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1.
Eri Yoshida 《Colloid and polymer science》2010,288(3):341-345
In order to clarify the initiator factor dominating the molecular weight distribution of the resulting polymer, the nitroxide-mediated
photo-living radical polymerization of methyl methacrylate was performed using eight different kinds of azoinitiators: i.e.,
2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 1,1′-azobis(cyclohexane-1-carbonitrile),
racemic-(2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile), meso-(2RS,2′SR)-azobis(4-methoxy-2,4-dimethylvaleronitrile),
dimethyl 2,2′-azobis(2-methylpropionate), and 2,2′-azobis(N-butyl-2-methylpropionamide). The bulk polymerization was carried out at room temperature for 3 h using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl
(MTEMPO) as the mediator in the presence of bis(alkylphenyl)iodonium hexafluorophosphate as the photo-acid generator. All
the initiators provided a molecular weight distribution below 1.7 for the MTEMPO/initiator ratio of 2, although at the ratio
of unity, about half of the initiators produced the molecular weight distribution around 2.3–3.4. The UV analysis revealed
that the initiators having a higher ε value tended to more strictly control the molecular weight and provide a higher initiator
efficiency. The half-lives of the initiators had little effect on the molecular weight control and initiator efficiency. 相似文献
2.
Eri Yoshida 《Colloid and polymer science》2012,290(7):661-665
The photo-controlled/living radical polymerization of tert-butyl methacrylate was performed using a (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) initiator and a 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl
(MTEMPO) mediator in the presence of a (4-tert-butylphenyl)diphenylsulfonium triflate photo-acid generator. The bulk polymerization was carried out at 25 °C by irradiation
with a high-pressure mercury lamp. Whereas the polymerization in the absence of MTEMPO produced a broad molecular weight distribution,
the MTEMPO-mediated polymerization provided a polymer with a comparatively narrow molecular weight distribution around 1.4
without elimination of the tert-butyl groups. The living nature of the polymerization was confirmed on the basis of the linear correlations for the first-order
time–conversion plots and conversion–molecular weight plots in the range below 50% conversion. The block copolymerization
with methyl methacrylate also supported the livingness of the polymerization based on no deactivation of the prepolymer. 相似文献
3.
Eri Yoshida 《Colloid and polymer science》2011,289(10):1127-1132
The nitroxide-mediated photo-controlled/living radical polymerization of ethyl acrylate was attained using (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile)
as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator, and (4-tert-butylphenyl)diphenylsulfonium triflate as the photo-acid generator. The photopolymerization was performed in acetonitrile
at room temperature by irradiation with a high-pressure mercury lamp. The molecular weight distribution of the resulting polymer
decreased as the monomer concentration decreased. It was confirmed that the polymerization was controlled on the basis of
the linear correlations for the first-order time-conversion plots and the plots of the molecular weight vs. the reciprocal
of the initial concentration of the initiator, although the conversion–molecular weight plots did not show a completely linear
correlation. The block copolymerization with methyl methacrylate accompanied by no deactivation of the growing polymer chain
end supported the livingness of the polymerization. 相似文献
4.
Eri Yoshida 《Colloid and polymer science》2011,289(14):1625-1630
The nitroxide-mediated photo dispersion polymerization of methyl methacrylate (MMA) was performed by irradiation at room temperature
using (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl
(MTEMPO) as the mediator, (4-tert-butylphenyl)-diphenylsulfonium triflate as the photo-acid generator, and polyvinylpyrrolidone (PVP) as the surfactant in
a mixed solvent of methanol/water = 3/1 (v/v). The MTEMPO-mediated photo dispersion polymerization produced spherical particles of PMMA, while the uncontrolled photo
dispersion polymerization without MTEMPO provided nonspherical particles. The size distribution of the spherical particles
decreased as the PVP concentration increased. The spherical particles showed a comparatively narrow molecular weight distribution
of ca. 1.6. The livingness of the polymerization was confirmed on the basis of the linear correlations of the first-order
time–conversion plots and conversion–molecular weight plots. The simultaneous control of the size distribution and molecular
weight was possible as long as the light penetrates into the particles. 相似文献
5.
Eri Yoshida 《Colloid and polymer science》2010,288(9):1027-1030
The stability of the growing polymer chain ends for the nitroxide-mediated photo-living radical polymerization of methyl methacrylate
(MMA) was explored through block copolymerization with isopropyl methacrylate (
i
PMA). The block copolymerization of
i
PMA was performed with the PMMA prepolymer prepared by the photopolymerization of MMA using the racemic-(2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) (r-AMDV) as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) as the mediator, and (4-tert-butylphenyl)-diphenylsulfonium triflate (
t
BuS) as the photo-acid generator. When the polymerization of MMA was carried out for 6.5 h, the resulting block copolymer
showed a bimodal GPC due to the deactivation of part of the growing chain ends of the prepolymer. On the other hand, when
the MMA polymerization was shortened to 5 h, the unimodal block copolymer was obtained without deactivation of the prepolymer. 相似文献
6.
Eri Yoshida 《Colloid and polymer science》2011,289(7):837-841
Polystyrene-graft-poly(methyl methacrylate) (PSt-graft-PMMA) was prepared by the nitroxide-mediated photo-living radical polymerization using poly(4-vinylbenzyl-4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl-ran-styrene) (P(VTEMPO-r-St)) as the macromediator. The bulk polymerization of methyl methacrylate was performed at room temperature by irradiation
using a high-pressure mercury lamp with P(VTEMPO-r-St) as the mediator having the molar ratio of VTEMPO/St unit = 0.40/0.60 and the molecular weight of Mn = 21,700 and the
(2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator in the presence of the (4-tert-butylphenyl)diphenylsulfonium triflate as the photo-acid generator. The polymerization proceeded via a controlled polymerization
mechanism because both the first-order time-conversion plots and the conversion-molecular weight plots showed linear increases.
It was found that all the VTEMPO units supported the controlled PMMA chains by 1H NMR analysis because the molar ratio of the VTEMPO at the terminal chain end to the 1-cyano-3-methoxy-1,3-dimethylbutyl
group at the initiation chain end of the PMMA was unity. 相似文献
7.
Eri Yoshida 《Colloid and polymer science》2009,287(12):1417-1424
The synthesis of a poly(methyl methacrylate)-block-poly(tetrahydrofuran) (PMMA-b-PTHF) diblock copolymer was attained by the photo-living radical polymerization of methyl methacrylate using 2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO) supported on the chain end of poly(tetrahydrofuran) (PTHF) as the macromediator. The polymerization was performed
at room temperature by 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) as an initiator in the presence of bis(alkylphenyl)iodonium
hexafluorophosphate as a photo-acid generator to produce the diblock copolymer consisting of poly(methyl methacrylate) (PMMA)
and PTHF blocks connected through the TEMPO. The polymerization was confirmed to proceed in accordance with a living mechanism
based on linear correlations for three different plots of the first order time-conversion, the molecular weight of the copolymer
versus the monomer conversion, and the molecular weight versus the reciprocal of the initial concentration of the initiator.
The molecular weight distribution of the block copolymer was dependent on the molecular weight of the macromediator based
on the miscibility of PMMA and PTHF. 相似文献
8.
Eri Yoshida 《Colloid and polymer science》2010,288(2):239-243
The photo-living radical polymerization of methyl methacrylate (MMA) was performed at room temperature using (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile)
(r-AMDV) as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) as the mediator, and (4-tert-butylphenyl)diphenylsulfonium triflate (
t
BuS) as the photo-acid generator. The livingness of the polymerization was confirmed on the basis of linear increases in the
ln([MMA]0/[MMA]t) vs. time and in the molecular weight vs. the conversion. The molecular weight distributions of the resulting polymers were
around 1.45. The polymerization rate was dependent both on the
t
BuS/MTEMPO and MTEMPO/r-AMDV molar ratios. Furthermore, it was found that the polymerization had a photo-latency because the polymerization was retarded
by the interruption of the irradiation; however, it was accelerated again by further irradiation without deactivation of the
growing polymer chain ends. 相似文献
9.
Eri Yoshida 《Colloid and polymer science》2010,288(16-17):1639-1643
The photoradical polymerization of methyl methacrylate (MMA) was performed in an acetonitrile solution at room temperature using (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator, and (4-tert-butylphenyl)diphenylsulfonium triflate as the photo-acid generator. This solution polymerization showed a non-steady-state during the very early stage followed by a steady-state. The polymerization produced oligomers with several thousand molecular weights at a very low conversion under the non-steady-state. It was confirmed that the polymerization proceeded in accordance with a living mechanism under the steady-state based on the linear correlations for both the first-order time-conversion plots and the conversion–molecular weight plots. The molecular weight distributions of the polymers obtained in the steady-state were approximately 1.8. The block copolymerization with isopropyl methacrylate ( i PMA) demonstrated that the growing polymer chain ends of the MMA prepolymer were stabilized even at a high conversion and efficiently initiated the i PMA polymerization. 相似文献
10.
Eri Yoshida 《Colloid and polymer science》2010,288(1):7-13
The photoradical polymerization of vinyl acetate was performed using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO)
as the mediator in the presence of bis(alkylphenyl)iodonium hexafluorophosphate (BAI). The MTEMPO/BAI system using 2,2’-azobis(isobutyronitrile)
or 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator did not succeed in controlling the molecular weight and
produced polymers that showed a bimodal gel permeation chromatography with the broad molecular weight distribution. On the
other hand, the polymerization using 1-(cyano-1-methylethoxy)-4-methoxy-2,2,6,6-tetramethylpiperidine and BAI proceeded by
the living mechanism based on linear increases in the first order time–conversion and conversion–molecular weight plots. The
molecular weight distribution also increased with the increasing conversion due to cloudiness of the solution as the polymerization
proceeded. It was found that the polymerization had a photolatency because the propagation stopped by interruption of the
irradiation and was restarted by further irradiation. 相似文献
11.
Eri Yoshida 《Colloid and polymer science》2010,288(1):73-78
The photoradical polymerization of vinyl acetate was performed using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) as the mediator in the presence of bis(alkylphenyl)iodonium hexafluorophosphate (BAI). The MTEMPO/BAI system using 2,2’-azobis(isobutyronitrile) or 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator did not succeed in controlling the molecular weight and produced polymers that showed a bimodal gel permeation chromatography with the broad molecular weight distribution. On the other hand, the polymerization using 1-(cyano-1-methylethoxy)-4-methoxy-2,2,6,6-tetramethylpiperidine and BAI proceeded by the living mechanism based on linear increases in the first order time–conversion and conversion–molecular weight plots. The molecular weight distribution also increased with the increasing conversion due to cloudiness of the solution as the polymerization proceeded. It was found that the polymerization had a photolatency because the propagation stopped by interruption of the irradiation and was restarted by further irradiation. 相似文献
12.
Eri Yoshida 《Colloid and polymer science》2009,287(7):767-772
The novel photo-living radical polymerization of methyl methacrylate (MMA) was determined using 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile)
(AMDV) and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) in the presence of bis(alkylphenyl)iodonium hexafluorophosphate
(BAI). The polymerization provided a comparatively narrow molecular weight distribution in the range of 1.4–1.7. The resulting
PMMA contained no BAI fragments in its structure and had the 1-cyano-1,3-dimethyl-3-methoxybutyl radical and MTEMPO at the
1:1 molar ratio. The experimental molecular weight was in close agreement with the theoretical one when the initiator efficiency
was taken into consideration. The plots of ln([MMA]0/[MMA]) vs. time and the molecular weight of PMMA vs. the conversion and vs. the reciprocal of the initial concentration of
AMDV showed linear correlations, indicating that the polymerization proceeded in accordance with a living mechanism. It was
found that the polymerization had a photo-switching ability, because the polymerization was interrupted by turning off the
irradiation, and then restarted by the irradiation again. 相似文献
13.
Morphology of micron-sized monodispersed poly(butyl methacrylate)/polystyrene composite particles produced by seeded dispersion polymerization 总被引:1,自引:0,他引:1
In order to develop the seeded dispersion polymerization technique for the production of micron-sized monodispersed core/shell
composite polymer particles the effect of polymerization temperature on the core/shell morphology was examined. Micron-sized
monodispersed composite particles were produced by seeded dispersion polymerizations of styrene with about 1.4-μm-sized monodispersed
poly(n-butyl methacrylate) (Pn-BMA) and poly(i-butyl methacrylate) (Pi-BMA) particles in a methanol/water (4/1, w/w) medium in the temperature range from 20 to 90 °C. The composite particles,
PBMA/polystyrene (PS) (2/1, w/w), consisting of a PBMA core and a PS shell were produced with 2,2′-azobis(4-methoxy-2,4-dimethyl
valeronitrile) initiator at 30 °C for Pn-BMA seed and with 2,2′-azobis(isobutyronitrile) initiator at 60 °C for Pi-BMA seed. The polymerization temperatures were a little above the glass-transition temperatures (T
g) of both Pn-BMA (20 °C) and Pi-BMA (40 °C). On the other hand, when the seeded dispersion polymerizations were carried out at much higher temperatures than
the T
g of the seed polymers, composite particles having a polymeric oil-in-oil structure were produced.
Received: 14 October 1998 Accepted in revised form: 2 June 1999 相似文献
14.
Takayuki YamakawaEiji Ideue Yuzo IwakiAyumu Sato Hidetoshi TokuyamaJun Shimokawa Tohru Fukuyama 《Tetrahedron》2011,67(35):6547-6560
Three distinct synthetic routes to the 2-prenyl tryptophan core skeleton of tryprostatins and their total syntheses are described. The strategies include a traditional gramine-mediated coupling reaction, Fürstner indole synthesis, and our radical-mediated indole synthesis from o-alkenylphenyl isocyanide. The establishment of reliable conditions for the radical-mediated construction of indoles via a low-temperature radical initiator V-70 (2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile)) led to the highly efficient syntheses of tryprostatins A and B. 相似文献
15.
Eri Yoshida 《Colloid and polymer science》2012,290(11):1087-1091
The photo-controlled/living radical polymerization of methyl methacrylate using a nitroxide mediator was established in an inert atmosphere. The bulk polymerization was performed at room temperature using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator and (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate as the accelerator by irradiation with a high-pressure mercury lamp. The photopolymerization in a N2 atmosphere produced a polymer with a comparatively narrow molecular weight distribution; however, the experimental molecular weight was slightly different from the theoretical molecular weight. The Ar atmospheric polymerization also provided a polymer with the molecular weight distribution similar to that of the polymer obtained by the N2 atmospheric polymerization. These inert atmospheric polymerizations more rapidly proceeded to produce polymers with narrower molecular weight distributions than the vacuum polymerization. The livingness of the Ar atmospheric polymerization was confirmed on the basis of the first-order time–conversion plots and conversion–molecular weight plots. 相似文献
16.
V. B. Vol’eva A. I. Prokof’ev I. S. Belostotskaya A. Yu. Karmilov N. L. Komissarova T. I. Prokof’eva V. V. Ershov 《Russian Journal of Electrochemistry》2000,36(6):847-850
Solid-phase oxidation of 2,4-di-tert-butylphenol to give 2,2′,4,4′-tert-butyl-6,6′-bisphenol and of 3,6-di-tert-butylpyrocatechol to afford 3,6-di-tert-butyl-l,2-benzoquinone was performed in the presence of alkali and alkaline earth metals halides under conditions of modified
extrusion. The formation of the corresponding metal 3,6-di-tert-butylsemiquinolates was registered by ESR method. The different behavior of chlorides, bromides, and iodides was observed
and rationalized basing on the dissimilar complexing ability of halogens. The mechanism of activated oxidation was assumed.
The study was carried out under financial support of the Russian Foundation for Basic Research (grant no. 96-03-33253a).
Deceased. 相似文献
17.
Differential scanning calorimetry (DSC) was used to measure the decomposition rates of four commercially used initiators, 2,2′-azobis(isobutyronitrile) 2,2′-azobis(2,4-dimethylvaleronitrile), dilauroyl peroxide and bis(4-t-butylcyclohexyl)peroxydicarbonate, in dynamic mode, while the courses of methyl methacrylate polymerization with the listed initiators at 65, 75 and 85°C were measured isothermally. From the DSC curves, the polymerization enthalpies, the overall reaction rate constants and the activation energies for the initial steady-state polymerization were calculated. It was found that the polymerization enthalpy and the kinetic parameters depended on the type of the initiator. An initiator with a shorter decomposition half-lifetime shifted the onset of the gel effect to a higher conversion, intensified it and decreased the average molar mass of the polymer. 相似文献
18.
Synthesis, structures, and properties of spiro[6-azaperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one derivatives 总被引:1,自引:0,他引:1
V. N. Komissarov E. N. Gruzdeva L. P. Olekhnovich G. S. Borodkin V. N. Khrustalev S. V. Lindeman Yu. T. Struchkov V. A. Kogan V. I. Minkin 《Russian Chemical Bulletin》1997,46(11):1924-1930
The reaction of 5-amino-4-chloroquinolines with 4-amino-2,6-di-tert-butylphenol yielded derivatives of spiro[6-azaperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one, which exhibit photo-and thermochromic
properties in solutions. The structure of 2′,6′-di-tert-butyl-5,7,9-trimethylspiro[6-aza,-2,3-dihydroperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one was established by X-ray diffraction
study. The ring-chain isomerization of 2′,6′-di-tert-butyl-5,7-dimethyl-and 2′,6′-di-tert-butyl-5,7,8-trimethylspiro[6-aza-2,3-dihydroperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-ones was studied by dynamic NMR spectroscopy.
Deceased.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2028–2034, November, 1997. 相似文献
19.
Emulsifier-free emulsion copolymerization of styrene and acrylamide using an amphoteric initiator 总被引:2,自引:0,他引:2
S.-J. Fang K. Fujimoto S. Kondo K. Shiraki H. Kawaguchi 《Colloid and polymer science》2000,278(9):864-871
Emulsifier-free emulsion copolymerization of styrene (St) and acrylamide (AAm) has been investigated in the presence of an
amphoteric water-soluble initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine]hydrate (VA057). The kinetics of polymerization and the colloidal properties of
the resulting latices were studied and compared with the cases using ionic initiators. When adopting the amphoteric initiator
at pHs lower than 10, stable amphoteric poly (St/AAm) latices, evidenced by the electrophoretic mobility, were prepared directly.
Meanwhile, almost the same conversion versus time curves appeared and there were no apparent differences in the final particle
sizes for those polymerizations, whereas in the polymerization at pH 10, a much lower rate of copolymerization and a larger
size of particles were observed. The surface charge density and the growth rate of latex particles produced with VA057 at
pH<10 were comparable to those of the particles with a cationic initiator, 2,2′-azobis(2-amidinopropane)dihydrochloride, but
were apparently lower than those with an anionic initiator, potassium persulfate, when the polymerizations were carried out
under corresponding conditions. The number of initiator fragments incorporated onto the particle surfaces was independent
of polymerization pH, except for pH 10. The abnormal performance of VA057 at pH 10 was attributed to its degradation due to
hydrolysis.
Received: 14 December 1999 Accepted: 22 February 2000 相似文献
20.
G. A. Abakumov V. I. Nevodchikov N. O. Druzhkov L. N. Zakharov L. G. Abakumova Yu. A. Kurskii V. K. Cherkasov 《Russian Chemical Bulletin》1997,46(4):771-776
New di-o-quinones of the biphenyl series, namely, 2,2′-dialkyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinones, were synthesized. Their structures were established by IR and NMR spectroscopy. The molecular
structure of 2,2′-dimethyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinone was established by X-ray structural analysis. The structure is characterized by orthogonal
(the torsion angle is 82.9°) mutual arrangement ofo-benzoquinone fragments. ESR studies demonstrated that chemical reduction of diquinone proceeds in four oneelectron stages
to form paramagnetic mono- and trianions as intermediates. Quinopyrocatechols, which are intermediates in the synthesis of
di-o-quinones, were isolated and characterized.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 804–809, April, 1997. 相似文献