稀溶液粘度法研究聚合物之间混溶性

介绍了几种粘度法判据，并对溶液中高分子－高分子，高分子－溶剂分子间的相互作用对混合物溶液粘度的影响进行了较为深入的讨论。     

多分散高分子的稀溶液粘度-浓度依赖性

依据最近提出的关于单分散高分子的稀溶液粘度的团簇理论,对多分散高分子的稀溶液粘度的浓度依赖性进行了更新的理论分析。最后得到一个新的多分散高分子的稀溶液粘度与浓度的关系式。实验研究表明,该关系式是与实验数据相一致的。     

现代高分子物理课程系列漫谈:I.金兹堡判据

金兹堡判据是判定平均场理论有效性的重要准则.本文从一道典型的高分子物理课程课后习题出发,通过求解过程总结在平均场理论框架下如何构造金兹堡判据,并将该思路推广到不对称两组分高分子共混物体系以及高分子溶液体系.     

离分子混合物溶液在极稀浓度区的粘度异常行为

上世纪50年代初人们就发现,高分子溶液的粘度在极稀浓度区往往表现出异常行为,即当浓度低于某一特定值后,比浓增比粘度浓度图偏离预计的线性关系,出现上弯或下弯的曲线.几十年来人们对此现象展开了大量研究,提出了一些互不协同的解释[1,2].最近,程时等[3,4]对该问题作了系统深入的研究,指出这种粘度异常是源于粘度测量中高分子溶液与毛细管内壁间的界面作用,并给出了消除界面作用干扰的理论改正公式.至此,单一高分子溶液粘度的异常问题得到了明确的解释.但是,关于高分子混合物在极稀浓度区的粘度行为的研究就比较稀少.80年代Ｄｏｎｄｏｓ…     

树状高分子的特性粘数与代数的关系

从爱因斯坦的粘度理论出发 ,联系树状高分子的分子结构参数 ,计算了树状高分子的特性粘数 ,得到了树状高分子的特性粘数与代数的内在关系 ,分析了树状高分子特性粘数特异行为的内在原因 ,使得对树状高分子特性粘数的理论预测成为可能     

树状高分子溶液在粘度计毛细管表面的吸附现象

本文测定了树状高分子DAB(PA) n 水溶液和脂肪族超支化聚酯及其硅烷化衍生物溶液性质 .通过粘度测量 ,得到了吸附常数k ,半数吸附浓度ca,分子间缔合常数Km ,特性粘度 [η]等参数 ,解释了特性粘度的反常行为 ,重点研究了吸附现象 .发现树状高分子和超支化高分子溶液在粘度计毛细管表面形成了多层吸附 ,高分子之间的相互作用及高分子与溶剂分子间的氢键作用是形成多层吸附的重要原因     

现代高分子物理课程系列漫谈:Ⅰ.金兹堡判据

金兹堡判据是判定平均场理论有效性的重要准则。本文从一道典型的高分子物理课程课后习题出发,通过求解过程总结在平均场理论框架下如何构造金兹堡判据,并将该思路推广到不对称两组分高分子共混物体系以及高分子溶液体系。     

聚酰胺-胺型树枝状高分子PAMAM溶液的特性粘度

测定了树枝状高分子PAMAM(聚酰胺-胺型,乙二胺为内核)及其季铵盐在水溶液中的特性粘度[η].结果表明,PAMAM的[η]在代数G=2～3处有最大值,而其季铵盐则在此处有最小值.同时发现高分子的流体力学等效圆球半径R_η随G增大近似线性增长.通过对PAMAM及其季铵盐特性粘度的研究,揭示了不同代数高分子结构形态的变化规律.     

粘度法研究氯化聚丙烯和涂料树脂间的相容性

用稀溶液粘度法研究了氯化聚丙烯与石油树脂、丙烯酸树脂和醇酸树脂间的相容性,并用α判据对相容性结果进行判别。结果显示,石油树脂/氯化聚丙烯的共混体系是相容的;丙烯酸树脂/氯化聚丙烯的共混体系是不相容的。而醇酸树脂与氯化聚丙烯的相容性情况复杂,由二者的组成决定。当m(醇酸树脂)∶m(氯化聚丙烯)1∶1时,体系是相容的;当m(醇酸树脂)∶m(氯化聚丙烯)1∶1时,体系是不相容的。通过共溶剂法和涂膜宏观特性对上述体系的相容性进行测定,所得结果与α判据的结果相符合,印证了稀溶液粘度法研究溶液中高分子间的相互作用来预测涂料树脂的相容性具有一定可行性。     

高分子稀溶液粘度的浓度依赖性

综述了高分子稀溶液粘度浓度依赖性的物理起源问题。对原有理论的不足作了分析,并论述了新近出现的团簇理论对理解此问题所作出的贡献。     

A new viscometric criterion for polymer-polymer interaction

Based on a simple cluster theory recently proposed for the viscosity of polymer dilute solution, a new viscometrical criterion was suggested to probe the interaction between unlike polymers. The new criterion was applied into some polymer mixture solutions to study the polymer-polymer interactions. It was found the new criterion is more reasonable.     

New dendronized polymers from acrylate Behera amine and their ability to produce visco-elastic structured fluids when mixed with CTAT worm-like micelles

Two new water soluble dendronized polymers (PLn) from acrylate Behera amine monomer of different molecular weights were successfully synthesized. The polymers were characterized by FTIR, NMR, GPC and DLS. Both GPC and DLS results indicated that these PLn have a remarkable tendency to form aggregates in solution that lead to apparent molecular weights that are much higher than their theoretical values, as well as large diameters in solution. However, the addition of any PLn to water did not cause any increase in viscosity up to concentrations of 1000 ppm. The possible interactions of PLn with the cationic surfactant CTAT were explored by solution rheometry. A synergistic viscosity enhancement was found by adding small amounts of dendronized PLn polymers to a CTAT solution composed of entangled worm-like micelles. The highest association tendency with CTAT was found for PL1 at the maximum polymer concentration before phase separation (i.e., 100 ppm). The solution viscosity at low-shear rates could be increased by an order of magnitude upon addition of 100 ppm of PL1 to a 20mM CTAT solution. For this mixture, the fluid obtained was highly structured and exhibited only shear thinning behavior from the smallest shear rates employed. These PL1/CTAT mixtures exhibited an improved elastic character (as determined by dynamic rheometry) that translated in a much longer value of the cross-over relaxation time and a pronounced thixotropic behavior which are indicative of a strong intermolecular interaction. In the case of the polymer with a higher theoretical molecular weight, PL2, its association with CTAT leads to an extraordinary doubling of solution viscosity with just 0.25 ppm polymer addition to a 20mM CTAT solution. However, such synergistic viscosity enhancement saturated at rather low concentrations (25 ppm) indicating an apparent lower solubility as compared to PL1, a fact that may be related to its higher molecular weight.     

Light scattering characterization of thermodynamic interaction of polymers in dilute solution. Effect of experimental error and temperature

Interaction between non-identical polymer molecules in a dilute solution of a mixture of two polymers is quantitatively characterized by the interaction parameter A₂₄, which is the second virial coefficient for interaction of unlike species. The value of A₂₄ may be experimentally obtained by light scattering. The determination of A₂₄ is very sensitive to experimental error in the input data, particularly for mixtures in which one polymer is greatly in excess, and for mixtures of polymers having molecular weights differing by orders of magnitude. A slight rise in A₂₄ with temperature has been observed for solutions of mixtures of polystyrene and poly(methyl methacrylate) in diethyl malonate in the range 25–100 C. This change in A₂₄ reflects the increased mutual miscibility of the polymers in solution at elevated temperatures.     

Light scattering characterization of thermodynamic interaction of polymers in dilute solution. Effect of solvent and molecular weight

Interaction of nonidentical polymer molecules in a dilute solution of a mixture of two polymers is quantitatively characterized by A₂₄, the second virial coefficient for interaction of unlike species. This parameter is related to the compatibility of the two polymers in solution and is obtainable experimentally, e.g., by light scattering. With chemically markedly different polymers, A₂₄ depends neither on the molecular weight of the polymers nor on the solvent and becomes characteristic of the polymer pair. For a mixture of two copolymers or of a homopolymer and a copolymer with similar compositions, A₂₄ depends both on the solvent and on the molecular weight of polymers. Under such circumstances A₂₄ ceases to be a quantity given only by the chemical structure of the two polymers; however, under suitable conditions it remains a sensitive function of the difference between the chemical nature of polymer components.     

Association of poly-N-[tris(hydroxymethyl)methyl] acrylamide with a water soluble β-cyclodextrin polymer

An acrylic polymer with pendent adamantyl groups was synthesized and its properties in an aqueous solution with a β-cyclodextrin (βCD) epichlorhydrin polymer examined. Viscosity properties of precursor and modified polymers show differences at low concentrations, but not at higher concentration probably due to very important hydrogen bonds which prevent the formation of intermolecular hydrophobic bonds. The association of both complementary polymers through the inclusion of adamantyl groups is evidenced by phases separation occurrence. Phase diagrams were established at two different concentrations of polymers. We have shown a maximal association of both polymers at these two concentrations, for the same ratio βCD moles/adamantyl groups: 2.4. Salt addition favors this association and displaces the two phases zone to smaller concentrations of modified polymer. Further, 4-nitrophenol can be extracted by the concentrated phase resulting from mixture of solutions of guest and host polymers, pointing out the availability of the associated phase to trap organic molecules.     

Amphoteric hydrophobic associative polymer: I synthesis, solution properties and effect on solution properties of surfactant

Using acrylamide, acrylic acid and octadecyl dimethyl allyl ammonium chloride as monomers, a kind of amphoteric hydrophobic associative polymer was prepared by solution polymerization. The polymer’s molecular weight is from 0.71 to 1.46 × 10⁶ g/mol. And the hydrolysis degree of the polymer is about 14.5%. The polymer solution exhibits good association interaction, and the higher the hydrophobic group content is, the stronger the association interaction is. The adding of the polymer makes the surface tension curves of the mixture solution deviate from the parent solution curve. Both the hydrophobic group content and polymer solution’s concentration exaggerate the deviation with their self-quantity increase. There exist an interaction between the polymer and surfactant, which almost has no direct relationship with the surfactant charge. The major interaction could be a hydrophobic association interaction.     

Research on association between multi-sticker amphiphilic polymer and water-soluble β-cyclodextrin polymer

The host cyclodextrin polymer-P(AM/A-β-CD/NaA) is prepared by redox free-radical copolymerization. Additionally, the multi-sticker amphiphilic polymer-P(AM/BHAM/NaA) as a guest polymer is synthesized using micellar polymerization. The copolymer structures are characterized by ¹H NMR. Subsequently, all the polymers and inclusion complexes are evaluated in terms of apparent viscosity, optical absorption spectra and rheological property. The results indicate that the inclusion association between the cyclodextrin group (CD) and multi-sticker hydrophobic monomer (BHAM) is in accordance with ternary interaction (CD/BHAM?=?2:1). Because of the inclusion association between the host and guest polymers, the solution of inclusion complex has much higher viscoelasticity even under the low amphiphilic polymer concentration. When the molar ratio of CD to BHAM is 1:1, the critical aggregation concentration (CAC) of the inclusion complex solution still remains. Furthermore, above the CAC, two types of associations, inclusion association and inter-molecular hydrophobic association, can occur in the complex solution and these interactions were also verified by fluorescence spectroscopy and atomic force microscopy (AFM). In this paper, the inclusion rule of cyclodextrin polymer with the multi-sticker amphiphilic polymer is discussed, and the rule of the enhanced solution viscosity is further explored.     

示差折光和光散射双检测体积排除色谱的绝对定量化

讨论了示差折光和光散射联用双检测体积排除色谱的绝对定量化的原理,强调指出了试样注入量在数据处理中的重要作用.测量注入试样的这两种检测器的检测常数,可以同时得到试样的折光指数增量和重均分子量的绝对值.这一方法除了适用于各种均聚物外,还可以应用于高分子混合物的分析.此时,如将混合物看作为单一溶质,从所得折光指数增量和重均分子量,可对它们的组成作出定量分析,还可以判断共混物两个组分之间有无分子缔合等现象的产生.这一方法应用于聚甲基丙烯酸甲酯/聚苯乙烯(PMMA/PS)混合物的溶液,指明在四氢呋喃中两者产生缔合而形成了复合物.     

Synthesis and characterization of a series of modified polyacrylamide

We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by 10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more promising application in enhanced oil recovery.     

Mutual selective exclusion of unlike polymers in dilute solution and its measurement by light scattering

The interaction of unlike polymer molecules (components 2 and 4) in a ternary solution can be regarded as selective exclusion or desorption of one polymer by another. A relation is derived between the coefficient of selective sorption and the interaction parameters A₂₄ and A₂₄₄ which are analogs of the second and third virial coefficients. The ratio between the apparent light-scattering molecular weight and the true value for a polymer solute in a ternary system with one component of a binary solvent polymeric is more involved than in a ternary system in which both solvent components are of low molecular weight. Under certain conditions, the introduction of polymer component 2 into a dilute solution of polymer component 4 may lead to a decrease in the total intensity of scattered light.