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61.
Niyazi Bicak Mustafa Gazi Giancarlo Galli Emo Chiellini 《Journal of polymer science. Part A, Polymer chemistry》2006,44(23):6708-6716
We report application of copper‐mediated atom transfer radical polymerization in graft copolymerization of glycidyl methacrylate (GMA) from N‐bromosulfonamide groups on polystyrene‐divinyl benzene (PS‐DVB) microspheres (210–420 μm). The surface initiator groups were introduced by simple modification of crosslinked PS‐DVB (10% mol/mol) beads in three steps: (i) chlorosulfonation, (ii) sulfamidation with propylamine, and (iii) bromination. Initiation from surface‐bound N‐bromosulfonamide groups showed first‐order kinetics (k = 1.04 × 10?4 s?1 in toluene at 70 °C) and gave poly(GMA) graft chains linked to the surface by hydrolytically stable sulfonamide bonds. High graft yields were attained (up to 294.4% within 21 h) while retaining the epoxy groups. Epoxy content of the resulting product (5.41 mmol g?1) revealed an average 17 GMA repeating units in the graft per initiation site. Taking advantage of the hydrolytic stability of sulfonamide linkages and well‐known reactivity of the epoxy groups on dangling chains, “the hair‐like structure” of the polymer beads prepared can be considered when devising more efficient functional polymers as catalysts or reagent carriers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6708–6716, 2006 相似文献
62.
Selective chloroacetylations at per-2,3- and per-3-positions of β-cyclodextrin have been achieved via protection-deprotection methods. The reaction condition of pH >4 controlled by appropriate proton scavenger is essential for obtaining designed chloroacetylation degree under effective protection, as well as for high yield with less side-products. The β-cyclodextrin derivatives with 14 or 7 chloroacetyl groups are useful initiators for synthesizing star polymers with well-defined structure by atom transfer radical polymerization. 相似文献
63.
Janina Kabatc Magdalena Zasada Jerzy Pączkowski 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3626-3636
New three‐component photoinitiating systems consisting of a cyanine dye, borate salt, and a 1,3,5‐triazine derivative were investigated by measuring their photoinitiation activities and through fluorescence quenching experiments. Polymerization kinetic studies based on the microcalorimetric method revealed a significant increase in polymerization rate when the concentration of n‐butyltriphenylborate salt or the 1,3,5‐triazine derivative were increased. The photo‐induced electron transfer process between electron donor and electron acceptor was studied by means of fluorescence quenching and SrEt change of the fluorescence intensity. The experiments performed documented that an increase of the n‐butyltriphenylborate salt concentration dramatically increases the rate of dye fluorescence quenching, whereas the increasing of the 1,3,5‐triazine derivative concentration slows down the consumption of the dye. We conclude that the primary photochemical reaction involves an electron transfer from the n‐butyltriphenylborate anion to the excited singlet state of the dye, followed by the reaction of the 1,3,5‐triazine derivative with the resulting dye radical to regenerate the original dye. This reaction simultaneously produces a triazinyl radical anion derived from the 1,3,5‐triazine, which undergoes the carbon‐halogen bond cleavage yielding radicals active in initiation of a free radical polymerization chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3626–3636, 2007 相似文献
64.
65.
A bifunctional alkyl halide, namely l, 2-bis(2′-bromobutyryl) ethane (BBrBE), was synthesized and used to initiate the bulk atom transfer radical polymerization (ATRP) of styrene (St) at 110°C in the presence of CuBr/2,2′-bipyridyl. The narrow polydispersity of polystyrene (PSt) with precisely two arms could be synthesized. The initiate ability of the two active bromide functional groups at both sides of BBrBE for St and the propagation ability of the two arms were confirmed to be similar by the characterization of the individual arms obtained upon hydrolysis of the ester link between the core and the branches. 相似文献
66.
67.
The cationic polymerization of 1, 3-pentadiene was initiated by the organic azide/Et_2 AlClinitiating system in CH_2Cl_2 and n-hexane. The polymerizations were also carried out in parallelwith organic chloride/Et_2AlCl and Et_2 AlCl alone for comparison. The Et_2 AlCl- induced polymer-ization gives a low yield while the polymerization initiated by organic chloride/Et_2 AlCl producesmainly insoluble product. In contrast, the polymerization with azide/Et,AlCl has a high conver-sion and the resulting polymer having a high molecular weight is totally soluble. The SEC spectraof the polymers have clearly shown the differences between these initiating systems. 相似文献
68.
Fumio Hamazu Sumio Akashi Tatsuya Koizumi Toshikazu Takata Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1993,31(4):1023-1028
Various p-substituted benzyl p-hydroxyphenyl methyl sulfonium salts ( 2 ) were synthesized and their initiator activities were evaluated in bulk polymerization of glycidyl phenyl ether (PGE). The order of the activity was found to be 2b (X = CH3) > 2a (X = H) ≈ 2c (X = Cl) > 2d (X = NO2), indicating that the introduction of an electron-donating group enhanced the activity. In Hammett's plots, the logarithm of the ratio of the polymerization rates (log kx/kH) was correlated with σ+ρ better than with σp and a negative ρ+ value (-1.18) was obtained. Reaction of 2a with benzyl mercaptan mainly gave dibenzyl sulfide and p-hydroxyphenyl methyl sulfide. The obtained results seemed to demonstrate that the OH group of the aryl group yielded no proton as initiator for the polymerization, whereas the benzyl group caused the polymerization, which was initiated by the corresponding benzyl cation formed by C? S bond cleavage. © 1993 John Wiley & Sons, Inc. 相似文献
69.
The polymerization of metyl methacrylate (MMA) was studied in detail by use of CuCI/L as a catalyst and cholesteryl chloroformate (CC) as an initiator. It was found that the atom transfer radical polymerization of MMA could proceed when L equals to a multidentate aliphatic amine ligand, N,N,N‘,N“,N“-penta(methyl acrylate)diethylenetriamine (MA5-DETA), and no polymerization was occurred while L=2,2‘-bipyridine and 1,10phenanthroline. The linear proportionality of the molecular weights to the conversions and straight lines observed in ln[M]0/[M] versus time plots indicated that the present polymerization system had the typical controlled polymerization characteristics. 相似文献
70.
ATOM TRANSFER RADICAL POLYMERIZATION OF 2,5-BIS[(4-HEXYLOXYPHENYL)OXYCARBONYL]STYRENE 总被引:2,自引:0,他引:2
A side-on liquid crystalline monomer, 2,5-bis[(4-hexyloxyphenyl)oxycarbonyl]styrene) (HPCS), was successfully polymerized via atom transfer radical polymerization (ATRP). The polymerization was catalyzed by CuBr/PMDETA in chlorobenzene at 90℃ with (1-bromoethyl)benzene as the initiator. The polymers have narrow MWD. It is the second example of mesogen-jacketed liquid crystalline polymer (MJLCP) prepared by ATRP. 相似文献