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1.
The release behavior of toluene from the hollow-inside, micron-sized, monodispersed, cross-linked, polystyrene/polydivinylbenzene
composite particles which had various cross-linking densities and shell thicknesses was examined. The hollow particles were
produced by seeded polymerization utilizing the dynamic swelling method which we proposed in 1991. In comparison with that
from hollow-free particles, there was a clear difference. The cross-linking density and shell thickness of the hollow composite
particles did not affect the release rate in the former period, but did it in the latter one.
Received: 2 February 2000/Accepted: 30 August 2000 相似文献
2.
Micron-sized, monodisperse polystyrene (PS)/glycidyl methacrylate–divinylbenzene copolymer core/shell composite particles
having epoxy groups in the shells were produced by seeded dispersion copolymerization of glycidyl methacrylate and divinylbenzene
in an ethanol/water medium with 1.65-μm-sized, monodisperse PS seed particles. By chemical modifications of epoxy groups with
sodium hydrogensulfite and dimethylamine, composite polymer particles having sulfonate and dimethylamino groups, respectively,
in the shells were prepared.
Received: 13 September 2000 Accepted: 31 January 2001 相似文献
3.
Shunchao Gu Tatsuro Sakamoto Yasuyuki Yamada Daisuke Nagao Mikio Konno 《Colloid and polymer science》2007,285(5):581-586
Single-stage polymerization recently proposed for producing micron-sized polymer particles in aqueous media by Gu, Inukai
and Konno (2002) was carried out under the control of agitation with styrene monomer, an amphoteric initiator, 2,2′-azobis
[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate and a pH buffer NH3/NH4Cl at a monomer concentration of 1.1 kmol/m3 H2O, an initiator concentration of 10 mol/m3 H2O and a buffer concentration of [NH3] = [NH4Cl] = 10 mol/m3 H2O. In the polymerizations, impeller speed was ranged from 300 to 500 rpm to satisfy complete dispersion of the monomer phase
and not to introduce the gas phase from the free surface. Polymerization experiments under steady agitation indicated that
impeller speed was an important factor for size distribution of polymer particles. An increase in impeller speed promoted
particle coagulation during the polymerization to enlarge the average size of polymer particles but widen the size distribution.
To produce polymer particles with narrow size distribution, stepwise reduction in impeller speed was examined in the polymerization
experiments. It was demonstrated that this method was more effective than the steady agitation. The impeller speed reduction
could produce highly monodisperse particles with an average size of 2 μm and a coefficient of variation of size distributions
of 2.2% that was much smaller than typical monodispersity criterion of 10%. 相似文献
4.
Micron-sized, monodispersed polystyrene/poly(3,5-xylidine) composite polymer particles were produced by chemical oxidative
seeded polymerization of 3,5-xylidine with 1.37-μm-sized, monodispersed polystyrene seed particles. The chemical oxidative
seeded polymerization was conducted in an aqueous medium at 25 °C in the presence of poly(vinyl alcohol) as a stabilizer using
ammonium persulfate as an oxidant. The composite particles had a multihollow structure.
Received: 30 June 1999/Accepted in revised form: 21 October 1999 相似文献
5.
Masayoshi Okubo Teruhisa Fujibayashi Akinori Terada 《Colloid and polymer science》2005,283(7):793-798
Micron-sized, monodisperse polymer particles having unique disc-like and polyhedral shapes were produced by seeded dispersion polymerization of various methacrylates with 1.57 m-sized polystyrene seed particles in the presence of saturated hydrocarbon droplets in methanol/water. Such nonspherical shapes were controllable by the polymerization conditions.Part CCLX of the series Studies on Suspension and Emulsion 相似文献
6.
Micron-sized, monodispersed, poly(methyl methacrylate) (PMMA)/polystyrene (PS)/PMMA/PS multilayered composite particles were
successfully produced by three-step seeded dispersion polymerizations in methanol/water media. The first seeded dispersion
polymerization was carried out with 2-μm-sized, monodispersed PMMA particles. 相似文献
7.
Mizuki Ito Yumiko Furukawa Hideto Minami Masayoshi Okubo 《Colloid and polymer science》2008,286(11):1335-1341
Micrometer-sized, monodisperse, hollow polystyrene (PS)/poly(ethylene glycol dimethacrylate) (PEGDM) composite particles with
a single hole in the shell were prepared by seeded polymerization using (ethylene glycol dimethacrylate/xylene)-swollen PS
particles in the presence of sodium dodecyl sulfate (SDS). Single holes were observed at SDS concentrations above 3 mM, much
lower than in the PS/polydivinylbenzene (PDVB) system previously reported (above 45 mM). Phase separation inside droplets
occurred at lower conversion in the PEGDM system than the PDVB system. Phase separation in the droplet at the early stage
of the polymerization is an important factor for the formation of the single hole in the shell.
Part CCCXIII of the series “Studies on Suspension and Emulsion.” 相似文献
8.
Micron-sized, monodispersed polystyrene (PS)/poly (n-butyl methacrylate) (PBMA) composite particles, in which the PS domain(s) were dispersed in a PBMA continuous phase, were
produced by seeded polymerization for dispersions of n-butyl methacrylate (BMA) swollen PS particles in a wide range of PS/BMA ratios in the presence of NaNO2 as a water-soluble inhibitor. Moreover, in order to change the diameter of the composite particles at same PS/BMA ratio,
PS/PBMA (1/150 w/w) composite particles were produced using five kinds of PS particles in a range of diameters from 0.64 to
3.27 μm as seeds. The percentages of the PS/PBMA composite particles having double and triple and over PS domains, which were
thermodynamically unstable morphologies, increased with the increase in the diameter of BMA swollen PS particles. There was
a clear influence of the size of the swollen particles on the morphology of the PS/PBMA composite particles produced.
Received: 30 September 1999/Accepted: 18 April 2000 相似文献
9.
Micron-sized, monodisperse polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) (2/1 w/w) composite particles having different morphologies were prepared by the solvent-absorbing/releasing method (SARM). There was an obvious influence of the releasing rate of toluene from the toluene-swollen composite particles on the reconstructed morphology by the SARM. In the case of fast release, the reconstructed morphology was a bicontinuous structure that is similar to that formed by spinodal decomposition. On the other hand, in the case of slow release, a hemispherical structure was formed that consisted of PS and PBMA phases.Part CCLIV of the series Studies on Suspension and Emulsion 相似文献
10.
Production of micron-sized monodispersed core/shell composite polymer particles by seeded dispersion polymerization 总被引:1,自引:0,他引:1
The effect of the weight ratio of seed polymer/monomer on the morphology of the poly(methyl methacrylate) (PMMA)/polystyrene
(PS) monodispersed composite particles produced by batch seeded dispersion polymerization of styrene with 1.64-μm-sized monodispersed
PMMA seed particles in a methanol/water medium (4/1 w/w) was examined. In the PMMA/PS weight ratios of 3/1 and 2/1, the composite
particles had a clear morphology consisting of a PMMA core and a PS shell. In the ratio of 1/1, a lot of small PS domains
were observed in the PMMA core though the PS shell was still formed. By stepwise addition of styrene monomer, the formation
of the small PS domain was depressed and complete core/shell morphology was formed. Absorption/release treatments of toluene
into/from the PMMA/PS (1/1 w/w) composite particles resulted in a drastic morphological change from the core/shell structure
to a multi- layered one.
Received: 2 February 1999 Accepted in revised form: 7 April 相似文献
11.
Influence of the water-addition rate (R
w
) (ml/h) on the monodispersity of monomer-adsorbed polymer particles prepared by utilizing the dynamic swelling method (DSM)
with 1.9-μm-sized, monodispersed, loosely cross-linked polystyrene/styrene-divinylbenzene copolymer [1/(47.5–2.5), w/w] composite
particles was examined theoretically and experimentally. The thermodynamic simulation under a kinetic control state indicates
that, at the R
w
values below 4, the cross-linked composite particles adsorb all styrenes separated from ethanol/water media. The experimental
result at the R
w
value of 2.66 supported it. At the R
w
values above 5.32 and below 1.33, polydispersed styrene-adsorbed particles were prepared. The former depended on the formation
of some pure styrene droplets not containing the composite particle. The latter depended on coalescence among the adsorbed
particles by DSM.
Received: 5 April 2000 Accepted: 5 October 2000 相似文献
12.
Snowman/confetti-shaped, micron-sized, monodisperse composite particles were prepared by seeded dispersion polymerizations of n-butyl methacrylate (nBMA) with 1.28 and 2.67 m-sized polystyrene (PS) seed particles, respectively, in an ethanol/water (80/20, w/w) medium. These nonspherical composite particles consisted of one or several poly(nBMA) protuberances on the surfaces of the spherical PS particles.Part CCLXII of the series Studies on Suspension and Emulsion 相似文献
13.
Anton I. Lysikov Aleksey N. Salanov Ella M. Moroz Aleksey G. Okunev 《Reaction Kinetics and Catalysis Letters》2007,90(1):151-157
The non-template synthesis of monodisperse spherical particles of calcium carbonate is reported. Particles of a 3.5–4.5 μm
size were produced by precipitation of calcium carbonate from alcohol solution at subzero temperatures. 相似文献
14.
Influence of shell strength on shape transformation of micron-sized,monodisperse, hollow polymer particles 总被引:1,自引:0,他引:1
Micron-sized, monodisperse, non-spherical polymer particles with "rugby ball" and "red blood corpuscle"-like shapes were produced by seeded polymerization of the dispersion of (divinylbenzene/vinylbiphenyl/xylene)-swollen polystyrene particles prepared by utilizing the dynamic swelling method which the authors proposed in 1991. Their non-spherical shapes were based on buckling of the shell of the resultant hollow particles. In this article, the reversible shape transformation of the hollow composite polymer particle between spherical and such non-spherical shapes was studied in detail by controlling the shell strength. A part of the shell was buckled by external pressure which was caused by evaporation of xylene from the hollow when the shell had the tensile modulus below the critical value calculated from the pressure-buckling relationship of a spherical shell proposed by Uemura. The plasticization of the shell by a good solvent was one of key factors for the shape transformation. 相似文献
15.
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
16.
Liquid crystals (LCs) encapsulated in monodisperse micron-sized polymer particles were prepared to control the size and size
distribution of LC droplets in polymer-dispersed LCs. The poly(methyl methacrylate) (PMMA) seed particles were swollen with
the mixture of liquid crystal, monomers (methyl methacrylate and styrene) and initiator by using a diffusion-controlled swelling
method. A single LC domain was produced by the phase separation between PMMA and LC through polymerization. The optical microscopy
and scanning electron microscopy showed that the particles are highly monodisperse with core–shell structure. Moreover, monodisperse
LC core domains were confirmed from polarized optical microscope observations. The final particle morphology was influenced
by the cross-linking of the seed particle. When linear PMMA particles, which are not cross-linked, were used as a seed, the
microcapsules were distorted after annealing for a few days; however, in the case of cross-linked PMMA particles, the core–shell
structure was sustained stably after annealing.
Received: 22 November 2000 Accepted: 12 March 2001 相似文献
17.
Micron-sized monodispersed polystyrene (PS)/poly(3,5-xylidine) (PXy) composite particles were produced by chemical oxidative
seeded dispersion polymerization of 3,5-xylidine at 20 °C with 1.6-μm-sized monodispersed PS seed particles in HCl aqueous
solution, the pH of which was always kept at 2.5 with a pH stat. The composite particles produced consisted of a PS core and
a PXy shell.
Received: 16 December 1998 Accepted in revised form: 25 March 1999 相似文献
18.
4 μm-sized monodispersed cross-linked polymer particles having hollow structure were produced as follows. First, 1.7 μm-sized monodispersed polystyrene (PS) seed particles produced by dispersion polymerization were dispersed in ethanol/water (7/3, w/w) solution in which divinylbenzene (DVB), benzoyl peroxide (BPO), poly(vinyl alcohol), and toluene was dissolved. The PS seed particles were swollen with DVB, toluene and BPO maintaining high monodispersity throughout the dynamic swelling process where water was slowly added continuously. And then, the seeded polymerization of the (toluene/DVB)-swollen PS particles was carried out. 相似文献
19.
Production of micron-sized monodispersed composite polymer particles by seeded polymerization utilizing the dynamic swelling method 总被引:1,自引:0,他引:1
In order to develop the seeded polymerization technique utilizing the dynamic swelling method (DSM) proposed by authors for
the production of micron-sized mono-dispersed “composite” polymer particles consisting of two kinds of polymers, the seeded
polymerization for the dispersion of ethyl methacry-late (EMA)-swollen PS particles prepared utilizing DSM was carried out.
Monodispersed PS/poly(ethyl methacrylate) (PEMA) composite particles having 7 μm in diameter were produced by the addition
of NaCl to lower the solubility of EMA in medium and by the addition of CuCl2 as a water-soluble inhibitor to depress the by-production of submicron-sized PEMA particles.
Received: 16 July 1996 Accepted: 10 October 1996 相似文献
20.
M. Okubo E. Ise T. Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1998,36(14):2513-2519
For the purpose of extending the size range of polymer seed particles used in “dynamic swelling method” (DSM), first it was verified theoretically that the submicron-sized polymer particles produced by emulsion polymerization can also absorb a large amount of monomer by DSM in both equilibrium and kinetic control states. Next, on the basis of the theoretical results, experimentally about 2.6 μm-sized styrene-swollen polystyrene (PS) particles were prepared utilizing DSM in the presence of 0.64 μm-sized monodispersed PS seed particles produced by emulsifier-free emulsion polymerization. Moreover, 2.5 μm-sized monodispersed PS particles were produced by the addition of cupric chloride as a water-soluble inhibitor to depress the by-production of submicron-sized PS particles in the seeded polymerization at 30°C with 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) initiator. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2513–2519, 1998 相似文献