Polymer Saturation Point Research Articles

SYNERGISTIC EFFECTS OF ANIONIC SURFACTANT AND NONIONIC POLYMER ADDITIVES ON DRAG REDUCTION

Turbulent drag reduction (DR) behavior of mixed nonionic polymer and anionic surfactant solutions in water was studied in a pipeline set up to explore the synergic effects of mixed additives on DR. The concentration of polymer polyethylene oxide (PEO) was varied from 0 to 2000 ppm and the concentration of surfactant sodium dodecyl sulfate (SDS) was varied from 0 to 5000 ppm. The critical aggregation concentration (CAC), where the interaction between the polymer and the surfactant begins, and the polymer saturation point (PSP), where the polymer molecules become saturated with the surfactant, were determined using electrical conductivity and surface tension measurements. As the polymer concentration was increased the CAC decreased but the PSP increased. The relative viscosity showed a remarkable increase upon the addition of surfactant to the polymer solution due to extension of polymer chains caused by the formation of micelles on the backbone of the polymer molecules. The data exhibited a considerable increase in DR in the case of mixed polymer/surfactant systems. The percent reduction in friction factor was as high as 79 when 3000 ppm or more surfactant was added to the 500 ppm polymer solution. Furthermore, the drag reduction behavior of the polymer solution changed from so-called Type A to Type B. In Type A drag reduction, a transition from laminar to turbulent regime is observed with a clear-cut onset point. In Type B drag reduction, no transition or onset point is observed; the data fall on a gradual extension of the laminar line.

Vapor pressure osmometry, volumetry and conductometry investigations on the interaction of sodium dodecyl sulfate with poly(ethylene glycol) and poly(propylene glycol) in aqueous solutions

Micellar and thermodynamic properties of sodium dodecyl sulfate (SDS) in aqueous solutions of polyethylene glycol (PEG) (Mw=400, 2000, 6000 and 10,000gmol−1) and polypropylene glycol (PPG) (Mw=400gmol−1) were determined employing vapor pressure osmometry (VPO), volumetry, compressibility and conductometry techniques at different temperatures. The binding of SDS in aqueous solution with PEG and PPG was investigated by comparison of the thermodynamic properties of aqueous solutions of SDS in the absence and presence of PEG and PPG. In aqueous solutions, SDS does not bind to PEG400 chains however it binds to PPG400, PEG2000, PEG6000 and PEG10000 chains. The plots of water activity, specific conductivity, sound velocity and isentropic compressibility against surfactant concentration for aqueous SDS+polymer (PPG400, PEG2000, PEG6000 and PEG10000) solutions show two break-points: critical aggregation concentration (CAC) and polymer saturation point (C2).

Interaction of biocompatible polymers with amphiphilic phenothiazine drug chlorpromazine hydrochloride

Interaction of chlorpromazine hydrochloride (CPZ), an amphiphilic drug of phenothiazine category, was investigated with several biocompatible polymers. The studies were carried out by using conductometry. Results were found to be in analogy with the surfactant–polymer interactions. The plots of specific conductivity versus concentration of drug were nonlinear with three different linear regions and with two clear breaks. First break point is regarded as the onset of aggregation, i.e., critical aggregation concentration (C1) and appeared well below the critical micelle concentration of pure drug. Second break (C2) is regarded as polymer saturation point which is akin to the critical micelle concentration. At C2 polymer domain saturated with the drug monomers which occurred at quite higher concentration suggestive of unavailability of drug monomers at lower concentrations due to the polymer–drug binding. Free energies of aggregation (∆Gagg) and micellization (∆Gmic) were calculated with the help of degrees of micelle ionization obtained from the specific conductivity–[CPZ] plots.

Micellar parameters of diblock copolymers and their interactions with ionic surfactants

The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene) (E39B18) with anionic surfactant sodium dodecyl sulphate (SDS) and cationic surfactant hexadecyltrimethylammonium bromide (CTAB) were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration (CMC) and thereby the free energy of micellization (ΔGmic), free energy of adsorption (ΔGads), surface excess concentration (Γ) and minimum area per molecule (A). Conductivity measurements were used to determine the critical micelle concentration (CMC), critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization (α) and counter ion binding (β). Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks (I1/I3) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number (N), number of binding sites (n) and free energy of binding (ΔGb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.

Effect of polymer–surfactant structure on its solution viscosity

AbstractPolymer–surfactant interactions in solutions are important in wide range of applications. The interactions lead to the formation of various polymer–surfactant structures. The solution viscosity is dependent on the structure. Here we have studied the dependence of viscosity and structure on the composition of polymer–surfactant mixture. We have used non‐ionic polymer polyvinyl pyrrolidone (PVP) and negatively charged surfactant sodium dodecyl sulfate (SDS). PVP behaves as a negatively charged polyelectrolyte in pure water at pH 7.4. It interacts with SDS through hydrophobic interaction. This leads to the polymer saturation point (PSP). PVP behaves as a positively charged polyelectrolyte at pH 2.4. The SDS neutralizes the opposite charge of polymer. After the neutralization point of PVP, excess SDS interacts with the polymer through hydrophobic interaction. From the data of charge neutralization, charge on the polymer is calculated. From the data of PSP on PVP at various concentrations, we calculated the number of SDS molecules per PVP molecule. The structure of PVP–SDS complexes is observed by using transmission electron microscope at room temperature. The viscosity data are explained from the observed structure of PVP–SDS mixture. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Solution Properties of a Polymer-Nonionic Surfactant Mixed System

The cooperative binding behavior of progressively hydrolyzed polyacrylamide with nonionic surfactant TritonX-100 (Tx-100) at different concentrations and temperatures has been studied viscometrically. The effect of polymer concentration and temperature on association characteristics of surfactant molecules has been investigated tensiometrically. Rationalization of the results (intrinsic viscosity, polymer saturation point, critical aggregation concentration, etc.) in terms of surfactant and polymer concentration as well as temperature has been attempted.

Tensiometric investigation of the interaction and phase separation in a polymer mixture-ionic surfactant ternary system

The interaction and phase separation in a ternary mixture composed of hydroxypropyl methyl cellulose (HPMC), sodium carboxymethyl cellulose (NaCMC), and sodium dodecylsulfate (SDS) were investigated by tensiometry. Surface tension measurements of binary mixtures (0.7 % HPMC and 0.00-2.00 % SDS) and of ternary mixtures (0.7 % HPMC, 0.3 % NaCMC, and 0.00-2.00 % SDS) were performed. The measurements indicated interaction between HPMC and SDS, which resulted in HPMC-SDS complex formation. The critical association concentration, CAC, and polymer saturation point, PSP, were determined. Phase separation of ternary HPMC/SDS/NaCMC mixtures occurs at SDS concentration > CAC, i.e., when the HPMC-SDS complex is formed. The volume of the coacervate increases with increasing SDS concentration, and at SDS concentrations >1.00 %, the coacervate vanishes. The surface tensions (?) of ternary HPMC/SDS/NaCMC mixtures in the precoacervation region and at the onset of the coacervation region are similar to the ? of the corresponding binary HPMC-SDS mixtures, while in the coacervation and post coacervation region, they are close to the ? of the corresponding SDS solutions.

Study of Micellization Behavior of Some Alkyldimethylbenzyl Ammonium Chloride Surfactants in the Presence of Polymers

The micellization behavior of homologous series of cationic surfactants tetradecyl- (C14BCl), hexadecyl- (C16BCl) and stearyldimethyl-benzyl ammonium chloride (C18BCl) in water and in aqueous solutions of polymers such as polyvinyl pyrrolidone (PVP) and polyethylene glycols (PEG-20 and PEG-06) has been studied at 298.15 K using the conductometric method. The same method has also been used to study the mixed systems, that is, C16-C14BCl, C18-C16BCl, and C18-C14BCl over the whole mole fraction range of the higher chain length surfactant at 298.15, 308.15, and 318.15 K in water and in presence of 0.5 and 1.0% PVP by volume at 298.15 K. From these measurements various micellar parameters like critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization (ψ), and standard free energy of transfer () have been calculated. The CAC and values were found to decrease with increase in polymer concentration whereas PSP values were found to remain constant except in the case of C14BCl where PSP values were found to increase with polymer concentration. The regular solution approach has been applied to determine the mixed micelle mole fraction (X) and the interaction parameter (β). These parameters have also been discussed in terms of micelle-polymer interactions. The combination C16-C14BCl shows synergism at all the studied temperatures in aqueous solution whereas remaining combinations show antagonism (except for C18-C16BCl at 318.15 K). In presence of PVP, the binary mixtures show antagonistic behavior which increases with increase in PVP concentration.

Gemini Surfactant−Protein Interactions: Effect of pH, Temperature, and Surfactant Stereochemistry

The interactions between bovine serum albumin (BSA) and gemini surfactants derived from cystine have been investigated and were compared with the conventional single-chain surfactant derived from cysteine. The influence of the stereochemistry of the gemini surfactant on its behavior toward BSA was also investigated, as well as the effects of pH and temperature. Electrical conductivity and surface tension measurements were used to obtain important system parameters such as critical aggregation concentration (cac), polymer saturation point (psp), degree of ionization (alpha), and the amount of surfactant binding to protein (M). Stereochemistry was found to influence the surface properties of the surfactants studied and their interaction with BSA but not their micellar properties in solution.

Interaction between aqueous solutions of polymer and surfactant and its effect on physicochemical properties

AbstractInteraction between water‐soluble polymers and anionic surfactants has been studied by surface tension and conductivity measurements. Sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) were used as surfactant while polyacrylamide (PAA), commercial grade partially hydrolyzed polyacrylamide (PHPA), and xanthan gum were used as water‐soluble polymers for the present study. The behavior of surfactant–polymer interaction was found to be dependent on both surfactant and polymer concentrations. After the critical aggregation concentration (CAC), interaction between the water‐soluble polymer and surfactants was started and above the polymer saturation point (PSP) polymer was saturated by surfactant with no further change of surface tension and conductivity of the solution. It has also been found that alkali (NaOH) and salts (Na2CO3, NaCl) have significant influence on the polymer–surfactant interaction. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.

Investigation on the Interaction between Sodium Dodecyl Sulfate and Polyethylene Glycol by Electron Spin Resonance, Ultraviolet Spectrum, and Viscosity

The hydrophobically modified nitroxide radical molecule 2,4-dinitrophenylhydrazone of 2,2,6,6-tetramethyl-4-piperidind-1-oxyl (DNPHTEMPO) was synthesized and used as electron spin resonance (ESR) and a UV probe to investigate the interaction between sodium dodecyl sulfate (SDS) and poly(ethylene glycol) (PEG). The ESR results showed that the headgroups of SDS adsorbed on PEG were more tightly packed than those of the unperturbed micelles and a more compact structure was formed at the binding site of the polymer−micelle aggregate due to a strong decrease of the viscosity at the micelle−polymer interface. The nitroxide group of DNPHTEMPO consisted of ∼55 % water and ∼45 % hydrocarbon. The two breakpoints of the SDS + PEG system critical aggregation concentration (cac) and polymer saturation point (PSP) were obtained from the maximum absorption bands λmax at room temperature and the viscosity measurement at different temperatures. The average location of 2,4-dinitrophenylhydrazone in the micelle consisted of an environment containing approximately 90 % water and 10 % hydrocarbon. The η/Cp (viscosity/PEG concentration) decreased with the increase of PEG concentration and temperature and exhibited a polyelectrolyte character. The electroviscosity effect increased with increasing SDS concentration. The PEG concentration had little effect on the cac of the SDS + PEG system.

Thermodynamic study of polymersurfactant interaction in aqueous system

The critical micellar concentrations (CMC) of sodium dedecyl sulfate (SDS) in aqueous poly(vinyl pyrrodine) (PVP) (M.W. 40000) solutions have been determined at different temperatures. The CMC of SDS increases with increase in concentration of PVP and decrease with increase of temperature. The critical aggregation concentration (CAC) and polymer saturation point (PSP) decrease with increase in temperature. The effect of the increase in polymer concentration of CAC and PSP has been determined. The thermodynamic quantities associated with the PSP are computed.

Influence of hydroxypropylmethyl cellulose–sodium dodecylsulfate interaction on the solution conductivity and viscosity and emulsion stability

The conductivity, viscosity and rheological measurements were used to study the interaction of HPMC with an anionic surfactant-sodium dodecylsulfate (SDS) in aqueous solutions of different concentrations. The properties of HPMC solutions (0.1–1.0%) with increasing SDS concentrations (0–2.0%) were investigated. On the basis of following the changes of the system during the HPMC–SDS interaction, the characteristic concentrations of SDS at which interaction starts (the critical aggregation concentration (CAC)) and at which it ends (polymer saturation point (PSP)), were determined, and an interaction mechanism was proposed. The linear relationship between the PSP and HPMC concentrations was found, while CAC remained constant. To show that the interaction of the components in the continuous phase of dispersed systems can change their properties, the changes of stability of HPMC-stabilized oil-in-water emulsions with SDS addition were also examined. It was found that stability of the emulsions was influenced by the HPMC–SDS interaction. After the preparation, stability of emulsions increased with increase in continuous phase viscosity and stability changed with time according to the mechanism of HPMC–SDS interaction in the continuous phase.

Influence of hydroxypropylmethyl cellulose-sodium laurylsulfate interaction on rheological properties of the solution

Interactions between the polymers and surfactants in solution have widely been investigated because of their scientific and technological importance. These interactions can be utilized to modify the physicochemical properties of system in many food products, pharmaceutical formulations, personal care products, paints, pesticides, etc. Interaction between nonionic polymer - hydroxypropylmethyl cellulose (HPMC) and anionic surfactant - sodium laurylsulfate (SDS) in solution has been investigated in this paper by rheological measurements. Rheological measurements are performed by rotational viscometer at 20?C and changes of rheological characteristics of HPMC solutions (0.5-1.5%) with increasing SDS concentrations (0-4.0%) were determined. The results of these investigations showed that viscosity of the solution is dependant on HPMC-SDS interaction. At particular SDS concentration viscosity increases, reach maximum and after that decreases until reach constant value. From the viscosity changes the characteristic concentrations of SDS, critical aggregation concentration (cac) and polymer saturation point (psp), were determined. These concentrations are in linear relationships with HPMC concentrations. Rheological properties of the solution are strong influenced by HPMC-SDS interaction and exhibits more or less pronounced pseudoplastic behavior, which changes to Newtonian one after the psp has been reached.

The Role of the Carboxylate Head Group in the Interaction of Sodium Dodecanoate with Poly(ethylene oxide) Investigated by Electrical Conductivity, Viscosity, and Aggregation Number Measurements

The binding of sodium dodecanoate (SDoD) to poly(ethylene oxide) (PEO) in aqueous solution was investigated and compared with the well-known polymer–surfactant complexes formed between PEO and sodium dodecyl sulfate (SDS). Electrical conductivity measurements indicated that the concentration ratio of bound SDoD to PEO (on monomer basis) was greater than that for the system PEO–SDS. However, the aggregation numbers of the micelles supported on the polymer chain are practically constant and similar for both surfactants at concentrations lower than the polymer saturation point. The difference in binding capability is explained in terms of a larger PEO coil expansion upon complexation of SDoD than in the case of SDS. An increase in the polymer surface favors the binding of SDoD to PEO in aqueous solution. This conclusion is supported by the results of the viscometric studies of PEO–surfactant solution.

Effect of polymer and temperature on the critical micellar concentration of aqueous sodium dodecyl sulfate

The critical micellar concentrations (cmc) of SDS in aqueous polyethylene glycol (M.W. 35000) solutions have been determined at different temperatures. The cmc of SDS increases with the increase in concentration of PEG and decreases with increase of temperature. The critical aggregation concentration (CAC) and polymer saturation point (PSP) decrease with increase in temperature. The effect of the increase in polymer concentration of CAC and PSP has been determined. The thermodynamic quantities associated with the PSP are computed. Intrinsic viscosity [η] of the PEG increases with increase in SDS concentration.

Interactions between Poly(ethylene Oxide) and Sodium Dodecyl Sulfate in Elongational Flows

This work investigates the elongational flow of aqueous solutions of mixtures of a high-molecular-weight poly(ethylene oxide) (PEO) and sodium dodecyl sulfate (SDS). The formation of micellar aggregates of SDS along the PEO chain results in an increase in the strength of the extension thickening of the PEO solutions. This is especially pronounced under conditions in which the PEO molecules form transient entanglements in the flow field. The minimum PEO concentration required to form intermolecular entanglements is substantially reduced in the presence of micellar aggregates. This effect becomes quantitatively less important in solutions with NaCl, which suggests PEO coil contraction due to electrostatic screening of micellar aggregates. However, once extension thickening starts in the presence of NaCl, the growth of pressure drop is more abrupt than without salt, which suggests stronger interactions between PEO coils with attached aggregates. The critical aggregation concentrations of PEO/SDS and PEO/SDS/NaCl solutions agree with those reported in the literature, which were obtained by means of different experimental techniques. However, the saturation of the surfactant effect is attained at lower surfactant concentrations than the polymer saturation point previously reported. This might reflect a low sensitivity of the extension thickening effect to the amount of surfactant bound to the polymerchain as the saturation point is approached.

KINETIC EFFECTS OF SURFACTANT / POLYMER MIXTURES UPON ACIDIC HYDROLYSIS OF HYDROXAMIC ACIDS

ABSTRACT The influence of surfactant / polymer (polyethylene glycol, PEG, mol. wt. = 400) mixtures upon the acidic hydrolysis of two N-substituted hydroxamic acids, i.e., R(CO). N(OH)R' : R = C6H5, R' = C6H5;4-CH3C6H4 has been studied using cationic (CTAB, TTAB and CPC) and nonionic (TX-100 and Brij-35) surfactants. An inhibitory effect was observed. The results have been explained by Porinoy - Menger model. The critical aggregation concentration and polymer saturation point of the corresponding systems have also been measured with the conductivity and surface tension methods.

Interactions of anionic surfactants with poly(ethylene oxide) and bovine serum albumin polymers: effect of the counterion hydrophobicity

The interactions and properties of resulting complexes between poly(ethylene oxide) (PEO) and surfactants with different head groups, such as sulfates, carboxylate and phosphate has been investigated. Also investigated was the effect of counterion for PEO-dodecyl sulfate surfactants with lithium (LDS), sodium (SDS), cesium (CDS) and tetramethylammonium (TMADS). Special attention was given to the hydrophobic effect of the counterion TMA + on the binding. Studies were extended to bovine serum albumin (BSA)–dodecyl sulfate surfactant systems which were then compared with the conventional behavior of the PEO–SDS system. Electrical conductance measurements were used in order to characterize changes of parameters such as the critical aggregation concentration (cac), polymer saturation point (psp), degree of ionization and the amount of surfactant binding to polymer. The mean sizes of the aggregates were determined by the steady-state fluorescence quenching technique. The results are rationalized in terms of a mechanism of interaction which assumes that mean driving forces which, by exclusion of the others, must reside in the head group of surfactant and premicelles which always specifically coordinate with the polymer chain in those cases in which cac depression occurs. Evidence of the existence of premicelle was provided by following the effect of PEO concentration on the first-order rate constant-surfactant concentration profiles, in the presence of SDS, of acid-catalyzed hydrolysis of a moderated hydrophobic substrate, di- n-butyl benzaldehyde acetal.

The role of the counterion in poly(ethylene oxide)-dodecyl sulfate interactions

The effects of the counterions, Li +, Na + and tetramethylammonium (TMA +) of dodecyl sulfates on the interaction of poly(ethylene oxide) (PEO) have been investigated conductimetrically. For tetramethylammonium dodecyl sulfate (TMADS), significant effects on the classical conductivity vs surfactant profiles should be expected, compared to those for lithium dodecyl sulfate (LDS) and sodium dodecyl sulfate (SDS), since the main driving forces of the polymer binding should be attributed to the counterion. However, it has been found that the conductivity breakpoints, the critical aggregation concentration ( cac) and the polymer saturation point ( psp), and also other characteristics of the conductivity profiles investigated, such as linearity of the cac-psp region, ratios of slopes related to the degrees of dissociation of the polymer-surfactant complexes and micelles, and the amount of the complexed surfactant per monomol of PEO, do not exhibit differences sufficient to justify the importance of the counterion in the mechanism of polymer-surfactant interaction.