Sedimentation Kinetics of Bentonitic Clay Suspension as Influenced by pH of the Medium,Chemical Nature and Concentration of Surfactants,and Molecular Properties of Cationic Acrylamide Copolymer Flocculants

The kinetics of flocculation of bentonitic clay suspensions and thickening of the sediments was studied in the modes of free and hindered sedimentation as influenced by pH of the medium, chemical nature and concentration of surfactants, and molecular properties of cationic flocculants, random copolymers of acrylamide with dimethylaminoethyl methacrylate hydrochloride.     

Influence of Concentration and Molecular Characteristics of Copolymers of Acrylamide with Sodium Acrylate on the Thoms Effect in Oil-in-Water Emulsions

The effect of the concentration and molecular parameters of random copolymers of acrylamide and sodium acrylate on their performance as additives reducing the hydraulic resistance of turbulent flows in oil-in-water emulsions is quantitatively studied.     

Toms Effect in Direct Crude Oil Emulsions as Influenced by the Stream Velocity and Concentration of Anionic Copolymers of Acrylamide

The major relationships in the Toms effect in direct crude oil emulsions differing in the dispersed phase concentration were studied on a modified turbulent rheometer with anionic copolymer of acrylamide as the polymer additive. The Toms effect was studied as influenced by the polymeric additive concentration and shear stress.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 506–511.Original Russian Text Copyright © 2005 by Myagchenkov, Chichkanov, Yakovenko.     

Influence of the Concentration of Ionic Acrylamide Copolymers,Ionic Strength,and Kind of the Electrolyte on the Thoms Effect

The influence exerted by the copolymer concentration, ionic strength, and kind of single- and multicharged ions on the reduced Thoms effect was examined for ionic acrylamide copolymers as additives reduciong the hydraulic resistance of turbulent aqueous-salt flows. Synergism and antagonism were detected for certain combinations of the polymer and electrolytes.     

Effect of pH on the Behavior of a Random Copolymer of Acrylamide

A temperature- and pH-sensitive random copolymer of N-[3-(diethylamino)propyl]-N-methylacrylamide] and N,N-diethylacrylamide was obtained. The copolymer contained 20 mol % of amine units and had a molecular weight of 3.3 × 10⁴. Buffer solutions containing 0.0102 g/cm³ of the synthesized copolymer were studied in the pH range of 7–13.5 by light scattering and turbidimetry. At low temperatures, macromolecules and large aggregates coexist in the solutions. The copolymer is temperature- and pH-sensitive in the studied pH range. The temperature and the width of the phase separation interval increase with increasing acidity of the medium.     

水溶液中单电子转移活性自由基聚合法制备新型阳离子共聚丙烯酰胺/丙烯酸酯

以咪唑、丙烯腈和溴辛烷等为原料,合成了新型阳离子型可聚合离子液体表面活性剂单体：氯化-1-正辛基-3-（4-丙烯酸丁酯基）咪唑（PMOIH8）。 以2-氯丙酰胺为引发剂,Cu0粉/三-（2-二甲氨基乙基）-Me-6-TREN为催化体系,采用单电子转移活性自由基聚合法对丙烯酰胺（AM）、PMOIH8进行了二元共聚合反应,合成了一种新型阳离子共聚丙烯酰胺/丙烯酸酯P（AM/PMOIH）。 FT-IR、MS和1H NMR分析表明,所得聚合物为目标产物,采用GPC测得聚合物的相对分子质量为2×103~14×103,相对分子质量分布Mw/Mn在1.21~1.75之间。 考察了催化剂、引发剂等因素对聚合的影响。 结果表明,降低催化剂用量,聚合反应速率变慢,链增长速率常数kappp由0.0168 min-1降低至0.0065 min-1,Mw/Mn由1.25~1.71增加至1.32~1.75,引发效率Ieff=90.24%;增加引发剂用量,Mw/Mn由1.25~1.71减小至1.21~1.68,kappp由0.0168 min-1增加至0.0201 min-1,Ieff增加至93.17%。     

季铵盐阳离子单体对三元无皂乳液共聚物纳米球的影响

以偶氮二异丁基咪盐酸盐(AIBA)为引发剂,以苯乙烯(St)、丙烯酸丁酯(BA)、季铵盐型阳离子单体2-甲基丙烯酰氧乙基三甲基氯化铵(DMC)及对-乙烯基苄基三甲基氯化铵(VBT)为单体,采用无皂乳液聚合法于80℃恒温水浴、300r/min搅拌条件下,制备了三元共聚物阳离子纳米球P(St-BA-DMC)和P(St-BA-VBT)。通过透射电子显微镜(TEM)、激光粒度分析仪、差示扫描量热仪(DSC)等测试分析,讨论了季铵盐阳离子单体对纳米球结构和性质的影响。结果表明:纳米球P(St-BA-DMC)的粒径随DMC用量的增加先减小后增大,纳米球P(St-BA-VBT)的粒径随VBT用量的增多逐渐减小;阳离子纳米球的表面电荷密度、玻璃化转变温度随阳离子单体的增加而增加;两种阳离子单体分别参与的体系中都存在两种深浅不同的纳米球,原因可能是成核过程中形成的低聚物自由基的疏水性越大,体系中含PS链段较多的密度较大的纳米球所占比例就越大,而低聚物自由基疏水性越小,则体系中含PBA链段较多的密度较小的纳米球就越多。     

阳离子淀粉-壳聚糖-丙烯酰胺的接枝共聚研究

以硝酸铈铵为引发剂,合成阳离子淀粉(CS)-壳聚糖(CTS)-丙烯酰胺(AM)接枝共聚物,讨论了反应温度、引发剂浓度、单体用量、反应时间以及壳聚糖用量对接枝共聚反应的影响。结果表明:淀粉中葡萄糖环浓度(cAGU)为0.20 mol/L,mCTS/mCS=1/6,cAM=1.0mol/L,cCe4 =5 mmol/L,反应温度60℃,反应时间3 h时,转化率和接枝效率可分别达到88%和92%以上;转化率随mCTS/mCS增大而增大,接枝效率则随着CTS用量增大降低,CTS的存在使AM均聚的几率增大。     

Toms Effect as Influenced by the Glass Capillary Length and Diameter

The degree of reduction of the hydraulic resistance was studied as influenced by the concentration of the anionic copolymer of acrylamide, geometric parameters of the contour, and turbulent flow velocity.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 669–672.Original Russian Text Copyright © 2005 by Chichkanov, Myagchenkov.     

活性阳离子聚合法合成嵌段共聚物的研究进展

在８０年代,阳离子聚合研究的一个最重要突破可能就是活性阳离子聚合。目前为止,有关活性阳离子聚合的新引发体系,新单体及合成应用等方面已取得巨大进展,本综述主要介绍利用活性阳离子聚合合成二、三元嵌段和多元嵌段共聚物的研究成果。     

十二烷基磺酸钠对丙烯酰胺－烯丙基磺酸钠共聚物溶液粘度的影响

丙烯酞胺-烯丙基磺酸钠共聚物(PASA)优良的絮凝性能已在前文^[1]中报道.本文主要考察阴离子表面活性剂R₁₂SO₃Na对其溶液粘度的影响,并与PAM做了对照.     

Modelling of the Critical Micelle Concentration of Cationic Gemini Surfactants Using Molecular Connectivity Indices

Modelling of the critical micelle concentrations (cmc) using the molecular connectivity indices was performed for a set of 21 cationic gemini surfactants with medium-length spacers. The obtained model contains only the second-order Kier and Hall molecular connectivity index. It is suggested that the index ² χ includes some information about flexibility. The obtained model was used to predict log₁₀ cmc of other cationic gemini surfactants. The agreement between calculated and experimental values of log₁₀ cmc for the gemini surfactants that were not used in the correlation is very good.     

Superswelling of Hydrogels Based on the Copolymer of Acrylamide and Methacrylic Acid

Weakly crosslinked hydrogels of copolymers of acrylamide and methacrylic acid are synthesized by radical polymerization in aqueous solution in a wide range of comonomer ratios. It is found that gels containing 20–40 mol % methacrylic acid are characterized by superswelling that exceeds the degree of swelling of homopolymer hydrogels by tens of times. The observed degree of swelling reaches 830, corresponding to an almost completely stretched conformation of subchains between network junctions. For dried hydrogel samples, the equilibrium degree of swelling is also maximal in the mentioned composition range; however, its maximum value is lower than the equilibrium degree of swelling for the initial samples. The possible reason behind the superswelling of hydrogels containing 20–40% units of methacrylic acid is an increase in ionization of network subchains. This hypothesis is proved by an increased sensibility of hydrogels of this composition to a change in the pH of a medium and the lowest values of the effective acidity constant determined by potentiometric titration for methacrylic acid units. The values of partial heat capacity of a gel polymer network are determined by calorimetry. These values are significantly higher than the heat capacities typical of vinyl polymers. This is evidence that the hydrophobic type of hydration predominates in the copolymers of acrylamide and methacrylic acid. The partial heat capacity reaches its maximum within the copolymer composition range corresponding to superswelling.     

Copolymerization of Acrylamide with Salts of 2-Acrylamido-2-methylpropanesulfic Acid in Aqueous Solutions as Influenced by the Nature of Double-Charged Cation

The kinetics of copolymerization of acrylamide with magnesium, calcium, and strontium 2-acryl-amido-2-methylpropanesulfonates in aqueous solutions in the presence of potassium persulfate-sodium hydrosulfite initiating redox system at pH 9 and 50°C was studied as influenced by the cation nature.     

Synthesis and Characterization of Amphiphilic Block Copolymer by Block Copolymerization of Butadiene and Acrylamide using Macroazoinitiator

Abstract

Macroazoinitiator (MAI) was prepared from hydroxyl‐terminated polybutadiene (HTPB) and 4,4′‐azobis‐4‐cyanopentanoic acid by direct polycondensation in the presence of 1‐methyl‐2‐chloropyridinium iodide at room temperature. This MAI used for block copolymerization of AAm at 60°C gave the best results in chloroform but the formation of a crosslinked product could not be ruled out in dioxane. It was inferred that for production of a linear block copolymer, homogeneous reaction mixture was required.

The resulting products were characterized by spectral studies IR and NMR, viscosity measurements. Distinct phase segregation of hydrophobic and hydrophilic blocks was evident through DSC analysis.     

乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯共聚物的合成及性能研究

以乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯为共聚单体,采用自由基聚合法合成了具有水溶性和氧化还原活性的聚合物,并通过示差扫描量热法、傅里叶红外光谱、紫外-可见吸收光谱,及电化学方法对其玻璃化转变温度、化学组成、质子化作用及电化学性能进行了分析。实验结果表明该共聚物为乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯三元共聚物。该共聚物具有较好的水溶性和柔性,这些特点有利于提高修饰电极电子转移的效率,以及实现酶活性中心与电极之间的直接电子转移。共聚物中的甲基丙烯酸二甲氨基乙酯结构单元在近中性的溶液中可发生质子化作用,可与酶之间形成离子键从而有利于缩短酶活性中心与电极表面之间导电路径。共聚物的电化学性能表现出良好的氧化还原可逆性,且实现了共聚物与电极之间的可逆电子转移。另外该共聚物在溶液中的扩散系数较低,有利于提高修饰电极的稳定性。     

Determination of the Critical Micelle Concentration of Cationic Surfactants by Capillary Electrophoresis

The determination of the critical micelle concentration (CMC) of cationic surfactants by capillary electrophoresis was demonstrated. In this study, tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DoTAB) were selected as cationic surfactants and propazine was chosen as test solute. In the evolution of the effective electrophoretic mobility of propazine as a function of surfactant concentration, a dramatic change in slope at a particular concentration is a good indication of the CMC of this surfactant. The CMC values determined experimentally were further confirmed by a curve-fitting approach. Simulation of the electrophoretic mobility curves as a function of surfactant concentration in both micellar electrokinetic chromatography and capillary zone electrophoresis using cationic surfactants as an electrolyte modifier was performed for propazine, and the intersection of these two mobility curves allowed us to precisely predict the CMC of the surfactant. The CMC values determined for TTAB and DoTAB are 1.6 ± 0.1 and 11.0 ± 0.1 mM, respectively, in the case of an electrolytic solution consisting of 70 mM phosphate buffer at pH 6.0. Moreover, the applicability of the electroosmotic mobility as a parameter for the determination of the CMC was examined.     

Synthesis of Cationic and Ampholytic Starch Graft Acrylamide and their Aqueous Salt Absorption

Acrylamide was grafted onto starch using ceric(IV) ion as initiator. Starch–graft-polyacrylamide was then modified through Mannich reaction using formaldehyde and diethylamine to give poly(N, N′-[(diethylamino) methyl]-acrylamide). The modified-graft copolymer was quaternized using different reagents; methyl iodide, n-butylbromide, sodium chloroacetate and propane sultone to give cationic and ampholytic graft materials. The absorbing properties of the produced materials toward deionized water and aqueous salt solutions were investigated. Studies of the absorbing properties of polyampholytes have revealed that these materials do not shrink upon increasing salt concentration. Kinetics of swelling in deionized water is also discussed.