Measurement and modeling of peroxides half-life: A thermo-kinetic approach

Half-life values of organic peroxides at elevated temperature conditions are important in characterizing the reactivity and are often available in literature or through vendors. However, there is often lack of details/accuracy on methods used to obtain these values, as well as differences in methods across vendors and publications, thus resulting in discrepant reactivity profile. To address this, a method involving calorimetric experiment and thermo-kinetic modeling was developed. The current approach was applied on five peroxides samples to obtain kinetic parameters and estimate their half-life in the temperature range of interest. The measurements were performed by DSC under non-isothermal conditions on the dilute peroxide solutions (∼0.12 M in mineral oil) and the data were kinetically treated according to three model-based and one model-free kinetic equations. A very good agreement was found between the half-life calculated by all kinetic methods, but significant differences were noticed with the kinetic parameters reported in literature. Additionally, the obtained half-life results, based on non-isothermal measurements developed kinetic models, were validated through isothermal calorimetric testing. Given the accuracy and robustness of our results, the current method can be applied to estimate half-life of organic peroxides at elevated temperature conditions.     

Basic Interval Orders

An interval order of length n has elements in correspondence with a collection of intervals in the linearly ordered set {1, 2, ..., n}. A basic interval order of length n has the property that removal of any element yields an order with length less than n. We construct and enumerate the set of basic length n interval orders.     

Lithium bis(2‐phenylphosphidoethyl)phenyl‐phosphine: A reactive phosphorus intermediate

Bis(2‐phenylphosphinoethyl)phenylphosphine, PhP(CH₂CH₂PPh₂)₂, reacts with lithium in tetrahydrofuran to give the corresponding lithium bis(2‐diphenylphosphidoethyl)phenylphosphine, Li₂[PhP(CH₂CH₂PPh)₂]. The lithium diphosphide is identified by NMR spectroscopy and further characterized through arylation with excess brombenzene to reform the starting phosphine, PhP(CH₂CH₂PPh₂)₂. Initial reactivity studies of the diphosphide, PhP(CH₂CH₂PPh), with some alkylhalides are also described. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:675–678, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20351     

Nanostructure stability and swelling of ternary block copolymer/homopolymer blends: A direct comparison between dissipative particle dynamics and experiment

Ternary block copolymer (BCP)‐homopolymer (HP) blends offer a simple method for tuning nanostructure sizes to meet application‐specific demands. Comprehensive dissipative particle dynamic (DPD) simulations were performed to study the impact of polymer interactions, molecular weight, and HP volume fraction (φ_HP ) on symmetric ternary blend morphological stability and domain spacing. DPD reproduces key features of the experimental phase diagram, including lamellar domain swelling with increasing φ_HP , the formation of an asymmetric bicontinuous microemulsion at a critical HP concentration ${\phi }_{\mathrm{HP}}^{*}$, and macrophase separation with further HP addition. Simulation results matched experimental values for ${\phi }_{\mathrm{HP}}^{*}$ and lamellar swelling as a function of HP to BCP chain length ratio, α = N_HP/N_BCP . Structural analysis of blends with fixed φ_HP but varying α confirmed that ternary blends follow the wet/dry brush model of domain swelling with the miscibility of HPs and BCPs depending on α . Longer HPs concentrate in the center of domains, boosting their swelling efficiencies compared to shorter chains. These results advance our understanding of BCP‐HP blend phase behavior and demonstrate the value of DPD for studying polymeric blends. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 794–803     

Molecular Dynamics Study of the Photodissociation of ICN in Ethanol: Effect of Solvent Polarity

Journal of Solution Chemistry - In this work the photodissociation process for ICN in ethanol, a moderately polar solvent, was simulated using semi-classical molecular dynamics. Comparisons of the...