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本文在介绍常规乳状液、微乳液和固体稳定乳液的基础上,着重综述了纳米粒子稳定乳液的特点及其在纳米结构合成中的应用进展,并对目前该研究领域亟待解决的问题进行了分析。纳米粒子稳定乳液具有独特的油、水、固三相环境和水油、水固、油固三个相界面,分散相液滴尺寸可以在微米、亚微米乃至纳米尺度调节,因而可以作为合成组成、结构和性能极为丰富多样的纳米结构的介质。纳米粒子对乳液稳定作用的机理,以及纳米粒子稳定乳液中化学反应的特殊规律还有待深入研究。本文在介绍固体稳定乳液的基础上,着重综述了纳米粒子稳定乳液的特点及其在纳米结构合成中的应用进展,并对目前该研究领域亟待解决的问题进行了分析。纳米粒子稳定乳液具有独特的油、水、固三相环境和水油、水固、油固三个相界面,分散相液滴尺寸可以在微米、亚微米乃至纳米尺度调节,因而可以作为合成组成、结构和性能极为丰富多样的纳米结构的介质。纳米粒子对乳液稳定作用的机理,以及纳米粒子稳定乳液中化学反应的特殊规律还有待深入研究。 相似文献
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本文报道DTT还原,DTNB氧化以及NEM修饰对小鼠肝膜巯基含量和与胰岛素受体特异结合的影响。DTT还原导致膜巯基含量和与胰岛素特异结合平行增加,Scatchard分析表明胰岛素结合位点的数目仅有微小变化,但结合常数增高到原来的二倍。用含有DTT的缓冲液洗涤已饱和结合了胰岛素的膜比用不含DTT的缓冲液,导致结合在膜上的胰岛素解离下来的量明显升高,说明有一部分胰岛素与其受体的结合是通过巯基—二硫键交换反应形成共价的二硫键。加入DTT使这种“二硫键联接”的胰岛素也从受体上解离下来。DTNB或NEM对膜与胰岛素的特异结合几乎没有影响,但对已被DTT还原的膜似有逆转DTT还原的效应,推测,鼠肝膜胰岛素受体上可与胰岛素发生共价结合的巯基中,有一部分是不能与DTNB发生反应的,DTT处理膜使胰岛素受体产生更多的巯基而使胰岛素特异性结合,特别是使通过共价二硫键的结合增加。 相似文献
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碘甲烷在碳酸二甲酯直接合成中的作用 总被引:4,自引:0,他引:4
Dimethyl carbonate (DMC) is an environmentally friendly compound and a substitutive intermediate for highly toxic phosgene or dimethyl sulfate in carbonylation and methylation reactions as well as a promising octane booster. The common methods for its preparation are the oxidative carbonylation of methanol catalyzed by a variety of transition metal ions and the transesterification of ethylene carbonate or propene carbonate with methanol[1]. The direct synthesis of DMC from carbon dioxide and methanol is a challenging route in which the most abundant carbon resources and a main greenhouse gas is used as feedstock. A new method for the direct synthesis of DMC catalyzed by the methoxide of main group metal has attracted more and more attention since it was reported[2~6] . However the lower conversion of the reaction has become the main obstacle for its application. In this letter, an efficient promoter for the direct synthesis of DMC is reported. 相似文献
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乳化剂对聚硅氧烷乳液稳定性的影响 总被引:3,自引:0,他引:3
研究了乳化剂烷基酚聚氧乙烯醚(OP)、烷基聚氧乙烯醚和烷基季铵盐对聚硅氧烷乳液聚合的影响。采用复合乳化剂可以提高乳液稳定性。结果表明:①在以D4、N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷为原料的乳液聚合中。当非离子型乳化剂烷基聚氧乙烯醚和离子型乳化剂烷基季铵盐复合使用时,二者性能互补,产生协同效应,可使聚合物乳液具有很大的稳定性。②在实验选定的乳化剂中,非离子型烷基聚氧乙烯醚乳化剂用量为80mL(含量为0.05g/mL)、离子型烷基季铵盐乳化剂为60mL(浓度为0.05g/mL)时。其乳液的电解质稳定性、pH稳定性、冻融高温稳定性和离心稳定性等较好。 相似文献
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用荧光探针(芘)法测定了十二烷基硫酸钠(SDS)、烷基酚聚氧乙烯醚(OP-10),以及复配乳化剂的临界胶束浓度(CMC),并首次把荧光探针技术应用到硅/丙核壳乳液聚合反应的研究中.利用芘的I1/I3值,结合胶束微环境的极性变化规律和乳液聚合机理,探讨了乳化剂对聚合反应的影响.结果表明,荧光探针(芘)法可用于研究硅/丙乳液的聚合行为和确定乳化剂配比.通过粒径分析、透射电镜(TEM)对产品的结构进行了表征. 相似文献
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乳化剂对阳离子乳液聚合及乳胶粒性能的影响 总被引:1,自引:0,他引:1
以苯乙烯、丙烯酸丁酯为非离子单体,甲基丙烯酰氧乙基三甲基氯化铵(DMC)为阳离子单体,偶氮二异丁基脒盐酸盐(AIBA)为引发剂,十六烷基三甲基氯化铵(CTAC)和乙撑基双(十六烷基二甲基氯化铵)(G16—2—16)为乳化剂,采用半连续种子乳液聚合法进行阳离子乳液聚合。探讨了乳化剂的分子结构和用量对反应速率、单体转化率以及乳胶粒粒径、Zeta电位等的影响。结果表明:乳化剂的用量越大,反应速率越大,单体转化率越高,而乳胶粒粒径越小;使用G16—2—16作乳化剂时,单体转化率较高,乳胶粒粒径较大,Zeta电位较高。 相似文献
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K. Ni E. Bourgeat-Lami N. Sheibat-Othman G. Shan G. Fevotte 《Macromolecular Symposia》2008,271(1):120-128
Hybrid nanoparticles with a polystyrene core and a hybrid copolymer shell were used to produce hybrid nanocapsules by dissolving the polystyrene core from the previously elaborated core-shell particles. Following previous works, the core-shell particles were prepared by emulsion polymerization of styrene and subsequent addition of γ-methacryloxy propyl trimethoxy silane (MPS) to produce the shell by copolymerization reaction of MPS with the residual styrene. Core extraction was performed by diluting the core-shell particles in an excess of tetrahydrofuran (THF). Two procedures were investigated to separate the dissolved polymer chains from the nanocapsules. In the first procedure, the polymer was isolated by successive centrifugation and redispersion in THF, whereas in the second procedure, the free polymer chains were removed by dialysis. The polymer molecular weight was optimized in order to promote dissolution of the polymer chains and allow them to diffuse through the shell. 相似文献
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Ayfer Saraç 《Macromolecular Symposia》2004,217(1):161-168
The semicontinuous emulsion copolymerization of vinyl acetate and butyl acrylate (VAc/BuA) (85:15) initiated by thermal initiators ammonium persulfate (APS) and potassium persulfate (PPS) at 70°C in the presence of nonylphenol ethoxylates of varying chain lengths (NP-n) and acrylamide partially polymerized (Amol) was investigated. VAc-BuA copolymer latexes were synthesized as two different series in the glass reactor, in the first serie was initiated by APS and PPS was used as initiator in the second serie. The influence of the counterions or initiators and chain lenghts of non-ionic emulsifier on the properties of VAc-BuA copolymer latexes were determined by measuring Brookfield viscosities, weight average molecular weights (M̄w), number average molecular weights (M̄w), molecular weight distribution and surface tension of latexes to air. The results of copolymer latexes indicated that their physicochemical properties increased with the increasing chain length of nonionic emulsifier for two initiators. 相似文献
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Qing Ye Liang-Fang Zhai Nian-Nian Fan De-Ping Lu 《Journal of Dispersion Science and Technology》2013,34(6):859-869
The poly(methyl methacrylate/butyl acrylate/acrylic acid) [P(MMA/BA/AA)] and poly (styrene/butyl acrylate/acrylic acid) [P(St/BA/AA)] latexes were synthesized using the emulsifier octylphenol polyoxyethylene(10) ether (OP-10) and ammonium sulfate allyloxy nonylphenoxy poly(ethyleneoxy)(10) ether(DNS-86). The optimum amount of OP-10 and DNS-86 was 1.5% and 2.5% respectively. The P(MMA/BA/AA) and P(St/BA/AA) latex containing 1.5% OP-10 or 2.5% DNS-86 were blended pairwise. The performances of latex blends and parent latexes as a function of emulsifiers content in parent latexes were determined. The results indicated that the stability of latex blends is favorable, and particle size distribution was more uniform and thermal stability was improved after blending. 相似文献
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Xinyan Xiao Ye Wang 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):151-156
An emulsifier-free fluorinated polyarcylate emulsion was synthesized by a seed emulsion polymerization method from methyl methacrylate (MMA), butyl acrylate (BA) and hexafluorobutyl methacrylate (HFMA) in the presence of a polymerizable emulsifier—ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86). Influences of the DNS-86 level on electrolyte stability of the emulsifier-free emulsion were discussed. In addition, the emulsion and the films were characterized by Fourier transformed infrared (FT-IR) spectrometry, nuclear magnetic resonance (1H NMR) spectrometry, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), thermogravimetry (TG), and contact angle (CA) analysis, respectively. The FT-IR spectra and 1H NMR spectrum showed that HFMA was effectively involved in the emulsion copolymerization and monomers formed the fluorine-containing acrylate copolymer. The resulted emulsion particles had a core–shell structure and a narrow particle size distribution. XPS and CA analysis revealed that a gradient concentration of fluorine existed along the depth profile of the fluorine-containing emulsion film. One side of the film was richer in fluorine and more hydrophobic than the other side. The film formed from the fluorine-containing emulsion showed higher thermal stability than that of the fluorine-free emulsion. 相似文献