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1.
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
2.
Three kinds of micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/BMA=2/1, wt. ratio) were produced by two kinds of seeded polymerizations ofn-butyl methacrylate (BMA) in the presence of about 2 m-sized monodispersed PS particles, and their morphologies were examined. One was produced by a seeded dispersion polymerization where almost monomers and initiators exist in an ethanol/water (1/1, w/w) medium. The others two were produced by seeded polymerizations utilizing the dynamic swelling method, where almost monomers exist in the PS seed particles, with 2,2-azobisisobutyronitrile initiator in the monomer-swollen particles and with 2,2-azobis [2-(2-imidazolin-2-yl)propane] initiator in an ethanol/water (1/5, w/w) medium. In the former polymerization, the produced composite particles had a core-shell structure consisting of a PS-core and a PBMA-shell, whereas in the latter two polymerizations, they had a POO (Polymeric Oil-in-Oil) structure consisting of a PS-matrix and many PBMA-domains, regardless of the location of initiator in the systems. From these results, it is concluded that the location of BMA monomer in the seeded polymerization systems with micron-sized monodispersed PS seed particles greatly affects the morphologies of produced PS/PBMA composite particles.Part CLI of the series Studies on Suspension and Emulsion 相似文献
3.
Micron-sized, monodispersed highly styrene-“adsorbed” particles having snow-man shape were prepared by the dynamic swelling
method (DSM) with tightly cross-linked polymer seed particles as follows. First, 3.8 μm-sized monodispersed polystyrene (PS)/
poly(divinylbenzene) (PDVB) (PS/PDVB = 1/10 wt. ratio) composite particles produced by seeded polymerization utilizing DSM
were dispersed in an ethanol/water (6/4, w/w) solution dissolving styrene monomer, and poly(vinyl alcohol) as a stabilizer.
Second, water was subsequently added to the dispersion with a micro-feeder at a rate of 2.88 ml/h at room temperature. The
cross-linked seed particles adsorbed a large amount of styrene onto the surfaces and resulted in mono-dispersed highly styrene-“adsorbed”
snow-man shape particles having about 10 μm in diameter.
Received: 16 April 1998 Accepted: 9 June 1998 相似文献
4.
Micron-size monodisperse polystyrene/polydivinylbenzene (PS/PDVB) composite particles having highly crosslinked structures and vinyl groups were prepared as follows. First, 1.9 m-size monodisperse PS seed particles produced by dispersion polymerization were dispersed in ethanol/water (70/30, w/w) solution which dissolved divinylbenzene (DVB) monomer, benzoyl peroxide as an initiator and poly(vinyl alcohol) as a stabilizer. The PS seed particles were swollen with a large amount of DVB monomers to 4.3 m in diameter while keeping good monodispersity by the dynamic swelling method, where water was slowly added, continuously, with a micro feeder into the dispersion. And then, the seeded polymerization of the absorbed DVB was carried out.Part CXXXV of the series Studies on Suspension and Emulsion 相似文献
5.
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
6.
Micron-sized monodispersed polymethyl methacrylate (PMMA)/polystyrene (PS) (PMMA/PS=2/1, wt ratio) composite particles consisting
of PMMA-core and PS-shell were successfully produced by seeded dispersion polymerization of styrene in a methanol/water medium
in the presence of about 2 μm-sized monodispersed PMMA particles. From the view point of thermodynamic equilibrium, such a
morphology is difficult to form by usual seeded polymerization in a polar medium such as water. It is concluded that seeded
dispersion polymerization in which almost all monomers and initiators exist in the medium has an advantage to produce core/shell
polymer particles in which polymer layers accumulate in their order of the production regardless of the hydrophobicity of
polymers, because of high viscosity in polymerizing particles.
Received: 9 December 1996 Accepted: 26 February 1997 相似文献
7.
Micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) composite particles were produced as follows. First, 1.77 μm-sized monodispersed PS seed particles produced
by dispersion polymerization were dispersed in ethanol/water (1/2, w/w) medium dissolving poly(vinyl alcohol) as a stabilizer.
n-Butyl methacrylate (BMA) monomer dissolving benzoyl peroxide initiator was emulsified in ethanol/water (1/2, w/w) solution
of sodium dodecyl sulfate as emulsifier with ultrasonic homogenizer, and the BMA monomer emulsion was mixed with the PS seed
emulsion. The PS seed particles absorbed with a large amount of BMA (about 150 times weight of the seed particles) for 2 h
to about 10 μm in diameter while keeping good monodispersity and BMA droplets disappeared finally. The seeded polymerization
was carried out at 70 °C after a certain amount of water was added to depress the redissolving of BMA from the swollen particles
into the medium by raising from room temperature to the polymerzation temperature.
Received: 21 February 1996 Accepted: 4 September 1996 相似文献
8.
Monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles having 9.4 μm in diameter were produced by seeded polymerization for the dispersion
of highly n-butyl methacrylate (BMA)-swollen PS particles, and their morphologies were examined. The highly BMA-swollen PS particles
(about 150 times the weight of the PS seed particles) were prepared by mixing monodispersed 1.8 μm-sized PS seed particles
and 0.7 μm sized BMA droplets prepared with an ultrasonic homogenizer in ethanol/water (1/2, w/w) medium at room temperature.
After NaNO2 aqueous solution as inhibitor was added in the dispersion, the seeded polymerization was carried out at 70 °C. In an optical
microscopic observation, one or two spherical high contrast regions which consisted mainly of PS were observed inside PS/PBMA
composite particles. In the PS domain, there were many fine spherical PBMA domains. Such morphologies were based on the phase
separation of PS and PBMA within the homogeneous swollen particles during the seeded polymerization.
Received: 04 June 1997 Accepted: 27 August 1997 相似文献
9.
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
10.
Morphological investigations of crosslinked polystyrene microspheres by seeded polymerization 总被引:1,自引:0,他引:1
Crosslinked polystyrene microspheres with novel surface and inner morphologies were synthesized by seeded polymerization
following a seed-swelling method, using uncrosslinked polystyrene microspheres as seeds and a mixture of toluene, styrene
(St), and divinylbenzene (DVB) as the swelling agent. With the increasing toluene/ (St+DVB) ratio, the crosslinked particles
changed from smooth-surfaced spheres to deformed spheres with dimples or heavy dents at the surface. A single hole inside
the spherical particles was produced at low St/DVB ratio, while higher St/DVB ratios gave irregular dented or dimpled particles.
Ultrathin cross-section observation by TEM revealed a non-uniformly crosslinked inner structure.
Received: 20 January 1998 Accepted: 14 April 1998 相似文献
11.
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
12.
Zheng-You Ding Shenmin Ma Dennis Kriz J. J. Aklonis R. Salovey 《Journal of Polymer Science.Polymer Physics》1992,30(11):1189-1194
Monodisperse sized crosslinked polystyrene (PS) beads prepared by reaction of styrene (S) and divinylbenzene (DVB), in batch emulsion copolymerization in the absence of emulsifiers, are not uniformly crosslinked, because DVB is more reactive than S. For copolymerization of 1 to 10 mol % DVB and S, within each crosslinked PS microbead, the crosslink density varies by a factor exceeding two and decreases with increased conversion. A semicontinuous copolymerization, involving incremental additions of DVB, produces uniformly crosslinked PS beads. For both copolymerization techniques, Tg correlates well with crosslink density and PS beads are spherical and monodisperse in size. © 1992 John Wiley & Sons, Inc. 相似文献
13.
Micron-sized, monodispersed, electrically conductive polystyrene (PS)/polyaniline (PAn) composite particles were produced
by chemical oxidative seeded dispersion polymerization of aniline at 0 °C with 1.37-μm-sized, monodispersed PS seed particles
in HCl aqueous solution, where the pH value was kept at 2.5 with a pH stat. The composite particles consisted of a PS core
and a PAn shell. A pellet of the composite particles had a conductivity of 3.4 × 10−3 S/cm.
Received: 5 April 2000 Accepted: 10 August 2000 相似文献
14.
Micron-size monodisperse polymer particles having multihollow structures were prepared as follows. First, micron-size monodisperse polystyrene/poly(styrene-divinylbenzene) (PS/P(S-DVB)) composite particles were produced by seeded copolymerization of S and DVB with 2,2-azobisisobutyronitrile as an initiator in the ethanol/water (76/24, weight ratio) medium in the presence of 2.37 m-size monodisperse PS seed particles produced by dispersion polymerization. The molar ratio of S/DVB was changed in the range of 1/110/1. The uncrosslinked polymer within the composite particles was extracted with toluene under reflux. For the highest DVB content (S/DVB=1/1, molar ratio), one large hollow was observed in a part of the composite particles after the extraction. For the middle DVB content (S/DVB=4/1, molar ratio), multihollow structure was observed in all the particles. For the lowest DVB content (S/DVB=10/1, molar ratio), fine multihollow structure was observed in all the particles.Part CXLIII of the series Studies on Suspension and Emulsion 相似文献
15.
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
16.
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
17.
Poly(styrene) (PST) coatings of monodispersed colloidal metal oxide particles by surface grafting to poly(N-vinyl-2-pyrrolidone) (ST–PVP) or quaternized poly(4-vinylpyridine) (ST-PVPy(Me)) macromer, having a vinylphenylene end group, were investigated. Radical polymerization of styrene (ST) in ethanolic silica colloid in the presence of ST-PVP successfully led to the formation of monodispersed PST/PVP copolymer/SiO2composites. The addition of divinylbenzene (DVB) to the reaction system gave SiO2 composites coated with crosslinked PST. Graft-polymerization of ST to ST-PVP also took place on TiO2, CeO2 and Al(OH)3 colloidal particles in ethanolic solution. However, ST-PVPy(Me) adsorbed on colloidal silica did not effectively graft PST. 相似文献
18.
Haofeng Huang Huarong Liu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):5198-5205
We herein report a facile method to prepare the submicron‐sized raspberry‐like polystyrene/polyacrylonitrile particles with anisotropic properties and controllable structure via γ‐radiation‐induced seeded emulsion polymerization under ambient pressure and at room temperature, in which the monodisperse crosslinked styrene‐divinylbenzene‐acrylic acid terpolymer (P(S‐DVB‐AA)) particles were used as seed particles and acrylonitrile (AN) as the second monomer. The influence of the weight ratio of polymer/monomer, the absorbed dose rate, the absorbed dose, and the dispersion medium on the morphology of the as‐prepared particles was investigated. The final products were thoroughly characterized by Fourier transform infrared spectroscopy (FTIR), field‐emission scanning electron microscopy, and transmission electron microscopy. The results showed that the raspberry‐like particles could be fabricated in high yield. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
19.
Micron-sized mono-dispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/PBMA=2/1 by weight) having a heterogeneous structure in which many fine
PBMA domains dispersed in a PS matrix near the particle surface were produced by seeded polymerization of n-butyl methacrylate (BMA) of which almost all had been absorbed by 1.8 μm-sized monodispersed PS seed particles utilizing
the dynamic swelling method. The morphology was varied by changing the PS/BMA ratio and polymerization temperature. It was
concluded that the swelling state of 2 μm-sized BMA-swollen PS particles in the seeded polymerization process is one of the
important factors to control the morphology of the composite particles.
Received: 27 November 1996 Accepted: 21 March 1997 相似文献
20.
Polystyrene core microspheres of narrow-size distribution were prepared by dispersion polymerization of styrene in a mixture
of ethanol and 2-methoxy ethanol. Polystyrene/polychloromethylstyrene and polystyrene/poly(chloromethylstyrene-divinylbenzene)
core-shell microspheres of narrow-size distribution were prepared by seeded emulsion polymerization of chloromethylstyrene
or chloromethylstyrene and divinylbenzene in the presence of the polystyrene core microspheres at 71 °C. Core-shell particles
with different properties (size, surface morphology, and composition) have been prepared by changing various parameters belonging
to the emulsion polymerization process, e.g., volume of the chloromethylstyrene and the volume ratio of chloromethylstyrene
to divinylbenzene. Dissolution of the polystyrene core of the polystyrene/poly(chloromethylstyrene-divinylbenzene) core-shell
particles resulted in the formation of crosslinked hollow polychloromethylstyrene microspheres, broken crosslinked polychloromethylstyrene
shells, or particles containing voids, depending on the composition of the polystyrene/poly(chloromethylstyrene-divinylbenzene)
particles. 相似文献