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1.
Summary Endgroup analysis of polymethylmethacrylate obtained by initiation with thiol-dimethyl sulfoxide systems has been carried out using dye-techniques developed in our laboratory. Thiols used are 2-mercaptoethylamine hydrochloride, 2-mercaptoethanol, thioglycolic acid and n-butane thiol. The first three thiols incorporated amine, hydroxyl and carboxyl endgroup respectively to the extent of about one per macromolecule, while the last one as expected produced none of the above functional endgroups in the polymer. In the light of endgroup results initiation through thiyl radicals has been suggested. Probable termination mechanism has also been discussed.
Zusammenfassung Die Endgruppenanalyse von Polymethylmethacrylat, das durch Initiierung mit Thioldimethylsulfoxid-Systemen hergestellt war, wurde unter Anwendung unserer in unserem Labor entwickelten Färbungstechnik durchgeführt. Die verwendeten Thiole waren 2-Mercaptoäthylaminhydrochlorid, 2-Mercaptoäthanol, Thioglykolsäure und N-Butandiol. Die ersten drei Thiole fügten Amin-Hydroxyl- und Carboxyl-Endgruppen respektiv bis zum Betrag von etwa einer pro Makromolekül ein, während das letztere wie erwartet keine der oben genannten funktionalen Endgruppen im Polymer erzeugte. Aufgrund dieser EndgruppenResultate wird auf eine Initiierung durch Thiylradikale geschlossen. Der wahrscheinliche Abbruchmechanismus wird ebenfalls diskutiert.相似文献
2.
Yoshiki Chujo Kenji Kohno Noriyuki Usami Yuya Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1883-1890
Amphiphilic block copolymers, i.e., poly(methyl methacrylate)-b-poly(2-dimethylethylammoniumethyl methacrylate), were synthesized by the reaction between two prepolymers. Carboxyl-terminated poly(methyl methacrylate) and hydroxyl-terminated poly(2-dimethylaminoethyl methacrylate) were prepared by radical polymerization of the corresponding monomers in the presence of thioglycolic acid and 2-mercaptoethanol as a chain transfer agent, respectively. Two condensation methods, i.e., DCC and the acid chloride method, were used for the reactions of these prepolymers. The subsequent quarternization produced the amphiphilic block copolymers. Surface property of poly(methyl methacrylate) films containing this amphiphilic block copolymer was examined by measuring contact angles for water. The addition of only 0.5 wt% of the block copolymer was sufficient to make poly(methyl methacrylate) surfaces hydrophilic. The block copolymer formed a polymeric micelle in acetone–water mixed solvent. 相似文献
3.
Yoshiki Chujo Hisaaki Kobayashi Yuya Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):2007-2014
Hydroxyl- or amino-terminated prepolymers were prepared by radical polymerization of methyl methacrylate in the presence of 2-mercaptoethanol or 2-aminoethanethiol hydrochloride, respectively, as a chain transfer agent. The resulting prepolymers were subjected to react with trimellitic anhydride to form aromatic dicarboxyl-terminated poly(methyl methacrylate)s. These condensation-type macromonomers and terephthalic acid were condensed with bisphenol-A to produce polyester–poly(methyl methacrylate) graft copolymers. 相似文献
4.
Fernanda M. B. Coutinho Maria Jos O. C. Guimares Ailton S. Gomes 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2131-2141
The polymerization of methyl methacrylate initiated by Ce4+ methanol redox system was studied in aqueous solution of nitric acid at 15°C. The polymerization was initiated by primary radicals formed from Ce4+/alcohol complex. Poly(methyl methacrylate) chains containing the alcohol residue were obtained. Variations in the temperatuare and concentration of the components of the redox system allowed the control of the rate of polymerization and molecular weight of the polymer. The concentration of the hydroxyl end groups in the poly(methyl methacrylate) of low molecular weight was determined by titration and by spectrometric method. 相似文献
5.
Several procedures for synthesis of stereoregular poly(methacrylic acid) have been examined and the polymer characterized by (13C)NMR. Using d6 DMSO as solvent for spectroscopy gives better spectra than those previously obtained using aqueous solutions and stereochemical splittings can be resolved in the methyl signals. Free-radical polymerization in toluene solution is a Bernouilli process giving mainly heterotactic/syndiotactic polymer. Polymers produced with free-radical initiation in aqueous solution have a higher, and pH dependent, content of syndiotactic triads. A previously described procedure for producing regular polymers by hydrolysis of poly(trimethylsilyl methacrylate) requires modification to produce isotactic contents of above 90% and does not give truly syndiotactic polymer. In contrast, polymerization with γ-radiation can produce polymers with close to 90% of syndiotactic triads. 相似文献
6.
Yasuhisa Tsukahara Katsuji Ito Hsi-Chuan Tsai Yuya Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1989,27(4):1099-1114
Water-soluble graft copolymers of well-defined structure having hydrophobic polymethacrylate branches with different ester groups were prepared by the macromonomer method. Methacrylate macromonomers of controlled molecular weights having a methacryloyloxyl end group were synthesized by radical polymerization of the corresponding monomer in the presence of thioglycolic acid followed by the reaction of glycidyl methacrylate with the terminal carboxyl group. These macromonomers were copolymerized with methacrylic acid and methyl methacrylate to prepare tailor-made graft copolymers composed of a hydrophlic backbone and different kinds of hydrophobic branches, which were characterized by elemental analysis, NMR, and GPC. The viscosities of the aqueous solutions of the sodium salts of these graft copolymers were measured. It was found that the viscosity of the dilute solution of the graft copolymer was remarkably high compared with the corresponding random copolymer irrespective of the ester group in branch segments. Solubilizing behavior of Orange-OT in aqueous solutions of the graft copolymers and the random copolymer were also investigated to study the nature of the hydrophobic domain of the graft copolymers. 相似文献
7.
A series of combinations of alkyl halide with tertiary amine such as ethyl α-bromophenylacetate/tris[2-(dimethylamino)ethyl)]amine (αEBP/Me6TREN), ethyl 2-bromoisobutyrate/triethylamine (EBiB/TEA), and ethyl 2-chloropropionate/N,N,N′,N′,N′′-pentamethyldiethylenetriamine (ECP/PMDETA) have been developed as novel free radical initiators and used for the polymerizations of methyl acrylate (MA), methyl methacrylate (MMA) and styrene (St). The effects of the structure of alkyl halide and tertiary amine on the polymerization of MA were investigated. Gel permeation chromatograph (GPC) and proton nuclear magnetic resonance (1H NMR) have been utilized to analyze the end group of the obtained poly(methyl acrylate). Electron spin resonance (ESR) spectroscopy was employed to identify the structure of the radicals produced by αEBP/Me6TREN, and the results indicated that αEBP reacted with Me6TREN via a single electron transfer (SET) nucleophilic mechanism to produce corresponding ethyl α-phenylacetate radicals which subsequently initiated the polymerization of MA. As both alkyl halide and tertiary amine are commercially available at low cost, non-explosive, and ease of use and storage in comparison with conventional azo, peroxide or persulfate initiators, the combination of alkyl halide and tertiary amine as a free radical initiator is promising for large-scale practical applications. 相似文献
8.
Hydroxy‐telechelic poly(methyl methacrylate)s of molecular weights below 5000 were obtained by atom transfer radical polymerization (ATRP) of methyl methacrylate followed by end‐capping with allyl alcohol via atom transfer radical addition (ATRA). As initiators for the ATRP, monofunctional initiators with an additional hydroxy group in the molecule or bifunctional initiators were employed. The successful synthesis of the hydroxy‐telechelic PMMA was proved by determination of their molecular weight using MALDI‐TOF‐MS. The efficiency of the end‐capping reaction was determined by 1H NMR spectroscopy using the allyl N‐(4‐tolyl)carbamate as end‐capping agent. Block copolymers comprising a poly(ethylene oxide) (PEO) block and a poly(methyl methacrylate) (PMMA) block were prepared by ATRP using a macroinitiator on the PEO basis. The dormant species of the macroinitiator consists of the phenyl chloroacetate moiety which shows a high rate of initiation. The successful synthesis of the poly(ethylene oxide)‐block‐poly(methyl methacrylate) was proved by 1H NMR spectroscopy; the ratios of EO/MMA repeating units in the feed and the copolymer were nearly equal. 相似文献
9.
K. Pietrucha 《Journal of Radioanalytical and Nuclear Chemistry》1991,149(2):327-331
Thioglycolic acid is an efficient agent for controlling the lengths of poly(methyl methacrylate) (PMMA) chains grafted onto collagen. The addition of 0.006 mol of thioglycolic acid per one mol of methyl methacrylate (MMA) has no effect on the yield of grafting, but brings about a decrease in the molecular weight of grafted PMMA by about 50%. The mechanism of the grafting reaction in the presence of the chain transfer agent thioglycolic acid is discussed on the basis of the results. 相似文献
10.
Henryk Janeczek 《Journal of polymer science. Part A, Polymer chemistry》2006,44(3):1086-1092
Supramolecular complexes of alkali metals were used as catalysts in the polymerization of isoprene via a two‐electron‐transfer mechanism. The obtained polyisoprene, having a living end group, was subsequently used to initiate methyl methacrylate polymerization in tetrahydrofuran. Polyisoprene–poly(methyl methacrylate) block copolymers were obtained, and their structure was established with 1H NMR, gel permeation chromatography, differential scanning calorimetry, and experiments of selective extraction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1086–1092, 2006 相似文献
11.
D. Pramanick A. K. Chatterjee 《Journal of polymer science. Part A, Polymer chemistry》1980,18(1):311-319
The mechanism of the redox polymerization of methyl methacrylate in acid-aqueous medium was studied for ceric-thiourea initiator system by analysis of polymer end groups using the dye partition method. Polymerization at room temperature and at pH 2.30 with this initiator system incorporates mostly amino end groups in the polymers to the extent of 1.18-1.31 and a small amount of hydroxyl end group not exceeding 0.08 per polymer molecule. Under the same pH condition, a higher polymerization temperature increases the amine end group content to 2.17-2.30 and hydroxyl end group content to 0.14-0.18 per polymer molecule. A lower polymerization temperature (5°C), or a lower pH (ca. 1) of the reaction medium, produces polymers with exclusively amine end groups, hydroxyl end groups being totally absent. At pHs greater than 3, amine end group incorporation decreases significantly, with simultaneous increase in hydroxyl incorporation. On the basis of end group results the initiating radical has been identified and the mechanism of initiation has been suggested. The possible mode of termination has also been discussed. 相似文献
12.
Kiyoshi Koyama Masato Nishimura 《Journal of polymer science. Part A, Polymer chemistry》1972,10(9):2601-2608
The polymerization of vinyl monomers initiated by binary initiator systems composed of a copper–amine complex type resin and organic halides has been studied. These binary systems initiated the polymerization of various vinyl monomers. A kinetic study of the polymerization of methyl methacrylate initiated by the copper–amine complex resin–CCl4 system was carried out, and it was found that the polymerization proceeds by way of a radical mechanism. This fact was also supported by the copolymerization of methyl methacrylate with styrene. The overall activation energy of the polymerization of methyl methacrylate was estimated as 8.4 kcal/mole. The activity of the initiator systems was greatly dependent upon the dissociation energy of carbon–halogen bonds in the organic halides. A possible initiation mechanism with the binary systems is proposed and discussed. 相似文献
13.
Kiyoshi Koyama Masato Nishimura Isao Hashida 《Journal of polymer science. Part A, Polymer chemistry》1971,9(9):2439-2449
The polymerization of methyl methacrylate initiated with a peracid-type resin was studied. The peracid-type resin was prepared by the oxidation of cation-exchange resin (Amberlite IRC-50) with 60 wt-% aqueous hydrogen peroxide in the presence of p-toluenesulfonic acid. It was found that the peracid-type resin was effective as an initiator for polymerization of methyl methacrylate. The kinetic investigation indicated that this polymerization proceeded by a radical mechanism, and the overall activation energy of polymerization was 15.8 kcal/mole. No effect of macromolecular catalyst on steric structure of the resulting polymer was observed. Some graft polymer was formed in bulk polymerization. On the other hand, only a homopolymer was obtained in solution polymerization. From the results obtained, a possible mechanism of initiation with the peracid-type resin is proposed and discussed. 相似文献
14.
Thomas Stuhldreier Helmut Keul Hartwig Hcker 《Macromolecular rapid communications》2000,21(15):1093-1098
The cationic bridged zirconocene complex [iPr(Cp)(Ind)Zr(Me)(THF)][BPh4] ( 1 ‐BPh4) was synthesized. Polymerization of methyl methacrylate with 1 ‐BPh4 in CH2Cl2 at temperatures between –20 and 20°C led to the formation of isotactic poly(methyl methacrylate). The low polydispersity index of the polymer obtained and a successful two step polymerization of methyl methacrylate with 1 ‐BPh4 are hints towards a living polymerization mechanism. 1H and 13C NMR analysis revealed an enantiomorphic site‐controlled mechanism for the formation of isotactic poly(methyl methacrylate). 相似文献
15.
An environmentally friendly one-pot synthetic method based on green chemistry was developed to prepare thermodynamically partially compatible poly(2,6-dimethyl-1,4-phenylene oxide)/poly(methylmethacrylate) (PPO/PMMA) alloy in water. The oxidative polymerization of 2,6-dimethylphenol in alkaline aqueous solution was firstly conducted and then methyl methacrylate (MMA) was added into the reactor before the end of polymerization. MMA could penetrate into PPO particles and then in situ reverse atom transfer radical polymerization (RATRP) of methyl methacrylate was initiated by 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride after the oxidative polymerization. Both the oxidative polymerization of 2,6-dimethylphenol and RATRP of methyl methacrylate were catalyzed by the complex of CuCl2 and 4-dimethylaminopyridine. Finally, thermodynamically partially compatible PPO/PMMA alloy was successfully prepared which possessed a multi-layer core-shell structure with two polymers embedded in each other. 相似文献
16.
The initiation mechanism of methyl methacrylate (MMA) polymerization by organic peroxide and polymerizable aromatic tertiary amine such as N-methacryloyloxyethyl-N-methyl aniline (MEMA) binary system has been studied. The kinetics of polymerization of MMA and the ESR spectra of organic peroxide/MEMA system were determined. Based on the ESR study and the end-group analysis by UV spectra of the polymer formed, the initiation mechanism is proposed. 相似文献
17.
The polymerization of methyl methacrylate (MMA) initiated by organic peroxide and polymerizable aromatic tertiary amine such as N, N-di (2-α-methylacryloyloxy propyl)-p-toluidine (MP)_2PT binary system has been studied. It was found that the (MP)_2PT promotes MMA polymerization, and the kinetics of MMA polymerization fits the radical polymerization rate equation. Based on the ESR studies and the end-group analysis the initiation mechanism is proposed. 相似文献
18.
Walter R. Hertler 《Journal of polymer science. Part A, Polymer chemistry》1991,29(6):869-873
Diethyl vinylphosphonate does not undergo group transfer polymerization (GTP), but does react with the silyl ketene acetal end group of PMMA prepared by GTP to give α-(2-diethoxyphosphinylethyl) PMMA. Copolymerization of MMA and small amounts of diethyl vinylphosphonate led to copolymer. The telechelic PMMA diphosphonic acid, α-(2-dihydroxyphosphinylethyl) ω-dihydroxyphosphinylPMMA, was synthesized by initiation of GTP of MMA with diethyl 3-methoxy-3-trimethylsiloxy-2-propene-1-phosphonate, followed by termination with diethyl vinylphosphonate, silylation of the phosphonic ester with bromotrimethylsilane, and hydrolysis. Reaction of living poly (methyl methacrylateco-n-butyl methacrylate), prepared by GTP, with bis (trimethylsilyl) vinylphosphonate followed by hydrolysis gave α-(2-dihydroxyphosphinylethyl) poly (methyl methacrylateco-n-butyl methacrylate). 相似文献
19.
E. A. Lissi M. V. Encina 《Journal of polymer science. Part A, Polymer chemistry》1979,17(9):2791-2803
The polymerization of methyl methacrylate and styrene photosensitized by acetone, aldehydes, ethyl pyruvate, 2,3-butanedione, and 2,3-pentanedione has been investigated and the effect of several additives (carbon tetrachloride, cumene, diethyl amine, triethyl amine, 2-pentanol, and tetrahydrofuran) on initiation efficiency has been evaluated. The initiation efficiency of a given system depends on several factors, the most important of which are the relative rates of quenching by the monomers and the additives and type of product obtained. 相似文献
20.
Weidong Zhang Gaojian Chen Zhijun Hu Wei Zhang Zhengbiao Zhang Xiulin Zhu 《Journal of polymer science. Part A, Polymer chemistry》2012,50(17):3656-3663
Copper(0)‐catalyzed one‐pot reaction combining living radical polymerization and “click chemistry” was investigated. By precisely tuning reaction time, three novel well‐defined polymers with different degree of carboxyl substitution, poly(propargyl methacrylate) (PPgMA), poly(1‐(4‐carboxyphenyl)‐[1,2,3]triazol‐4‐methyl methacrylate) (PCTMMA), and poly(1‐(4‐carboxyphenyl)‐[1,2,3]triazol‐4‐methyl methacrylate‐co‐propargyl methacrylate) (PCTMMA‐co‐PPgMA) were selectively obtained via Cu(0) powder/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) cocatalyzed LRP and click chemistry. In addition, gel permeation chromatography and 1H NMR analysis in conjunction with FTIR spectroscopy elucidate that one‐pot process undergoes three steps due to a pronounced rate enhancement of click reaction: (1) generating new monomer, 1‐(4‐carboxyphenyl)‐[1,2,3]triazol‐4‐methyl methacrylate (CTMMA); (2) copolymerization of two monomers (CTMMA and PgMA); (3) building homopolymer PCTMMA. Surprisingly, in contrast to typical Cu(I)‐catalyzed atom transfer radical polymerization (ATRP), copper(0)‐catalyzed one‐pot reaction showed high carboxylic acid group tolerance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献