The interaction of mixed surfactants with polyelectrolytes

Abstract

IntroductionIn most practical applications surfactant mixtures are used rather than a pure species [1]. The reason for this is frequently based on more favorable characteristics of mixtures and the lower cost of production than preparing the individual surfactant components involved. The synergistic properties of mixed surfactants have motivated much of the research in this ®eld [2].Most of the studies on mixed surfactant systems have been concerned with mixed micelle formation and mixed monolayers [3±6]. Little work has been carried out on interactions of surfactant mixtures with polymers, one of the common additives in applications [7,8]. In a previous paper, we developed an``ideal mixing/ideal cooperative binding'' model of the interaction of binary surfactants, tetradecylpyridinium chloride (TeP) and decylammonium chloride (DeA), with the oppositely charged poly(L-glutamate) [P(Glu)] [9]. A surfactantselective electrode was used to measure the equilibrium concentration of surfactant in solution and circular dichroism (CD) was used to investigate the conformational change of P(Glu) in the mixed surfactant solutions. Because the membrane electrode is much more responsive to TeP than to DeA (the electrode selectivity of DeA over TeP is about 0.003), at least the binding isotherms of TeP in the surfactant mixtures can be built up experimentally. Furthermore, with the help of theoretical considerations, individual binding isotherms were ®gured out separately. In order to see the applicability of the theoretical treatment, we have extended the investigation to a system composed of two homologous cationic surfactants, TeP and dodecylpyridinium chloride (DoP), and an anionic linear polymer, sodium poly(2-acrylamide-2-methylpropane sulfonate) (PAMPS). Since the linear polymer, PAMPS, does not assume any ordered structure in surfactant solution detectable by a CD method, spectroscopy is not suitable anymore. Moreover, the electrode membrane selectivity of DoP over TeP is about 0.12, i.e., the membrane is sensitive to both DoP and TeP. Neither the binding isotherms of TeP nor of DoP could be constructed from the experimental method. However, by using the same ideal mixing model, the binding isotherms of the mixed surfactants can be extracted from the limited experimental data, which helps us get an Abstract The interactions between a linear polymer, sodium poly(2-acrylamide-2-methylpropane sulfonate), and two cationic surfactants, dodecylpyridinium chloride and tetradecylpyridinium chloride and their mixtures with dierent ratios, were studied by a potentiometric titration method using a surfactant-selective electrode. The ideal mixing/ideal cooperative binding model we had proposed previously was applied to successfully predict the binding isotherms of the mixed surfactant systems and the critical aggregation concentrations of the binding. The binding of surfactant mixtures to polymers is similar to the ideal mixed micelle formation and a sort of synergetic eect was found during the binding process.

Binding of Photosurfactant (4-butyl-azobenzene-4′-oxyethyltrimethylammonium bromide) to Polyelectrolyte

“…The binding isotherm even bent backward a little when the cis compositions increase to 50 and 70% in the mixture. Similar results were also found in our previous works on the binding of TPC and DAC mixture to P(Glu) (13) and on the binding of TPC and DPC mixture to PAMPS (14).…”

“…Although there have been published excellent review works on polymer-surfactant systems (9 -12), very few works are referred to in this respect. To overcome this point, we have investigated binary surfactant-polyelectrolyte systems in previous papers and successfully analyzed by the ideal mixing-ideal cooperative binding model; binding of mixtures of tetradecylpyridinium chloride (TPC) and decylammonium chloride (DAC) to poly(L-glutamate) (p(Glu)) and of TPC and dodecylpyridinium chloride (DPC) to PAMPS (13,14). Here it will be shown that the same model is applied to the photosurfactant system together with some insight obtained from the analysis.…”

Surfactantion-selective electrodes: A promising approach to the study of the aggregation of ionic surfactants in solution

“…This kind of electrode has been extensively used by Wyn-Jones et al 48,[54][55][56][57]138,[140][141][142][143][144][145][146][147][148] and by the groups of Shirahama and Hayakawa. 49,[149][150][151][152][153][154] From Table 1, one can see that the polymers are mainly focused on PVP, PEO, PVA, HEUR, CD, MC, NaPA, PAMPS, Chitosan, and triblock-polymers such as Pluronic F68 (EO 76 PO 29 EO 76 ) and F127 (EO 97 PO 69 EO 97 ). [53][54][55][56]74 Anionic surfactants include sodium dodecyl sulfate (SDS), sodium tetradecyl sulfate (STS), etc.…”

“…With first section of the isotherms for all of the systems investigated, the binding is cooperative, but its strength was found to be dependent on the charge density of PAA in the preformed polyelectrolyte complex aggregates. Subsequently, Shirahama et al 150 have also studied the interactions between a linear polymer PAMPS, and two cationic surfactants, DPyCl and TPyCl and their mixtures with different ratios by a potentiometric titration method using SISEs. By using the ideal mixing/ideal cooperative binding model, they successfully predicted that the binding isotherms of the mixed surfactant systems and the cac of the binding, the binding isotherms and apparent binding isotherms were illustrated in Fig.…”

“…Fig.9(a) EMF vs. total surfactant concentration of DPyCl, TPyCl, and their mixtures in the absence and presence of PAMPS (c p ¼ 0.2 mmol dm À3 ), (b) Binding isotherms of TPyCl and DPyCl and apparent binding isotherms for the binary surfactants. Solid line: simulation of the ideal mixing/ideal cooperative binding model 150. …”