The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
David N Harpp - One of the best experts on this subject based on the ideXlab platform.
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sulfenyl chloride chemistry precursors for diatomic sulfur transfer
ChemInform, 1995Co-Authors: Imad A Abuyousef, David N HarppAbstract:When triphenylmethanesulfenyl chloride (1) (or its thio homologue 2) are treated with various bicycles, norbornene (5), or bicyclo[2.2.2]octene (6), dithio adducts 7 and 8 were produced in good isolated yields. Final products were obtained via an Episulfide intermediate. The stereochemistry of addition has been determined by X-ray analysis. Treatment of thiosulfenyl chloride 2 (or its dithio homologue 3) with other olefins, cyclopentene (10), cyclohexene (11), or 1,4-dioxene (12), leads to the formation of disulfides (13−15 from 2) and trisulfides (16 and 17 from 3) in high isolated yields (ca. 92%). The structures of 7, 8, and 13−17 were established by 1H and 13C NMR and elemental analysis as well as by X-ray determination. When these adducts are warmed with a 1,3-diene 42, they deliver diatomic sulfur-trapped derivatives, cyclic di-49 and tetrasulfide adducts 46. A variety of solvents, temperatures, times, and concentrations were employed to optimize the yield of 46 and 49. The tetrasulfide adduct 46 is...
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sulfenyl chloride chemistry sulfur transfer to double bonds
ChemInform, 1993Co-Authors: Imad A Abuyousef, Rosemary C Hynes, David N HarppAbstract:Abstract When triphenylmethanesulfenyl chloride (1) (or its thio homolog 2) are treated with various bicycles 1,2 addition reactions take place. Final products occur via an Episulfide intermediate. The stereochemistry of addition has been determined by x-ray analysis. Finally, evidence has been obtained for the delivery of diatomic sulfur, likely via intermediate 3.
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mechanism of sulfur extrusion in 2 2 dichloro 3 9 fluorenyl Episulfide
Tetrahedron Letters, 1992Co-Authors: Warren Chew, David N HarppAbstract:Abstract 2,2 Dichloro-3-[9-fluorenyl] Episulfide (2) slowly extrudes sulfur when treated thermally. The reaction generally follows unimolecular behavior but at higher concentrations in decalin, toluene and p-xylene, a bimolecular pathway is demonstrated. Kinetic and mechanistic aspects are discussed.
Yunhui Tang - One of the best experts on this subject based on the ideXlab platform.
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a novel high refractive index Episulfide thiol polymer for nanoimprinting optical elements
Journal of Materials Chemistry C, 2018Co-Authors: Yunhui Tang, Carlos Pinahernandez, Qijian Niu, Jun Nie, Stefano CabriniAbstract:A novel optical polymer with a high refractive index (n = 1.707 at 590 nm) was developed consisting of Episulfide and thiol bifunctional monomers. The Episulfide derivative of 9,9-bis(4-glycidyloxyphenyl)fluorene, synthesized by the reaction of an epoxide and inorganic thiocyanate, reacts by a ring-opening polymerization with 4,4-thiodibenzenethiol to produce the optical polymer with high transparency over the visible region of the spectrum and thermally stable up to 290 °C. The developed Episulfide-thiol optical polymer can be thermally nanoimprinted at 160 °C with nanoscale size resolution. Different nanostructures including sub-micron and nanoscale size gratings, two-dimensional photonic crystals, and plano-convex semispherical microlenses were successfully nanoimprinted with excellent pattern fidelity and low defectivity. These results exhibit the Episulfide-thiol optical polymer as a potential candidate for applications in optical and optoelectronic devices.
Nicola Tirelli - One of the best experts on this subject based on the ideXlab platform.
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combination of Episulfide ring opening polymerization with atrp for the preparation of amphiphilic block copolymers
Macromolecular Rapid Communications, 2013Co-Authors: Christopher J Cadman, Roberto Donno, Jeroen A C M Goos, Nicola TirelliAbstract:We report for the first time the combination of ATRP and ring-opening Episulfide polymerization as a means to synthesize polysulfide-based low-dispersity amphiphilic block copolymers. The most significant finding is the possibility to perform ATRP under mild conditions using poly(propylene sulfide) macroinitiators, apparently without any significant copper sequestration by the polysulfides. Using glycerol monomethacrylate (GMMA) as a hydrophilic monomer, the polymers self-assembled in colloidal structures with a morphology depending on the PS/GMMA ratio, but also probably on GMMA degree of polymerization. We here also present a new AFM-based method to calculate the average number of amphiphilic macromolecules per micelle.
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role of thiol disulfide exchange in Episulfide polymerization
Journal of Polymer Science Part A, 2008Co-Authors: Giona Kilcher, Lei Wang, Nicola TirelliAbstract:Episulfide polymerization offers a number of features that are uncommon in other ring-opening anionic mechanisms. Besides the negligible sensitivity to water, the most distinctive and novel one is likely to be the role of disulfides, which may act both at the levels of chain transfer and end-capping, producing polymers that feature both terminal and internal disulfides. In this article, we have qualitatively studied the kinetics of chain transfer and measured the thiolate-disulfide exchange equilibrium constants.
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a new living emulsion polymerization mechanism Episulfide anionic polymerization
Macromolecules, 2002Co-Authors: Annemie Rehor, Nicola Tirelli, Jeffrey A HubbellAbstract:The anionic ring-opening polymerization of Episulfides has been successfully applied in emulsion. The polymerization proceeded with a living mechanism but was characterized by a limiting conversion, presumably arising from the increase in viscosity in the polymer. To the knowledge of the authors, only two other cases of living anionic polymerization in emulsion are known (silicones and cyanoacrylates); the additional novelty presented by episulifdes is the ease of end-functionalization. Furthermore, the emulsion polymerization allowed the preparation of highly stable particles, which, due to their PEGylated surface and their appropriate diameter, can be applied in the biomedical field as nanocarriers.
Stefano Cabrini - One of the best experts on this subject based on the ideXlab platform.
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a novel high refractive index Episulfide thiol polymer for nanoimprinting optical elements
Journal of Materials Chemistry C, 2018Co-Authors: Yunhui Tang, Carlos Pinahernandez, Qijian Niu, Jun Nie, Stefano CabriniAbstract:A novel optical polymer with a high refractive index (n = 1.707 at 590 nm) was developed consisting of Episulfide and thiol bifunctional monomers. The Episulfide derivative of 9,9-bis(4-glycidyloxyphenyl)fluorene, synthesized by the reaction of an epoxide and inorganic thiocyanate, reacts by a ring-opening polymerization with 4,4-thiodibenzenethiol to produce the optical polymer with high transparency over the visible region of the spectrum and thermally stable up to 290 °C. The developed Episulfide-thiol optical polymer can be thermally nanoimprinted at 160 °C with nanoscale size resolution. Different nanostructures including sub-micron and nanoscale size gratings, two-dimensional photonic crystals, and plano-convex semispherical microlenses were successfully nanoimprinted with excellent pattern fidelity and low defectivity. These results exhibit the Episulfide-thiol optical polymer as a potential candidate for applications in optical and optoelectronic devices.
Jun Nie - One of the best experts on this subject based on the ideXlab platform.
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a novel high refractive index Episulfide thiol polymer for nanoimprinting optical elements
Journal of Materials Chemistry C, 2018Co-Authors: Yunhui Tang, Carlos Pinahernandez, Qijian Niu, Jun Nie, Stefano CabriniAbstract:A novel optical polymer with a high refractive index (n = 1.707 at 590 nm) was developed consisting of Episulfide and thiol bifunctional monomers. The Episulfide derivative of 9,9-bis(4-glycidyloxyphenyl)fluorene, synthesized by the reaction of an epoxide and inorganic thiocyanate, reacts by a ring-opening polymerization with 4,4-thiodibenzenethiol to produce the optical polymer with high transparency over the visible region of the spectrum and thermally stable up to 290 °C. The developed Episulfide-thiol optical polymer can be thermally nanoimprinted at 160 °C with nanoscale size resolution. Different nanostructures including sub-micron and nanoscale size gratings, two-dimensional photonic crystals, and plano-convex semispherical microlenses were successfully nanoimprinted with excellent pattern fidelity and low defectivity. These results exhibit the Episulfide-thiol optical polymer as a potential candidate for applications in optical and optoelectronic devices.
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synthesis and cationic photopolymerization of a difunctional Episulfide monomer
Progress in Organic Coatings, 2013Co-Authors: Jue Cheng, Feng Yang, Wenkai Chang, Jun NieAbstract:Abstract Sulfur-containing compounds have attracted many interests in the UV curing field. A new Episulfide monomer, 1,4-butanediol Episulfide (BDDGE-PSTC (BPT)), was synthesized via replacement of the oxygen atoms in 1,4-butanediol diglycidyl ether (BDDGE) with sulfur atoms. Its structure was confirmed by FTIR, 1 H NMR and ESI/MS. The photopolymerization kinetics of BPT was studied by real-time infrared spectroscopy (FTIR), under conditions with different photoinitiator concentration and type, atmosphere and so on. Physical properties such as refractive index and adhesion strength of the cured BPT polymer were studied. It was found that the cured BPT polymer showed higher refractive index and better adhesive strength on polyethylene terephthalate (PET) and iron in comparison with BDDGE. Thermal and mechanical properties of UV-curing BPT films were also investigated by TGA and DMA.