Photopolymerization of coordinated ionic liquid monomers: Realizing the benefits of structured media using only common reagents

Here, we provide a detailed report on a new type of structured media for improving photopolymerizations: coordinated ionic liquids (ILs). Coordinated ILs are readily formed from the bistriflimide ([Tf₂N]^?) anion and coordination complexes composed of Li⁺ cations with polar organic monomers without an additional cosolvent. Photopolymerization kinetics and monomer conversion were monitored in real time using attenuated total reflectance Fourier transform infrared spectroscopy and the material properties of the products were examined using gel permeation chromatography and differential scanning calorimetry. Generally, coordinated IL monomers displayed improved reaction kinetics at both high and low salt concentrations as well as distinct product properties. The noncovalent (and reversible) interactions between monomer and salt in coordinated ILs hold promise as an efficient and versatile form of structured media for photopolymerizations. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2004–2014     

Systematic Investigation of the Photopolymerization of Imidazolium-Based Ionic Liquid Styrene and Vinyl Monomers

The use of ionic liquids (ILs) as media in radical polymerizations has demonstrated the ability of these unique solvents to improve both reaction kinetics and polymer product properties. However, the bulk of these studies have examined the polymerization behavior of common organic monomers (e.g., methyl methacrylate, styrene) dissolved in conventional ILs. There is increasing interest in polymerized ILs (poly(ILs)), which are ionomers produced from the direct polymerization of styrene-, vinyl-, and acrylate-functionalized ILs. Here, the photopolymerization kinetics of IL monomers are investigated for systems in which styrene or vinyl functionalities are pendant from the imidazolium cation. Styrene-functionalized IL monomers typically polymerized rapidly (full conversion ≤1 min) in both neat compositions or when diluted with a nonpolymerizable IL, [C₂mim][Tf₂N]. However, monomer conversion in vinyl-functionalized IL monomers is much more dependent on the nature of the nonpolymerizable group. ATR-FTIR analysis and molecular simulations of these monomers and monomer mixtures identified the presence of multiple intermolecular interactions (e.g., π–π stacking, IL aggregation) that contribute to the polymerization behaviors of these systems. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2364–2375     

Large-scale molecular dynamics simulations of dense plasmas: The Cimarron Project

We describe the status of a new time-dependent simulation capability for dense plasmas. The backbone of this multi-institutional effort – the Cimarron Project – is the massively parallel molecular dynamics (MD) code “ddcMD,” developed at Lawrence Livermore National Laboratory. The project’s focus is material conditions such as exist in inertial confinement fusion experiments, and in many stellar interiors: high temperatures, high densities, significant electromagnetic fields, mixtures of high- and low-Z elements, and non-Maxwellian particle distributions. Of particular importance is our ability to incorporate into this classical MD code key atomic, radiative, and nuclear processes, so that their interacting effects under non-ideal plasma conditions can be investigated. This paper summarizes progress in computational methodology, discusses strengths and weaknesses of quantum statistical potentials as effective interactions for MD, explains the model used for quantum events possibly occurring in a collision, describes two new experimental efforts that play a central role in our validation work, highlights some significant results obtained to date, outlines concepts now being explored to deal more efficiently with the very disparate dynamical timescales that arise in fusion plasmas, and provides a careful comparison of quantum effects on electron trajectories predicted by more elaborate dynamical methods.     

p-Iodinations in hydrocarbon media: continuous flow reactor application

Regiospecific iodination of aryl amines, that is, aryl compounds possessing strong electron donating groups (EDG’s) in the p-position, is described. This procedure features not only the unique use of hydrocarbon media for such substitutions but also the absence of any oxidants aside from iodine itself. Further potential of this hydrocarbon media based electrophilic aromatic substitution is demonstrated by the coupling of the iodination with an in situ halogen/lithium exchange and product forming nucleophilic addition in a batch process. The protocol was ultimately scaled to a continuous flow reactor using an isolated p-iodoarylamine. Constituted as described, these procedures possess enhanced atom-economical, green and safety aspects compared to existing literature protocols.     

Polarization orientation dependence of the far infrared spectra of oriented single crystals of 1,3,5-trinitro-S-triazine (RDX) using terahertz time–domain spectroscopy

The far infrared spectra of (100), (010), and (001)-oriented RDX single crystals were measured as the crystal was rotated about the axis perpendicular to the polarization plane of the incident radiation. Absorption measurements were taken at temperatures of both 20 K and 295 K for all rotations using terahertz time–domain spectroscopy. A number of discrete absorptions were found ranging from 10–100 cm⁻¹ (0.3–3 THz). The absorptions are highly dependent on the orientation of the terahertz polarization with respect to crystallographic axes.     

Approximating solutions to the Dirichlet problem in Rn using one analytic function

A simpler proof is given of the result of (Whitley and Hromadka II, Numer Methods Partial Differential Eq 21 (2005) 905–917) that, under very mild conditions, any solution to a Dirichlet problem with given continuous boundary data can be approximated by a sum involving a single function of one complex variable; any analytic function not a polynomial can be used. This can be applied to give a method for the numerical solution of potential problems in dimension three or higher. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010     

Determination of urinary succinylacetone by capillary gas chromatography

The average analytical recovery of succinylacetone added to urine and separated by capillary gas chromatography was 69% for solvent extraction and 72% for anion exchange separation. Treating succinylacetone with hydroxylamine hydrochloride at a pH of less than 5 caused formation of a derivative separated by capillary gas chromatography into two isomers: 3-methyl-5- isoxazole propionate and 5-methyl-3- isoxazole propionate as their trimethylsilyl derivatives (molecular weight 227). In a pH greater than or equal to 5, succinylacetone dioxime was formed and separated into 3 isomers as their trimethylsilyl derivatives (molecular weight 404). Succinylacetone dioxime was converted to 3(5)-methyl-(3)5- isoxazole propionate whenever the pH of the solution was dropped to less than 5. Mass spectra of both derivatives are shown. This study demonstrates that capillary gas chromatography is suitable for use in urinary succinylacetone determination.