不同尺寸（0.02—0.5μm）单分散聚苯乙烯乳液微球的制备

通过对苯乙烯乳液聚合微观动力学以及聚合过程中胶粒直径及其分布随时间变化的理论分析,并通过实验验证,比较了不同乳化剂种类、不同反应温度和不同单体用量条件下,产物胶乳的粒径分布,发现乳液聚合最终产物的粒径分布与成核期长短没有直接联系,而是取决于自由基进入胶粒的速率常数、稳态增长时间、胶粒中的平均自由基数目和胶粒的体积增长速率,胶乳单分散性随这些参量的增大而提高,从而解释了采用高温、高引发剂浓度以及长时间反应的条件对最终的胶粒尺寸分布的影响。本文还通过实验,找到了在20～500nm范围内控制粒径大小及粒径分布的方法。在20～100nm的范围内,用一步法乳液聚合,通过改变单体用量和乳化剂浓度,制备了一系列粒径的单分散聚苯乙烯胶乳;在100～500nm的范围内,运用种子乳液聚合,通过改变溶胀单体与种子胶乳的用量比,也制得了不同粒径的单分散聚苯乙烯胶乳。     

MMA-EA-AA无皂乳液聚合中粒径及粒径分布的控制

系统研究了MMA EA AA三元无皂乳液聚合体系中各种因素对乳胶粒大小及分布的影响 ,制得了单分散、粒径在 30 0～ 6 0 0nm可控聚合物乳胶粒 .结果表明 ,在过硫酸铵用量一定的条件下 ,聚合初期加入大量引发剂可同时提高单体转化率和乳胶粒的单分散性 ;随着引发剂和AA用量的增加以及聚合温度的升高 ,胶粒粒径逐渐减小 ,转化率逐渐升高 ;随着NH4 HCO3用量的增加 ,粒径逐渐增大 ,当NH4 HCO3用量达到 0 5g以后 ,转化率逐渐降低 ;搅拌速率为 30 0r min左右时 ,单体转化率最高 ,所得乳胶粒粒径最均一 .     

高表面电荷密度单分散苯乙烯磺酸钠纳米微球的制备

利用无皂乳液聚合 ,在苯乙烯 (St)的反应体系中引入适量的苯乙烯磺酸钠 (NaSS)参加共聚合 ,在聚合过程中分两阶段加料 ,第一阶段中NaSS浓度是决定乳胶粒粒径及单分散性的关键因素。当反应达到较高转化率 ( >90 % )时加入第二阶段单体混合物 ,此阶段中NaSS与St的比例决定了最终胶粒的表面电荷密度。利用上述两阶段无皂乳液聚合法成功地制备了粒径小于 10 0nm、单分散性指数小于 1.0 5以及表面电荷密度大于 3 0 μC·cm-2 的一系列乳胶粒     

新型高活性催化剂乙烯气相聚合的研究（Ⅱ）——改性剂,预聚…

研究了新型高活性乙烯气相聚合催化剂ＴｉＣｌ４／ＭｇＣｌ２／ＺｎＣｌ２／ＳｉＣｌ４醇／Ａｌ（ｉ－Ｂｕ）３体系中不同醇、不同Ｃ２Ｈ５ＯＨ／Ｔｉ摩尔比和正丁醚对聚合反庆及产物颗粒形态的影响，研究了预聚合反应及乙烯气相聚合反应规律，用扫描电镜和图象分析对催化剂、预聚物和聚合产物的形态和颗粒分布的研究表明：新型高活性催化剂和经预聚合制得的乙烯气相聚合物的颗粒形态类似球形，颗粒长短轴比值和大小粒径比值相近。     

醋酸乙烯酯-丙烯酸丁酯乳液聚合成核机理

本工作研究了醋酸乙烯酯(VA)和丙烯酸丁酯(BA)乳液共聚合.通过对不同共聚单体配比下共聚合时胶乳粒径及胶粒数密度随转化率变化的分析,对VA/BA乳液共聚合成核及粒增长机理进行了探讨,指出水相成核是高VA含量时胶粒数密度较大的主要原因并解释了胶粒数密度及胶乳粒径与单体转化率的关系,同时也讨论了该共聚体系一步法聚合时反应机理与胶粒形态的关系.     

交联剂对无皂P(MMA-EA-MAA)种子聚合乳胶粒成孔的影响

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.     

纯化对三元无皂共聚胶粒性质的影响

以离子交换和高速离心两方法纯化含不同功能基的三元无皂共聚胶乳,用ＴＥＭ和电导滴定检测比较了以上两方法的纯化效果,同时考察了这两种纯化方法对三元无皂胶粒形态,大小及表面功能其量的影响。研究发现,只有通过多次离心－倾析－再分散过程才能将胶乳所有杂质除去。离子交换和离心纯化不影响胶粒形态大小,而离心纯化使粒表面功能其量发生显著变化。     

二氧化碳加氢合成二甲醚的研究——ZrO2含量对Cu—ZnO—SiO2—ZrO2催 …

考察了ＣＯ２加氢合成ＣＨ３ＯＣＨ３反应中ＺｒＯ２含量对Ｃｕ－ＺｎＯ－ＳｉＯ２－ＺｒＯ２催化剂的影响,采用ＴＰＲ,ＸＲＤ,ＢＥＴ和ＴＥＭ等技术对催化剂的结构形态、表面性质和ＺｒＯ２的作用进行了研究,结果表明,催化剂中加入ＺｒＯ２能提高催化剂的比表面积及ＣＯ２转化率和ＣＨ３ＯＣＨ３产率,降低最佳反应温度;ＺｒＯ２含量以２％～３％为佳,催化剂中的ＣｕＯ以种形式存在：小晶粒ＣｕＯ,聚集的无定形ＣｕＯ及均匀     

三元聚合物复合颗粒的制备与形态调控

分别考察了聚合过程中的各因素对三元聚合物复合颗粒大小与形态的影响,结果表明:在分散共聚中,复合颗粒的粒径主要由疏水性单体苯乙烯的聚合所决定;并可采用分步聚合的方法先制备目标粒径的种子微球,进而在种子分散聚合过程中实现对颗粒大小的有效控制,其范围在500nm到3μm之间;颗粒表面凸起的不同形态是由聚丙烯腈链的生长和堆积所决定,但受到反应介质性质与聚合温度等条件的影响。     

亲水性咔唑共聚物和钼簇合物之间的作用及其溶液荧光

研究了Ｎ－乙烯基咔唑－丙烯酸共聚物（ＮＶＣ－ＡＡ）和微量的钼簇合物「Ｍｏ３Ｏ２（Ｏ２ＣＣＨ３）６（Ｈ２Ｏ）３」Ｂｒ２．２Ｈ２Ｏ在水溶液相互作用及其溶液荧光。实验发现,体系中存在单体荧光（３７５ｎｍ）和二聚体激态缔合物荧光（５００ｎｍ）。荧光强度分别随钼簇合物的浓度啬和ｐＨ值的提高而增强。     

Miniemulsion polymerization of styrene: Evolution of the particle size distribution

The mechanism of the miniemulsion polymerization of styrene was investiaged through a combination of calorimetry to monitor the polymerization rate and transmission electron microscopy (TEM) to follow the evolution of the particle size distribution. These techniques proved to be a powerful combination for gaining detailed mechanistic information regarding these polymerizations. Particle size analysis of the latexes withdrawn during the course of the reaction revealed that most of the polymer particles were formed by a relatively low conversion (i.e., 10% conversion). However, nucleation continued well past this point (to 40-60% conversion). In fact, it was observed that nucleation in miniemulsion polymerizations using cetyl alcohol continued past the maximum in the rate of polymerization. As a result of these long nucleation periods, the latex particle size distributions produced from these miniemulsion polymerizations were broader than their conventional emulsion polymerization counterparts, and were negatively skewed with a tail of small particles. The amount of negative skewing of the particle size distributions was found to decrease with increasing initiator (potassium persulfate) concentration. Finally, a correlation was observed between the length of time to the maximum polymerization rate and the breadth of the particle size distribution as reflected in the standard deviation. © 1995 John Wiley & Sons, Inc.     

Effect of crystallite size on the catalysis of alumina-supported cobalt catalyst for steam reforming of ethanol

The selectivity for steam reforming of ethanol on alumina-supported cobalt catalysts is closely related to the crystallite size of cobalt, which varies the strength of ethanol adsorption.     

Extension of the Taylor Equation for Oil-Water-Surfactant System and Investigating the Impact of Surfactant Concentration over the Quality of Emulsion

Emulsions stand among the most important multiphase fluids, exhibiting various complicated phenomenon. To understand the process of emulsification, the Taylor equation has been extended to incorporate the parameters that depend on molecular mass of oil and their contents and the amount of surfactant added. To test the validity of the proposed equations, four well-defined short chain (n-hexane, n-heptane, n-decane, and kerosene) oils were emulsified in water and the results were compared with the experimental ones. It has been concluded that the extended Taylor equation worked well, even in the presence of surfactant. The quality of the emulsion defined and discussed in terms of size and number of droplets was best near CMC of the surfactant used. A relationship has also been derived between CMC of surfactant and its distribution coefficient, which allows the exact value of one parameter to be determined if other is known.     

Hydration force due to the reduced screening of the electrostatic repulsion in few-nanometer-thick films

Experiments with foam films from solutions of 1 mM SDS + 100 mM electrolyte (LiCl, NaCl and CsCl) were carried out by a thin-film-pressure balance. The measured dependences of disjoining pressure versus film thickness exhibit a steep increase when the thickness of the film's water core becomes smaller than 3.7 nm. This behavior can be interpreted as a manifestation of the hydration force. We unsuccessfully tried to interpret the data with different available theoretical models. Eventually, we found that a relatively simple model of “reduced screening” can fit the data. Such reduced screening of the electric field could exist only in a narrow range of film thicknesses, which practically coincides with the region where the hydration repulsion is acting. This model and its experimental verification are described in the article.     

热处理对聚醚醚酮晶体结构参数及结晶度的影响

采用广角Ｘ射线衍射（ＷＡＸＤ）方法研究了不同热处理温度下聚醚醚酮（ＰＥＥＫ）的晶胞参数、微晶尺寸及结晶度的变化。根据Ｘ射线散射强度理论，运用图解多重峰方法导出了以ＷＡＸＤ方法计算ＰＥＥＫ结晶度的公式；用此公式对经不同热处理的ＰＥＥＫ样品进行计算，结果与由密度法及量热法测定的结果具有较好的可比性。     

Effect of the means of preparation of nanodispersed CuO/MgO catalysts on their activity in the oxidation of CO

A method is proposed for obtaining copper-containing catalysts by means of mechanical mixing of previously formed monodispersed CuO nanoparticles (mean particle diameter 12 nm) with MgO. Higher activity was found for these catalysts in the oxidation of carbon monoxide than for the analogous copper-containing systems prepared by impregnation and deposition of cupric oxide nanoparticles from colloidal solution. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 165–169, May–June, 2008.     

Pt/C催化剂对甲酸电催化氧化的粒径效应

在甲醇溶剂中,利用SnCl2作为还原剂,通过控制反应条件制备了具有不同粒径Pt粒子的炭载Pt(Pt/C)催化剂.X射线衍射(XRD)和透射电子显微镜(TEM)的结果表明,Pt/C催化剂中Pt粒子具有高度的均一性和良好的分散度.电化学研究结果显示,对于甲酸的电催化氧化,Pt/C催化剂存在着明显的粒径效应.当Pt粒子粒径为3.2 nm时,Pt/C催化剂对甲酸的电催化氧化活性最佳.Pt/C催化剂对甲酸氧化的粒径效应与其表面含氧基团含量、Pt粒子的比表面积及相对结晶度相关.     

Influence of particle size distribution on thermokinetics of ilmenite with sulphuric acid reaction

The knowledge about kinetics of the reaction titanium raw materials with sulphuric acid is very important from the reason of influence of initial conditions of reaction on efficiency, quality and safety. One of the very important parameter, which influence on kinetics of this reaction is distribution of particles sizes of raw material. Presented results of investigation of reaction thermokinetics of ilmenite with different particles sizes, obtained in special construction of calorimeter, demonstrated very great influence of this parameter on rate of reaction with sulphuric acid. On the base of experimental investigation the kinetic model of this reaction was elaborated which takes into account density of particles sizes distribution described by the function of Rosin–Rammler. Presented model was tested on the base of experimental data of ilmenite with sulphuric acid reaction.     

pH值对硅油乳液Zeta电位及其制备的影响

1994年,T．M．Obey和V．Brian采用二甲基二乙氧基硅烷在氨水催化剂下进行乳液聚合,获得了具有较好单分散性的聚二甲硅油乳液。本文研究了pH值对二甲基二乙氧基硅乳液Zeta电位的影响,比较了有相同单体浓度的单相体系在低pH值(酸性)和高pH值(碱性)条件下乳液聚合的规律,以期对硅烷乳液制备做更进一步的研究。     

Structural characteristics of different types of nanoparticles synthesised in mesomorphic metal alkanoates

The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC₈) and of the cobalt octanoate (CoC₈). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained.