and redox-matched mediators was fast relative to the cycle time of the RMFB. This approach is generalizable to many different redox-active moieties via attachment to the versatile Merrifield resin.     

The isotropic and anisotropic EPR spectra of the tetrafluoroethylene radical anion

The tetrafluoroethylene radical anion has been generated in solid solutions by electron addition to the parent molecule. Both its isotropic and anisotropic EPR spectra have been observed, including the isotropic ¹³C satellite lines in natural abundance. The isotropic EPR parameters are a_F = 94.3 G, a_C = 48.7 G, and g = 2.0027. Two possible geometries, planar and chair, are discussed for this radical anion. The magnitude of the ¹⁹F and ¹³C hyperfine coupling constants are consistent with a planar (D_2h) structure provided that the unpaired electron occupies the 5b_1u (σ*) rather than the 2b_1g (π*) molecular orbital which is predicted by ab initio calculations to be the LUMO of the parent molecule. On the other hand, the EPR parameters do not rule out a chair (C_2h) structure if the bending of the CF₂ groups introduces only a small distortion from planarity.     

Correlations in stochastic theories of chemical reactions

A comprehensive study of correlations in linear and nonlinear chemical reactions is presented using coupled chemical and diffusion master equations. As a consequence of including correlations in linear reactions the approach to the steady-state Poisson distribution from an initial non-Poissonian distribution is given by a power law rather than the exponential predicted by neglecting correlations. In nonlinear reactions we show that a steadystate Poisson distribution is achieved in small volumes, whereas in large volumes a non-Poissonian distribution is built up via the correlation. The spatial correlation function is calculated for two examples, one which exhibits an instability, the other which exhibits a second-order phase transition, and correlation length and correlation time are calculated and shown to become infinite as the critical point is approached. The critical exponents are found to be classical.     

Toward one‐pot olefin/thiophene block copolymers using an in situ ligand exchange

Block copolymers containing both conducting and insulating segments are of interest due to their enhanced electrical properties arising from their increased crystallization. Yet few methods exist for generating these copolymers, because the reaction conditions for synthesizing each block are often incompatible. Herein, efforts toward identifying a one‐pot, living polymerization method for synthesizing block copolymers of 1‐pentene and 3‐hexylthiophene is described. An in situ ligand exchange enables the optimal catalyst to be utilized for synthesizing each block. Even under these conditions, however, only homopolymers are observed. Computational studies modeling the ligand exchange reveal that the added stabilizing ligands likely inhibit propagation of the second block. These results suggest an ancillary ligand‐based “goldilocks” effect wherein catalysts that are stable yet still reactive are required. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1601–1605     

Interlaboratory comparison of size and surface charge measurements on nanoparticles prior to biological impact assessment

The International Alliance for NanoEHS Harmonization (IANH) organises interlaboratory comparisons of methods used to study the potential biological impacts of nanomaterials. The aim of IANH is to identify and reduce or remove sources of variability and irreproducibility in existing protocols. Here, we present results of the first IANH round robin studies into methods to assess the size and surface charge of suspended nanoparticles. The test materials used (suspensions of gold, silica, polystyrene, and ceria nanoparticles, with [primary] particles sizes between 10?nm and 80?nm) were first analysed in repeatability conditions to assess the possible contribution of between-sample heterogeneity to the between-laboratory variability. Reproducibility of the selected methods was investigated in an interlaboratory comparison between ten different laboratories in the USA and Europe. Robust statistical analysis was used to evaluate within- and between-laboratory variability. It is shown that, if detailed shipping, measurement, and reporting protocols are followed, measurement of the hydrodynamic particle diameter of nanoparticles in predispersed monomodal suspensions using the dynamic light scattering method is reproducible. On the other hand, measurements of more polydisperse suspensions of nanoparticle aggregates or agglomerates were not reproducible between laboratories. Ultrasonication, which is commonly used to prepare dispersions before cell exposures, was observed to further increase variability. The variability of the zeta potential values, which were also measured, indicates the need to define better surface charge test protocols and to identify sources of variability.     

Explosives detection with electron‐rich polymers

The application of polymeric films as alarms for explosive materials is a critical issue these days as mandated by homeland security requirements. Amongst the multiple advantageous points of applying polymer films in this area is the fact that they are cheap material, so they can be applied on a broad scale for low cost. The basic idea of the current work is based on the fact that common explosives are electron deficient because of the existence of the nitro‐groups in their chemical structures, and this causes their high affinities towards electron rich materials to form charge‐transfer complex. Our endeavor is to trace any charge‐transfer complex formation, which would definitely cause a recognizable change in their physical properties. These changes in the polymers' physical properties could be utilized as alerts for the existence of explosive materials, especially if such changes could be incorporated into sophisticated electronic circuits that would give strong for traces of explosives. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of fullerene-based nanomaterial in serum matrix by CE

With the increasing interest in using nanoparticles as vehicles for drug delivery and image contrast agents, there is a need to develop assays for their detection and quantitation in complex matrices to facilitate monitoring their biodistribution. In this study, we developed a CE approach for the analysis of two nanoparticles: carboxyfullerene (C3) and dendrofullerene (DF1) in both standard solutions and a serum matrix. These highly soluble, charged C(60) derivatives were characterized by CZE using either a bare or dynamically coated fused-silica capillaries. The resolution of both nanoparticles was slightly lower with the coated capillary; however, their migration times were faster. While separation of the DF1 nanoparticles using MEKC resulted in a greater number of observable peaks, the peak profile of C3 was basically unchanged regardless of whether SDS micelles were added to the running buffers or not. The MEKC and/or CZE assays were then used to quantitate the C3 and DF1 nanoparticles in spiked human serum samples. The quantitation of the nanoparticles was linear from 0-500 microg/mL with detection limits ranging from 0.5 to 6 microg/mL.