Investigation On the Behavior of Poly(acrylic acid) in Water Solution and Its Effect on the Rheology of α- Al2O3 Suspension

The influence of pH, relative molecular weight and concentration of poly(acrylic acid) (PAA) on the viscosity of PAA solution was investigated. It was found that the rheology of PAA solution was closely related to the ionization and conformation of PAA chains. The increasing rigidity and the stretching of polymer chain resulted in a maximum viscosity at pH=8. The viscosity change of PAAsolution with addition of alumina powder was studied. It was found that the suspension viscosity reached its minimum when the amount of ceramic powder and PAA was at a certain ratio. At the same time, the viscosity minimum was also influenced by the particle size of powder.     

VISCOMETRIC INVESTIGATIONS OF POLYVINYLPYRROLIDONE IN MIXED SOLVENTS AND WITH VARYING TEMPERATURE

The viscosity behavior of polyvinylpyrrolidone (PVP) has been determined at 25℃ in mixed solvents comprising water/dimethylformamide (DMF) and water /methanol (MeOH). Analysis of the data has considered the PVP as being both host and guest polymer in solution. The intrinsic viscosity of PVP in DMF is higher than in water and in MeOH, but also increases in a mixed solvent with high water content because of the effect of polymer-solvent interactions. It was also found that the intrinsic viscosity of PVP at finite concentration, [ηpvp]c decreases with an increase in the concentration of PVP in solution. The viscosity behavior of PVP in a mixed solvent is affected by the concentration-dependent intermolecular excluded volume effect, which can be quantitatively expressed by the parameter, bY, which reflects the shrinkage of PVP chain coils, resulting in a decrease of [ηpvp]c. The effect of temperature on the viscosity behavior of PVP in MeOH shows that the interaction parameter increases up to a maximum value, and then decreases after a certain temperature.     

聚氧化乙烯水溶液粘度的测定

测定了不同分子量聚氧化乙烯(PEO)在水溶液中的粘度，发现在低浓度区高分子溶液比浓粘度出现负偏离。用高分子溶液流过时间对浓度作图的外推值t0^*重新计算相对粘度，则高分子溶液比浓粘度与浓度之间满足线性关系。不同分子量PEO水溶液流过时间对浓度作图的外推值t0^*是完全一致的。利用纯溶剂在粘度计中流过时间的改变确定了高分子在毛细管管壁上吸附层的厚度，发现PEO在毛细管管壁上吸附层厚度与分子量无关。     

Charge density dependence of solution and gel behaviors of maleic acid-containing polyelectrolytes

Two kinds of polyelectrolytes containing maleic acid component (MA copolymers), i.e., poly(styrene-alt-maleic acid) (PSMA) and poly(vinyl methyl ether-alt-maleic acid) (PVMEMA), were investigated on their polymer chain dimensional changes in solution, and also in gel phase for the latter, as a function of the polymer charge density or pH of the (immersing) solution. Being different from common poly(carboxylic acid)s such as poly(acrylic acid), both of the MA copolymers showed maximum in the reduced viscosity or the gel size with increasing the charge density or the solution pH. The maximum in the reduced viscosity was much more significant for PSMA than PVMEMA. To see if intramolecular hydrogen bond between a pair of dissociated and undissociated carboxyl groups in an MA residue contributes to the emergence of the peak or not, similar measurements were performed also in the presence of concentrated urea (5 M). Almost the same values were obtained up to the peak position for the reduced viscosity and the gel swelling degree with increasing pH of the (immersing) solutions, which strongly suggested that the supposed effect is negligible, if any. All the results including those for PVMEMA system were interpreted in terms of the ionomer-like conformational change (ion cluster formation) of polyelectrolytes that has been often observed when the polymer charges are in rather less polar circumstances.     

Stability of a model alkali-soluble associative polymer in the presence of a weak and a strong base

 Hydrophobically modified alkali-soluble emulsion (HASE) polymer is solubilized by the addition of a base. When the pH is increased to greater than 6.5, methacrylic acids on the polymer backbone are neutralized and the carboxylated latex polymer goes into solution causing a large increase in the viscosity due to inter-molecular associations of the hydrophobes. The stability of the viscosity of the polymer solution at pH in the range 9–10 was studied in the presence of a strong (NaOH) and a weak [1-amino-1-methylpropanol (AMP)] base. No change in the viscosity or the moduli was observed for the polymer in AMP. Reduction in the viscous and elastic properties of the polymer solution in NaOH was observed after 4 weeks. Such small changes are detectable using the superposition of oscillation on the steady shear technique. The decrease in the viscoelastic properties is attributed to the hydrolysis reaction of the urethane groups of the macromonomer, which resulted in a decrease in the number of hydrophobes per polymer chain. It is recommended that a weak base be used to neutralise the HASE polymer in order to avoid the possibility of compositional changes in the polymer after neutralisation for more than 6 weeks. Received: 19 May 1998 Accepted in revised form: 26 October 1998     

Water-soluble polymers. 71. pH responsive behavior of terpolymers of sodium acrylate,acrylamide, and the zwitterionic monomer 4-(2-acrylamido-2-methylpropanedimethylammonio)butanoate

Terpolymers of sodium acrylate (NaA), acrylamide (AM), and the zwitterionic monomer 4-(2-acrylamido-2-methylpropanedimethylammonio) butanoate (AMPDAB) were prepared by the free radical polymerization in 0.5M NaBr aqueous solution using potassium persulfate as the initiator. The feed ratio of AMPDAB : NaA : AM was varied from 5 : 5 : 90 to 40 : 40 : 20 mol %, with the total monomer concentration held constant at 0.45M. Terpolymer compositions were determined by ¹³C NMR. Molecular weights varied from 3.0 × 10⁵ to 9.7 × 10⁶ g/mol. All terpolymers were soluble in deionized water and salt solutions at all pH values. The dilute and semidilute solution behavior of the terpolymers was studied as a function of composition, pH, and added electrolytes. Polyelectrolyte behavior was observed for all terpolymers at pH 8.5, as evidenced by high viscosity values at low polymer concentrations and viscosity decrease in the presence of added electrolytes. The reduced viscosity as a function of decreasing pH exhibits a minimum as the terpolymer undergoes a polyanion/polyzwitterion/polycation transition. Comparison of the solution behavior of the terpolymers to terpolymers of 3-(2-acrylamido-2-methylpropane dimethylammonio)-1-propane sulfonate (AMPDAPS), AM, and NaA (AADAPS series) as well as copolymers of AMPDAB and AM (AMPDAB series) have been made. © 1997 John Wiley & Sons, Inc.     

Polymerization of pyromellitic dianhydride with 3,3′-diaminobenzidine in aprotic solvents II. Dilute solution studies

Solution properties were determined for the poly(amide acid amine) obtained from the room-temperature polymerization of pyromellitic dianhydride with 3,3,-diaminobenzidine in aprotic solvents. Membrane osmometry data, viscosity studies, solution aging studies, and pH–viscosity relationships were given. Anomalous upswings in viscosity–concentration plots were attributed to absorption or capillary wall effects and not to polyelectrolyte effects, such as were induced by addition of strong bases. Similar absorption effects were found with polyamic acid solutions, in contrast to earlier reports that these polyimide precursors were polyelectrolytes. Unfavorable storage characteristics of the polymer solutions were explained by aging studies which showed that at 25°C dilute solutions exhibited a rapid drop in viscosity; in concentrated solution a slow increase to gelation was observed.     

A viscosity self-oscillation of polymer solution induced by the Belousov-Zhabotinsky reaction under acid-free condition

We succeeded in measuring a viscosity self-oscillation induced by the Belousov-Zhabotinsky (BZ) reaction for a polymer solution on the constant temperature condition under acid-free condition. The polymer chain is consisted of N-isopropylacrylamide, ruthenium complex as a catalyst of the BZ reaction, and an acrylamide-2-methylpropanesulfonic acid (AMPS) as a pH and the solubility control site. The viscosity self-oscillation for the AMPS-containing polymer solution was attributed to the difference between viscosities for the polymer solution in the reduced and oxidized states. The effects of the polymer concentration and the temperature of the polymer solution on the viscosity self-oscillation were investigated. As a result, the viscosity self-oscillating behavior significantly depended on the polymer concentration and the temperature of the polymer solution. The period of the viscosity self-oscillation decreased with increasing temperature in accordance with the Arrenius equation.     

Viscosity-Temperature Behavior of Hydroxypropyl Cellulose Solution in Presence of an Electrolyte or a Surfactant: A Convenient Method to Determine the Cloud Point of Polymer Solutions

The viscosity of hydroxypropyl cellulose (HPC) solution with or without an additive has been measured continuously as a function of temperature with the help of a vibro-viscometer. The viscosity of the polymer solution showed a gradual decrease initially with increase in temperature until a particular point beyond which there was a sharp decrease in the viscosity, which coincided with the clouding of the solution. The cloud point temperature (CP) of the polymer solution was determined from the first derivative plot of viscosity vs. temperature. Effect of addition of an electrolyte or a surfactant on the CP of HPC solution has also been studied. While a decrease in CP of HPC solution in presence of fluoride, chloride, or bromide ions was observed, presence of iodide or thiocyanide ions led to an increase in the CP. However, presence of an ionic surfactant initially lowered the CP but beyond a particular surfactant concentration a sharp increase in cloud point was observed due to interaction of the surfactant with the polymer. The results suggest that surfactants with longer hydrophobic tail or more hydrophobic groups have more affinity for HPC.     

Rheological properties of polymer melts

A new method of treating experimental data on the viscous and viscoelastic properties of various polymer melts is suggested. The dependence of the apparent viscosity on the molecular weight, temperature and shear stress can be represented as the product of three independent functions, each of them having a single argument. All three functions are universal, at least in first approximation, and the dependence of the apparent viscosity on the variables indicated is determined by two parameters (glass transition temperature and critical molecular weight), characteristic of each homologous polymer series. The viscoelastic characteristics (dynamic, relaxation, creep, as well as relaxation and retardation spectra) of polymer melts are universal in shape in the linear region and contain only one individual polymer parameter, viz., maximum Newtonian viscosity. It is shown that upon normalization of certain nonlinear characteristics with respect to the maximum Newtonian viscosity, they can also be represented in the universal form.     

Asymmetric interaction of optically active polymers with asymmetric small molecules. III. The effect of pH on asymmetric interaction of optically active acidic polymer with tryptophan

The interaction of optically active polymer prepared from L-lysine and adipyl chloride by interfacial polycondensation with D - and L-tryptophan was studied. It was found that selective interaction occurred, and the amount of L-isomer bound to the polymer was greater than that of D -isomer in the range from pH 3.0 to 7.5 at 25°C. At near pH 5.0, the maximum asymmetrical ratio was obtained. The optical rotatory dispersion and viscosity of the polymer were measured. The relationship between conformational differences of the polymer and asymmetric interaction is discussed.     

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.     

亚铁离子对驱油聚合物溶液黏度的影响及其降黏机理

采用NaOH沉淀法去除胜坨油田T28区污水含有的亚铁离子(Fe2+),使配制的聚合物溶液黏度增加,通过红外光谱仪(IR)、荧光光谱仪及扫描电子显微镜(SEM)对Fe2+的降黏机理进行了分析。 结果表明,采用NaOH沉淀法处理Fe2+含量为5.9 mg/L的污水,控制pH=9,聚合物溶液的黏度可由19.17 mPa·s提高到92.50 mPa·s。 Fe2+使聚合物大分子发生断链,分子间的缔合作用减弱,破坏了分子链间形成的空间网络结构,导致溶液黏度显著降低;当用NaOH处理Fe2+后形成了Fe(OH)2沉淀而析出,同时使聚合物分子链间形成致密的空间网络结构。     

一种疏水缔合水溶性聚合物的合成及其溶液性能

粘度;抗盐性;表面活性剂;一种疏水缔合水溶性聚合物的合成及其溶液性能     

Diffusion coefficient and capacity factor in capillary electrokinetic chromatography with replaceable charged polymeric pseudophase

Apparent diffusion coefficients, Dapp,i, were determined in solutions with a polycationic additive -- poly(diallyidimethylammonium) -- acting as a pseudostationary phase for electrokinetic chromatography. They were determined for six small neutral analytes at five concentrations of the polymeric additive (between 0 and 4% w/w) by a stopped migration method. The apparent diffusion coefficients decrease with increasing polymer concentration only within 40% maximum, an effect that cannot be associated with the macroscopic viscosity of the polymer solution (which increases by a factor of 10). The change of the apparent diffusion coefficients is related to the interaction of the neutral analyte molecules with the polyelectrolyte chain. Applying the model of analyte partitioning between "free" solution and polymer, capacity factors and partition constants were derived from the slope of the 1/Dapp,i vs. polymer concentration curves. Partition constants determined by this method (ranging between 40 and 170) agree with those obtained by electrokinetic chromatography.     

Viscosity enhancement of complexed solutions formed through the complexation of nonionic water‐soluble polymers with chemically complementary structures in aqueous media

The intermacromolecular complexation of polymers with chemically complementary structures in aqueous media is a new approach to modifying polymer solutions, especially to enhance solution viscosity. In this study, complexed solutions formed through the hydrogen‐bonding complexation of several nonionic water‐soluble polymer pairs—poly(acrylic acid) (PAA) with polyacrylamide (PAM), PAM with poly(ethylene oxide) (PEO), PAA with poly(vinyl alcohol) (PVA), and PEO with PVA—were prepared, and the viscosity enhancement of the complexed solutions were studied with vision spectrophotometry and viscometry. The effects of the polymer concentration, polymer molecular weight, and pH value of the polymer solution on the intermacromolecular interactions were investigated through a comparison of the viscosity enhancement factor R of different complexed solutions. The results show that the viscosity of the PAA/PAM complexed solution is much higher than that of its constituents, whereas that of the PAM/PEO and the PAA/PVA complexed solutions are between the viscosities of their constituents but are higher than the theory values calculated from the blending rule of two polymer solutions. These results indicate that in the complexed solutions there exist interactions between the macromolecules with chemically complementary structures, although the interactions are quite different for the different complexed systems. It is the interactions that lead to an association of the polymers and, hence, an obvious enhancement in the solution viscosity and the resistance of the polymer solutions to shearing. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1069–1077, 2000     

Rheology of an aqueous solution of an end-capped poly(ethylene glycol) polymer at high concentration

Generally it is observed that the viscosity of an aqueous solution of a hydrophobically modified polymer increases with concentration; however, here it is shown that the viscosity profile of an end-capped poly(ethylene glycol) polymer passes through a maximum. Thus, a substantial decrease in viscosity is observed at high concentrations (≥50 wt%). The observation is suggested to be due to a gradual change, on the molecular level, from a structure containing micellelike structures that are interconnected via polymer bridges to a more meltlike state, where micro segregation in hydrophilic and hydrophobic regions is less pronounced. Received: 23 October 1998 Accepted in revised form: 10 March 1999     

Negative thixotropy of polymer solutions. 1. A model explaining time-dependent viscosity

Negative thixotropy, also called antithixotropy, is the effect of a flow-induced increase in viscosity that has been observed for many polymer solutions. Here, a simple quantitative model describing the time dependence of the shear stress or viscosity is presented. The model assumes a dynamic gel or network in the polymer solution, whose cross-links are dynamically formed and broken. The cross-links exist with or without deformation or flow of the solution. A second property of the model network is that it cannot be deformed infinitely, which is also true for any real network. The dynamic network solution is characterized by four parameters: its elastic shear modulus, its maximum degree of deformation, the rate with which the dynamic cross-links form and break and the viscous contribution of the polymer solution. The first two parameters can be related to each other, so only three independent parameters enter the model. An analytical solution is obtained which describes the flow-induced increase in viscosity, the minimum shear rate required for negative thixotropy and the dependence of the induction time on the shear rate. The results are shown to be in agreement with reported experimental results.     

粘度和光谱方法研究二元阴离子型丙烯酰胺共聚物(P3A)在不同pH水溶液中的构象变化

采用粘度和光谱方法,研究了强酸性和弱酸性2种阴离子型单体与丙烯酰胺的三元共聚物(P3A)在稀水溶液中pH诱发的构象变化,P3A聚合物由丙烯酰胺(AM)和强酸性离子单体(AMPS)及弱酸性离子单体(AA)组成.试验结果表明P3A聚合物溶液的粘度随pH呈现非单调的增长关系,在pH为4～5范围内产生急剧的升高,这现象归因于聚合物链团从紧密状态向膨胀状态迅速的转变.这两种状态的溶液粘度变化幅度和聚合物P3A中AMPS和AA组合比例紧密相关,芘探针在聚合物P3A溶液中的荧光强度和pH的关系呈现类似粘度变化的结果.在低pH值时,发现单一弱酸离子共聚物(P2AA)溶液发生相分离,然而在含有强酸单元(AMPS)的P3A聚合物情况下,这种现象不再产生.     

Local viscosity analysis of triblock copolymer micelle with cyanine dyes as a fluorescent probe

The local viscosity of Pluronic F127 triblock copolymer micelles in water was determined with cyanine dyes as fluorescent probes. These dyes show very weak fluorescence at a low temperature, but show enhanced fluorescence at a temperature higher than the critical micellization temperature (T(cm)). This is because a viscous environment within the micelle suppresses the formation of a nonradiative twisted intramolecular charge transfer (TICT) excited state of the dyes. The good correlation between the fluorescence quantum yields of the dyes and the viscosity and the temperature of the media allows a determination of local viscosity of micelle based on the fluorescence quantum yields. The local viscosity of both core and corona regions of micelles increases at >T(cm) and shows a maximum at a temperature 7-9 °C higher than T(cm), and decreases at higher temperature due to the increased fluidity. The core viscosity is larger than that of the corona, and the corona viscosity increases toward the micelle center. The polymer concentration has different effects on the core and corona viscosity: the corona viscosity increases with a polymer concentration increase at the entire temperature range, whereas the core viscosity increases only at a low temperature. The corona viscosity increase is due to the condensation of a large number of polyethylene oxide (PEO) blocks. In contrast, the dehydration degree of polypropylene oxide (PPO) blocks in the core scarcely changes, and the core has a similar composition regardless of polymer concentration. The larger polymer concentration promotes a micelle formation at lower temperature where the fluidity increase is very weak, resulting in larger core viscosity.