Adsorption Of Hydrophobically Modified Polyelectrolytes At The N-Octane/Water Interface”; Journal of Colloid and Interface Science, Vol. 261, issue 2, 559-564 (2003). (original) (raw)
Related papers
Adsorption of hydrophobically modified polyelectrolytes at the -octane/water interface
Journal of Colloid and Interface Science, 2003
The interfacial activity of polyelectrolytes carrying alkyl side chains of different length has been studied. Potassium salts of poly(maleic acid-co-1-olefins), PA-nK 2 with n = 12, 14, 16, 18, were synthesized, and the interfacial tension at the aqueous solution/n-octane interface was measured as a function of the length of the alkyl side chain. The results show that the interfacial tension lowering, the limiting excess concentration Γ m , and the efficiency of adsorption pC 20 depend on the number of methylene groups in the alkyl side chain. According to Rosen (Surfactants and Interfacial Phenomena, Wiley, New York, 1989) the last two parameters define two different contributions to the standard free energy of adsorption: one arises from the distribution of the polymer between the bulk of the solution and the interface G 0 dist , and another comes from the configuration adopted at the interface G 0 int . These free energies were plotted as a function of the number of carbon atoms in the alkyl side chain and a linear relation was found for both of them. From these plots contributions of 0.83 and −0.58 per methylene group were determined for G 0 dist and G 0 int , respectively. The positive value for the incremental free energy of distribution is attributed to the formation of a polymer micelle which is stabilized by longer alkyl side chains. On the other hand, the negative value for G 0 int indicates that at the interface the polymer adopts a configuration where the hydrocarbon tail is interacting with the octane molecules. (A.F. Olea).
Journal of Colloid and Interface Science, 2005
The interfacial properties of poly(maleic acid-alt-1-alkene) disodium salts at hydrocarbon/water interfaces are determined. In all the studied systems, the interfacial tension decreases markedly with the polyelectrolyte concentration as the side-chain length increases. The results of the standard free energy of adsorption, G 0 ads , are a linear function of the number of carbon atoms in the polyelectrolyte side chain. The contribution to G 0 ads per mol of methylene group varies from −0.64 to −0.52 kJ/mol for the n-octane/water to n-dodecane/water interfaces. G 0 ads data also reveal that the adsorption process is mainly determined by adsorption efficiency. Comparatively, the adsorption effectiveness seems to play a less important role. The theoretical interaction energies calculated for the insertion of one hydrocarbon molecule into the space formed by two neighboring polyelectrolyte side chains are in good agreement with the experimental results. The latter results are consistent with van der Waals-type interactions between the hydrocarbon molecules and the polyelectrolyte side chains.
Interaction between pentaethylene glycol n-octyl ether and low-molecular-weight poly(acrylic acid)
Journal of Colloid and Interface Science, 2004
The interaction between pentaethylene glycol n-octyl ether (C 8 E 5 ) and low-molecular-weight poly(acrylic acid) (PAA, M w = 2000) in aqueous solution has been investigated by various experimental techniques at constant polymer concentration (0.1% w/w) with varying surfactant molality. Spectrofluorimetry, using pyrene as molecular probe, shows (i) the formation of surfactant-polymer aggregates at a surfactant molality (T 1 ) lower than the critical micelle concentration (cmc) of C 8 E 5 in water and (ii) the formation of free micelles at a surfactant molality (T 2 ) slightly higher than the cmc. Fluorescence quenching measurements indicate that the presence of PAA induces a lowering of the C 8 E 5 aggregation number. Calorimetry confirms spectrofluorimetric evidence; in addition, it shows the presence of weak interactions below T 1 between monomeric surfactant molecules and the polymer chains. Tensiometry shows that, above T 1 , only a low fraction of surfactant molecules interact with the polymer and that free micelle formation occurs before polymer saturation. The peculiarities of the interaction between surfactants and low-molecular-weight polymers have been discussed.
Polymers, 2020
Alternating amphiphilic copolymers are macromolecular systems with a polarity duality in their structure, since they are generally formed by alternating segments corresponding to a potential electrolyte group and an alkyl (aliphatic or aromatic) group. These systems, depending on the ionization degree, as well as the time, may form different types of intra and interpolymeric aggregates in aqueous media. Therefore, this study, which in fact is the continuation of a previously reported work, is focused on establishing how the ionization degree of the sodium and potassium salts of the poly(maleic acid-alt-octadecene) affect zeta potential, pH, electrical conductivity, particle size, polydispersity index, and surface tension over time. The results showed that polymeric salts with a high ionization degree in aqueous media formed homogeneous systems with bimodal sizes and high zeta potential values, which tended to quickly become less negative, lowering the pH and slightly increasing the ...
Polyelectrolyte complex formation on a dimeric interface
Macromolecular Rapid Communications, 1994
It is well-known that polyelectrolytes interact with various low-and highmolecular-weight substances and form interpolyelectrolyte complexes (PEC) which usually precipitate from aqueous solution
Adsorption kinetics of hydrophobic polysoaps at the methylene chloride–water interface
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004
The kinetics of the adsorption of hydrophobic insoluble in water polymers (ammonio polymethylmethacrylates, known as Eudragits RL and RS) at the methylene chloride (MC)-water interface has been studied in function of their bulk concentration in the organic phase. These polymers, conventionally denoted as hydrophobic polysoaps, strongly adsorb at the oil-water interface by immersing their ionisable (trimethylammonium (TMA)) groups into the water phase. Unlike the hydrophilic polysoaps (the water-soluble hydrophobically modified polyelectrolytes) whose adsorption at the oil-water interface is controlled by the hydrophobic effect (the gain in entropy due to the destruction of the ordered layers of the water molecules around the adsorbed alkyl chains), the driving force for the adsorption of hydrophobic polysoaps is the gain in enthalpy due to the hydration of adsorbed hydrophilic groups of the polymer. It has been shown that the dynamic interfacial tension curves γ(t) of hydrophobic polysoaps are characterized by several stages of adsorption with different characteristic relaxation times. During the lag-stage and the post lag-stage the adsorption is the diffusion-controlled process of macromolecules from the bulk of the organic solution to the interface. At the final stage, the adsorption is characterized by much lower rate due to the steric hindrance exerted by the yet formed adsorption layer with regard to newly adsorbing macromolecules.
Journal of Colloid and Interface Science, 2000
The interactions between PEO and sodium alkylcarboxylates (octyl, decyl, and dodecyl) have been investigated by conductivity measurements and gel permeation chromatography (GPC). Also included in the study was sodium dodecyl sulfate. From the conductivity measurements the critical aggregation concentration, ionization degree, and binding ratios were determined; the binding ratio was also determined from GPC. PEO-surfactant interactions were observed for all the studied surfactants, except sodium octanoate. For the polymer-surfactant complexes the ionization degree was in all cases observed to be about 0.2 higher than the ionization degree for the corresponding aqueous micelles. Further, the binding ratio decreased somewhat with decreasing chain length of the alkylcarboxylate. The Gibbs free energy showed that the polymersurfactant interaction decreases with decreasing chain length of the alkylcarboxylates and is weaker for alkylcarboxylate compared to alkylsulfate of similar chain length. C 2000 Academic Press
The interactions between polyelectrolytes and AOT in an oil/water system
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1997
The interactions between sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and polyelectrolytes were studied by measuring the mass transfer of polycations from an aqueous to a reverse micellar phase. The quarternized poly(vinylpyridine) derivatives reacted with AOT and formed an insoluble complex (in isooctane or water) whenever surfactant/cationic monomer concentration ratio was less than 1.4. Surplus AOT in the system led to quantitative transfer of the complex from the aqueous to the micellar phase, which indicates a strong role of electrostatic interactions and probably hydrophobic ones. The phase behaviour and ion balance suggest a mode of "solubilization" of the polyelectrolytes in the micellar solution that differs from the previously observed incorporation of solute molecules into the reverse micelle. In the case investigated, the reverse micelles and surfactant-polyelectrolyte complex co-exist. The results of sedimentation (ultracentrifuge) measurements indicated strong interactions between the polyelectrolyte-AOT complex and the reverse micelles. The mass balance of AOT and water also suggests a certain kind of aggregation between the reverse micelles and the polyelectrolyte-surfactant complex. When barium was used instead of sodium as the counterion to AOT, the stoichiometry of the interphase-micellar phase transition changed from an AOT/monomer ratio of 1.4:1 to 1.1:1. The yield of the mass transfer of the protonated polyvinylpyridine was much lower than that of the quaternized product in the same system. A saturation-like isotherm of extraction was obtained if the AOT surplus was at least 20-fold. At AOT/monomer concentration ratios below 20, a third phase was formed. The addition of co-surfactants (n-alkanols) strongly increased the efficiency of mass transfer, but the critical AOT/monomer concentration ratio at the transition point (the appearance of a third phase or a clear oil/water system) remained the same.