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111.
Christopher O. Bounds Ronald Goetter John A. Pojman Max Vandersall 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):409-422
We report a novel approach to prepare microparticles via a dispersion polymerization using the amine‐catalyzed addition of a trithiol to a triacrylate. Microparticles loaded with various core materials were produced and applied in various systems to improve the desired characteristics of the given system. We determined that this type of microparticle could be used as either a stimulated release or controlled release system for certain desired core materials. These microparticles were able to prevent the interaction between a Lewis acid initiator and fumed silica, improving the rheological properties of an epoxy system containing the initiator. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
112.
Firdaus Yhaya Arlingga Sutinah Andrew M. Gregory Mingtao Liang Martina H. Stenzel 《Journal of polymer science. Part A, Polymer chemistry》2012,50(19):4085-4093
The polymerization of vinyl methacrylate (VMA) allows the synthesis of polymers with pendant double bonds. When this polymerization was undertaken in the presence of 2‐cyanopropyl dithiobenzoate as reversible addition–fragmentation chain transfer agent, it led almost exclusively to vinylester functional sidegroups, which were available for further reactions. The vinylester functionality could not be functionalized using common thiol‐ene catalysts, but could be activated using Candida antarctica lipase B (CAL‐B) (Novozyme 435). The reaction between PVMA and various thiols in N, N‐dimethyl formamide in the presence of CAL‐B led exclusively to the formation of the anti‐Markovnikov product. The rate of reaction between PVMA and 1‐butanethiol was monitored using 1H NMR. The reaction was complete within 72 h. Similar results were obtained with other small‐sized thiols such as 2‐mercaptoethanol, 3‐mercaptopropionic acid, and 2‐(trimethylsilyl)ethanethiol, while more bulky thiols, such as secondary thiols, thiols with long alkyl chains, and sterically demanding thiols, such as mono(6‐deoxy‐6‐mercapto)‐β‐cyclodextrin, only led to lower conversions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
113.
Mateo AlajarinMarta Marin-Luna Maria-Mar OrtinPilar Sanchez-Andrada Angel Vidal 《Tetrahedron》2011,67(31):5590-5595
N[β-(Hetero)arylvinyl] ketenimines and carbodiimides bearing adequately positioned 1,3-dioxolane functions experience a new class of tandem process consisting of a 6π electrocyclic ring closure followed by a rare retro-cheletropic ene reaction, the extrusion of 2-carbena-1,3-dioxolane. This mechanistic sequence is supported by a computational study using DFT methods, showing that the simultaneous recovery of aromaticity at two rings is the clue for the low energy barrier of the retro-cheletropic step. Moreover, the highly exergonic decomposition of 2-carbena-1,3-dioxolane into CO2 plus ethylene contribute to the success of the tandem sequences. 相似文献
114.
Ting Yang Hui Long Michael Malkoch E. Kristofer Gamstedt Lars Berglund Anders Hult 《Journal of polymer science. Part A, Polymer chemistry》2011,49(18):4044-4054
Considering the large number of applications for hydrogels, a better understanding of the relation between molecular structure and mechanical properties for well‐defined hydrogel is essential. A new library has been compiled of poly(ethylene glycol) polymers (PEG) of different length end functionalized with diallyl, dithiol, and dimethacrylate, and crosslinked with complementary trifunctional crosslinkers. In this study, the hydrogels were initially analyzed by FT‐Raman and NMR to study the conversion ratio of the functional groups. The effects of solvent type, solid content concentration, curing time and length of the PEG chains on the final leaching, swelling and tensile properties of the hydrogels were studied. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
115.
116.
Carl Fredrik Carlborg Alexander Vastesson Yitong Liu Wouter van der Wijngaart Mats Johansson Tommy Haraldsson 《Journal of polymer science. Part A, Polymer chemistry》2014,52(18):2604-2615
We present a facile two‐stage UV/UV activation method for the polymerization of off‐stoichiometry thiol‐ene‐epoxy, OSTE+, networks. We show that the handling and processing of these epoxy‐based resins is made easier by introducing a material with a controlled curing technique based on two steps, where the first step offers excellent processing capabilities, and the second step yields a polymer with suitable end‐properties. We investigate the sequential thiol‐ene and thiol‐epoxy reactions during these steps by studying the mechanical properties, functional group conversion, water absorption, hydrolytic stability, and thermal stability in several different thiol‐ene‐epoxy formulations. Finally, we conclude that the curing stages can be separated for up to 24 h, which is promising for the usefulness of this technique in industrial applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2604‐2615 相似文献
117.
118.
Chang Peng Wu Pan Lin Bao Shu Chen Yi Chen Mingsong Han Yuanqin Xiong Weijian Xu 《先进技术聚合物》2014,25(6):684-688
We report a facile method that combined sol–gel reaction, reversible addition–fragmentation chain transfer (RAFT)/macromolecular design via interchange of the xanthates process and thiol‐ene click reaction to prepare monodisperse silica core‐poly(N‐vinylimidazole) (PVim) shell microspheres of 200 nm in average diameters. First, silica with C = C double bonds was prepared by the sol–gel reaction of 3‐(trimethoxysilyl)propyl methacrylates (MPS) with tetraethoxysilane in ethanol; SiO2@PVim were subsequently prepared by grafting PVim chain (Mn = 9800 g/mol, polydispersity index = 1.22) to MPS‐SiO2 via the thiol‐ene click chemisty. The obtained SiO2@PVim microspheres show higher catalytic activity toward the hydrolysis of p‐nitrophenyl acetate compared with the PVim homopolymers. The as‐prepared composites have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis and Fourier transform infrared spectrometry analysis. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
119.
The Isolation and Characterization of a Rhodacycle Intermediate Implicated in Metal‐Catalyzed Reactions of Alkylidenecyclopropanes
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Dr. Phillip A. Inglesby Dr. John Bacsa Daniela E. Negru Prof. P. Andrew Evans 《Angewandte Chemie (International ed. in English)》2014,53(15):3952-3956
The isolation and characterization of a rhodacycle intermediate implicated in rhodium‐catalyzed reactions of alkylidenecyclopropanes (ACPs) is described. The structure of the metallacycle was unambiguously determined by X‐ray crystallography and is catalytically competent in the rhodium‐catalyzed carbocyclization and ene‐cycloisomerization reactions of ACPs. This work represents a rare example of the isolation of a metallacycle in a metal‐catalyzed higher‐order carbocyclization reaction and thereby provides important insight into the ligand requirements for the insertion of π‐components. Furthermore, it serves as a convenient synthon for the development of challenging higher‐order carbocyclization reactions, as exemplified by the reaction with an activated allene. 相似文献
120.
Highly Enantioselective Carbonyl–Ene Reactions of 2,3‐Diketoesters: Efficient and Atom‐Economical Process to Functionalized Chiral α‐Hydroxy‐β‐Ketoesters
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Phong M. Truong Dr. Peter Y. Zavalij Prof. Michael P. Doyle 《Angewandte Chemie (International ed. in English)》2014,53(25):6468-6472
Carbonyl–ene reactions of 2,3‐diketoesters catalyzed by [Cu{(S,S)‐tBu‐box}](SbF6)2 [box=bis(oxazoline)] generate chiral α‐functionalized α‐hydroxy‐β‐ketoesters in up to 94 % yield and 97 % ee. The 2,3‐diketoesters are conveniently accessed from the corresponding α‐diazo‐β‐ketoester, and a catalyst loading as low as 1.0 mol % can be achieved. 相似文献