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61.
Jeffery BJ Whitelaw EL Garcia-Vivo D Stewart JA Mahon MF Davidson MG Jones MD 《Chemical communications (Cambridge, England)》2011,47(45):12328-12330
In this paper we demonstrate the utility of Group 4 metals for the well-controlled and stereoselective (syndiotactic) ring opening polymerization (ROP) of rac-β-butyrolactone (BBL) and their ability to form copolymers. 相似文献
62.
Miao Qi Haochuan Zhang Qi Dong Jingyi Li Rebecca A. Musgrave Yanyan Zhao Nicholas Dulock Dunwei Wang Jeffery A. Byers 《Chemical science》2021,12(26):9042
Redox-switchable polymerizations of lactide and epoxides were extended to the solid state by anchoring an iron-based polymerization catalyst to TiO2 nanoparticles. The reactivity of the molecular complexes and their redox-switching characteristics were maintained in the solid-state. These properties resulted in surface-initiated polymerization reactions that produced polymer brushes whose chemical composition is dictated by the oxidation state of the iron-based complex. Depositing the catalyst-functionalized TiO2 nanoparticles on fluorine-doped tin oxide resulted in an electrically addressable surface that could be used to demonstrate spatial control in redox-switchable polymerization reactions. By using a substrate that contained two electrically isolated domains wherein one domain was exposed to an oxidizing potential, patterns of surface-bound polyesters and polyethers were accessible through sequential application of lactide and cyclohexene oxide. The differentially functionalized surfaces demonstrated distinct physical properties that illustrated the promise for using the method to pattern surfaces with multiple, chemically distinct polymer brushes.Patterns of multiple polymer brushes on surfaces are obtained through application of an electrical potential to a surface functionalized with redox-switchable polymerization catalysts. 相似文献
63.
Zhiwei Xiao Qiang Wu Sida Luo Chuck Zhang Jeffery Baur Ryan Justice Tao Liu 《Particle & Particle Systems Characterization》2013,30(4):338-345
With incorporation of gold nanoparticles, i.e., nanorods (AuNR) and nanospheres (AuNS), into a polyurethane‐based shape‐memory polymer (SMP) EG‐72D matrix, SMP nanocomposite films capable of being remotely triggered by low‐power laser are fabricated and characterized using UV‐vis‐NIR spectroscopy, X‐ray scattering, and dynamic mechanical analysis (DMA). It is demonstrated that, with incorporation of very low concentration of gold nanorods (≈0.1 wt%), the mechanically programmed EG‐72D/AuNR nanocomposite presents rapid response to low power laser irradiation (785 nm, ≈10 mW). Comparative studies on the laser irradiation response of EG‐72D/AuNS and EG‐72D/AuNR nanocomposite films suggest that AuNRs have significantly higher photothermal conversion efficiency than AuNS and on‐resonance laser irradiation, matching the wavelength of the incident laser with the longitudinal plasmon resonance of AuNR, is necessary to induce the fast response of gold nanoparticle enabled SMP nanocomposites. 相似文献
64.
The relative cross section for the gas phase photodetachment of electrons has been determined for nitrite ions in the wavelength region 280–740 nm (4.43-1.68 eV). The vertical detachment energy for ONO? has been determined to be ≈ 2.8 eV. Evidence is presented for a new isomer of NO?2. 相似文献
65.
It is shown that every super-simple (m, n) ring is equationally complete. The atomic varieties of (m, 2) rings and the atomic varieties of (2,n) rings are completely determined. 相似文献
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We used molecular dynamics simulations to study the adsorption of aqueous uranyl species (UO(2)(2+)) onto clay mineral surfaces in the presence of sodium counterions and carbonato ligands. The large system size (10,000 atoms) and long simulation times (10 ns) allowed us to investigate the thermodynamics of ion adsorption, and the atomistic detail provided clues for the observed adsorption behavior. The model system consisted of the basal surface of a low-charge Na-montmorillonite clay in contact with aqueous uranyl carbonate solutions with concentrations of 0.027 M, 0.081 M, and 0.162 M. Periodic boundary conditions were used in the simulations to better represent an aqueous solution interacting with an external clay surface. Uranyl adsorption tendency was found to decrease as the aqueous uranyl carbonate concentration was increased, while sodium adsorption remained constant. The observed behavior is explained by physical and chemical effects. As the ionic strength of the aqueous solution was increased, electrostatic factors prevented further uranyl adsorption once the surface charge had been neutralized. Additionally, the formation of aqueous uranyl carbonate complexes, including uranyl carbonato oligomers, contributed to the decreased uranyl adsorption tendency. 相似文献
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We demonstrate that backscatter data processed by the two-point method can provide spatial loss results in a form that allows the immediate interpretation of joint loss. Furthermore, all the joints in a typical repeater span can be compared from the same base line and a threshold level introduced for the rejection or acceptance of joints, a feature which facilitates field measurement. 相似文献