The Experts below are selected from a list of 25980 Experts worldwide ranked by ideXlab platform
Christopher N. Bowman - One of the best experts on this subject based on the ideXlab platform.
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol–Michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (<10%) of HA, which demonstrates the high selectivity of vinyl sulfones over acrylates. The reaction rate of EVS with HT was approximately 7 times higher than that of HA. A detailed study of the kinetics of the nucleophile-catalyzed thiol–Michael addition reaction was carried out, and it was shown that the delay observed in the initial stages of the nucleophile-catalyzed thiol–Michael addition reaction is due to the Relatively slow attack of the nucleophiles on the vinyl. The presence of protic species other than thiols in the reaction mixture has also been shown to significantly impede the reaction rate, and in extreme cases, has been shown to inhibit the Michael addition reaction. These results provided a better understanding of the conditions under which the thiol–Michael addition reaction can or cannot be considered as a click reaction. Finally, the high reaction selectivity of vinyl sulfones over acrylates via thiol–Michael addition reaction in ternary systems is used to control gelation behavior in crosslinked polymer networks formed by thiol–Michael addition reactions.
Shunsuke Chatani - One of the best experts on this subject based on the ideXlab platform.
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol–Michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (<10%) of HA, which demonstrates the high selectivity of vinyl sulfones over acrylates. The reaction rate of EVS with HT was approximately 7 times higher than that of HA. A detailed study of the kinetics of the nucleophile-catalyzed thiol–Michael addition reaction was carried out, and it was shown that the delay observed in the initial stages of the nucleophile-catalyzed thiol–Michael addition reaction is due to the Relatively slow attack of the nucleophiles on the vinyl. The presence of protic species other than thiols in the reaction mixture has also been shown to significantly impede the reaction rate, and in extreme cases, has been shown to inhibit the Michael addition reaction. These results provided a better understanding of the conditions under which the thiol–Michael addition reaction can or cannot be considered as a click reaction. Finally, the high reaction selectivity of vinyl sulfones over acrylates via thiol–Michael addition reaction in ternary systems is used to control gelation behavior in crosslinked polymer networks formed by thiol–Michael addition reactions.
Devatha P. Nair - One of the best experts on this subject based on the ideXlab platform.
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol–Michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (
-
Relative Reactivity and selectivity of vinyl sulfones and acrylates towards the thiol michael addition reaction and polymerization
Polymer Chemistry, 2013Co-Authors: Shunsuke Chatani, Devatha P. Nair, Christopher N. BowmanAbstract:The Reactivity, selectivity and kinetics of vinyl sulfones and acrylates in base and nucleophile-catalyzed thiol–Michael addition reactions were examined in detail in this study. The vinyl sulfones react selectively and more rapidly with thiols in the presence of acrylates, which was clearly indicated from reactions of hexanethiol (HT), ethyl vinyl sulfone (EVS) and hexyl acrylate (HA) at a molar ratio of 2 : 1 : 1. EVS reaches 100% conversion with minimal consumption (<10%) of HA, which demonstrates the high selectivity of vinyl sulfones over acrylates. The reaction rate of EVS with HT was approximately 7 times higher than that of HA. A detailed study of the kinetics of the nucleophile-catalyzed thiol–Michael addition reaction was carried out, and it was shown that the delay observed in the initial stages of the nucleophile-catalyzed thiol–Michael addition reaction is due to the Relatively slow attack of the nucleophiles on the vinyl. The presence of protic species other than thiols in the reaction mixture has also been shown to significantly impede the reaction rate, and in extreme cases, has been shown to inhibit the Michael addition reaction. These results provided a better understanding of the conditions under which the thiol–Michael addition reaction can or cannot be considered as a click reaction. Finally, the high reaction selectivity of vinyl sulfones over acrylates via thiol–Michael addition reaction in ternary systems is used to control gelation behavior in crosslinked polymer networks formed by thiol–Michael addition reactions.
F. Fleming Crim - One of the best experts on this subject based on the ideXlab platform.
-
the Relative Reactivity of ch3d molecules with excited symmetric and antisymmetric stretching vibrations
Journal of Chemical Physics, 2003Co-Authors: Sangwoon Yoon, Robert J Holiday, Edwin L Sibert, F. Fleming CrimAbstract:Experimental and theoretical studies explore the Reactivity of the symmetric and the antisymmetric stretching vibrations of monodeuterated methane (CH3D). Direct infrared absorption near 3000 cm−1 prepares CH3D molecules in three different vibrationally excited eigenstates that contain different amounts of symmetric C–H stretch (ν1), antisymmetric C–H stretch (ν4), and bending overtone (2ν5) excitation. The reaction of vibrationally excited CH3D with photolytic chlorine atoms (Cl, 2P3/2) yields CH2D products mostly in their vibrational ground state. Comparison of the vibrational action spectra with the simulated absorption spectra and further analysis using the calculated composition of the eigenstates show that the symmetric C–H stretching vibration (ν1) promotes the reaction seven times more efficiently than the antisymmetric C–H stretching vibration (ν4). Ab initio calculations of the vibrational energies and eigenvectors along the reaction coordinate demonstrate that this difference arises from change...
-
The Relative Reactivity of the stretch–bend combination vibrations of CH4 in the Cl (2P3/2)+CH4 reaction
The Journal of Chemical Physics, 2002Co-Authors: Sangwoon Yoon, Sarah Henton, Aleksandar N. Zivkovic, F. Fleming CrimAbstract:Direct infrared absorption prepares CH4 in two nearly isoenergetic vibrationally excited states, the symmetric stretch–bend combination (ν1+ν4) and the antisymmetric stretch–bend combination (ν3+ν4), for a study of the effect of stretching vibrations of CH4 on the reaction, CH4+Cl(2P3/2)→CH3+HCl. Comparison of intensities in the action spectra with those in the simulated absorption spectra shows that vibrational excitation of methane to the ν1+ν4 state promotes the reaction more efficiently than excitation to the ν3+ν4 state by a factor of 1.9±0.5. The reaction of methane in both vibrational states produces a substantial fraction (35%) of the CH3 products with the umbrella mode (ν2) excited, which we attribute to the presence of the bending vibration (ν4) in the combination states. The similarity of the vibrational population distributions of the products for the two excitations implies that the differences in the action spectra arise from the Relative Reactivity of the states rather than from population ...
-
the Relative Reactivity of the stretch bend combination vibrations of ch4 in the cl 2p3 2 ch4 reaction
Journal of Chemical Physics, 2002Co-Authors: Sangwoon Yoon, Sarah Henton, Aleksandar N. Zivkovic, F. Fleming CrimAbstract:Direct infrared absorption prepares CH4 in two nearly isoenergetic vibrationally excited states, the symmetric stretch–bend combination (ν1+ν4) and the antisymmetric stretch–bend combination (ν3+ν4), for a study of the effect of stretching vibrations of CH4 on the reaction, CH4+Cl(2P3/2)→CH3+HCl. Comparison of intensities in the action spectra with those in the simulated absorption spectra shows that vibrational excitation of methane to the ν1+ν4 state promotes the reaction more efficiently than excitation to the ν3+ν4 state by a factor of 1.9±0.5. The reaction of methane in both vibrational states produces a substantial fraction (35%) of the CH3 products with the umbrella mode (ν2) excited, which we attribute to the presence of the bending vibration (ν4) in the combination states. The similarity of the vibrational population distributions of the products for the two excitations implies that the differences in the action spectra arise from the Relative Reactivity of the states rather than from population ...
Charles U Pittman - One of the best experts on this subject based on the ideXlab platform.
-
interfacial shear strength of cured vinyl ester resin graphite nanoplatelet from molecular dynamics simulations
Polymer, 2013Co-Authors: Changwoon Jang, Thomas E Lacy, Steven R Gwaltney, Hossein Toghiani, Charles U PittmanAbstract:Abstract Interfacial adhesion between a three layer thick graphite nanoplatelet and a vinyl ester (VE) matrix was studied using molecular dynamics simulations. Polymer interphase formation near carbon surfaces influences interfacial bonding and carbon/matrix load transfer. A VE resin was equilibrated near the graphite surfaces and then cured using the Relative Reactivity Volume algorithm to form a crosslinked matrix while enforcing the correct regiochemistry and Relative Reactivity ratios within the free radical addition cure. The local styrene monomer concentration in both the liquid and cured resin was highest near the graphite sheets, affecting interfacial strength and near-surface crosslink density. The composite's glass transition temperature (466–502 K) was 50–100 K higher than pure VE. The interfacial shear strength was 141 MPa for resin with 87% monomer conversion and 106 MPa for 98% monomer conversion, indicating effective reinforcement/matrix load transfer. This computational methodology provides more chemically realistic predictions of interfacial surface adhesion than has been reported previously.
-
Relative Reactivity volume criterion for cross linking application to vinyl ester resin molecular dynamics simulations
Macromolecules, 2012Co-Authors: Changwoon Jang, Thomas E Lacy, Steven R Gwaltney, Hossein Toghiani, Charles U PittmanAbstract:Molecular dynamics simulations were performed to create a series of cross-linked vinyl ester resins. The cross-link density was varied at constant conversion. Thermodynamic and mechanical properties were calculated as a function of the cross-link density. A new Relative Reactivity volume (RRV) algorithm was developed to generate the cross-linking network by incorporating the correct regioselectivity (head-to-tail chain propagation) and monomer Reactivity ratios. This is the first application of Reactivity ratios for free radical addition polymerization in MD simulations. Prior cross-linking simulations were performed on step-growth epoxy resin curing. Vinyl esters studied here cure by free radical addition copolymerization. Cross-linked networks with double bond conversions up to 98% were achieved. Volume shrinkage, glass transition temperatures, and tensile elastic constants were calculated. Predicted Young’s moduli were compared with experimental data. This RRV method can generate other thermoset and th...
