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1.
Evaporation behavior of water from aqueous dispersions of multihollow particles prepared by the stepwise alkali/acid method 总被引:1,自引:0,他引:1
In order to clarify the formation mechanism of multihollow structures inside styrene–methacrylic acid copolymer particles
prepared by the stepwise alkali/acid method, which we proposed in 1990, the evaporation behavior of water from aqueous dispersions
of the original carboxylated particles and those after the alkali treatment and the stepwise alkali/acid treatments was examined.
It is concluded that the particle after the alkali treatment had a number of small water pools inside.
Received: 22 February 2001 Accepted: 20 June 2001 相似文献
2.
Masahiro?Okada Takumi?Matoba Masayoshi?OkuboEmail author 《Colloid and polymer science》2003,282(2):193-197
The influence of nonionic emulsifier, included inside styrene-methacrylic acid copolymer [P(S-MAA)] particles during emulsion copolymerization, on the formation of multihollow structure inside the particles via the alkali/cooling method (proposed by the authors) was examined in comparison to emulsifier-free particles. It was clarified that the nonionic emulsifier included inside the P(S-MAA) particles eased the formation of multihollow structure.Part CCL of the series studies on suspension and emulsion 相似文献
3.
Soap-free poly(styrene-ethyl acrylate-acrylic acid) latex particles with narrow size distribution and with surface carboxyl groups were synthesized by semicontinuous emulsion polymerization, and the particles with homogeneous multihollow structure were obtained after alkali posttreatment. Effects of treatment conditions and crosslinking agents on particle morphology were investigated. Results showed that the multihollow structure can be formed inside the uncrosslinked particles only when the treatment temperature exceeded 50 °C, the pH was higher than 10.0, the amount of 2-butanone was more than 3.0 ml and the treatment time was longer than 30 min. Furthermore, the volume expansion of the particles increased with the temperature increased to 90 °C, the pH to 12.5 or the amount of 2-butanone to 7.0 ml, and this value increased first and then decreased with the treatment time prolonged. Fine pores can be generated in the shell of particles crosslinked by 0.2 g of ethyl glycol dimethylacrylate (EGDMA), while no hollow structure formed inside particles when 0.4 g of EGDMA or 0.2 g of divinyl benzene was used. 相似文献
4.
Production of submicron-sized multihollow polymer particles by alkali/cooling method 总被引:5,自引:0,他引:5
Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named alkali/cooling method. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.Part CLV of the series Studies on suspension and emulsion 相似文献
5.
Rong Long Li Cheng You Kan Ze Ping Li Yi Du Yan Nan Cui Department of Chemical Engineering Key Laboratory of Advanced Materials of Ministry of Education Tsinghua University Beijing China 《中国化学快报》2007,18(6):741-743
The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization. 相似文献
6.
The formation mechanism of a multihollow structure within submicron-sized styrene/methacrylic acid copolymer particles by
the stepwise alkali/acid method, which we proposed in 1990, was discussed thermodynamically from the viewpoint of interfacial
free energy.
Received: 6 March 2001 Accepted: 17 May 2001 相似文献
7.
Eun Mi Lee Hyun Woo Lee Jae Hyeung Park Young A. Han Byung Chul Ji Weontae Oh Yulin Deng Jeong Hyun Yeum 《Colloid and polymer science》2008,286(12):1379-1385
Poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres with unique multihollow structures were prepared by suspension
polymerization in the presence of dual dispersion agents. The addition of a lipophilic emulsifier, polyethylene glycol (30EO)
dipolyhydroxystearate (Arlacel P135), not only stabilized water-in-oil (W/O) emulsion, but also converted silver nanoparticles
from hydrophilic to lipophilic. When a suspension polymerization dispersion agent, poly(vinyl alcohol), was added to the above
W/O emulsion system, a water-in-oil-in-water suspension was formed with silver nanoparticles dispersed in the oil phase. The
suspension polymerization was carried out at low temperature with 2,2’-azobis(2,4-dimethylvaleronitrile) as the initiator.
When modified silver nanoparticles were added, the rate of polymerization increased slightly. High monomer conversion (about
85%) was obtained in spite of low polymerization temperature of 30 °C. Under controlled conditions, PMMA/silver microspheres
with various hollow structures were synthesized. The PMMA/silver microspheres with multihollow structure showed high antibacterial
ability. 相似文献
8.
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
9.
采用完全无皂种子乳液聚合技术合成了粒径窄分布的P(MMA-EA-MAA)乳胶粒,通过对上述胶乳进行碱处理,制备出了具有空腔结构和多孔结构的聚合物乳胶粒,研究了交联剂的种类和用量对聚合过程、胶粒特性及胶粒结构形态的影响.结果表明,体系中加入交联剂后,单体转化率都有不同程度的提高;随交联剂用量的增加,乳胶粒粒径略有减小,交联剂用量较高时,乳胶粒粒径分布加宽;二乙烯基苯(DVB)的交联效率稍高于双甲基丙烯酸乙二醇酯(EGDMA);不加入交联剂及EGDMA用量低于0.5%时,处理后乳胶粒呈空腔结构,加入DVB及EGDMA用量高于1.0%时,处理后乳胶粒呈多孔结构,并且乳胶粒体积增量随交联剂用量的增加而减小. 相似文献
10.
The effects of pH, temperature and time in the acid-treatment process on the multihollow structure formed within submicron-sized monodispersed polymer particles by the stepwise alkali/acid method proposed by the authors were examined in detail. The original particles were produced by emulsifier-free emulsion terpolymerization of styrene, butyl acrylate, and methacrylic acid. It was clarified that the number and the size of hollows per particle were drastically changed by the acid treatment conditions as well as those in the alkali treatment process.Part CXLV of the series Studies on Suspension and Emulsion 相似文献