Conductometric, Surface Tension, and Kinetic Studies in Mixed SDS−Tween 20 and SDS−SB3-12 Micellar Solutions

Abstract

Micellization in sodium dodecyl sulfate (SDS)-N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and SDS-polyoxyethylenesorbitan monolaurate binary surfactant solutions was studied by means of conductivity and surface tension measurements. These studies showed that two types of micellar aggregates are present in the mixed micellar solutions. Two reactions were investigated in these micellar media, the oxidation of 1-methoxy-4-(methylthio)benzene by IO(4)(-) and the spontaneous hydrolysis of phenyl chloroformate. Information on the distribution of reagents in the micellar reaction media was obtained through conductivity and spectroscopic measurements. Discussion of the kinetic data showed that the redox reaction takes place mainly in the aqueous phase of the mixed solutions, whereas hydrolysis occurs in the aqueous as well as in the micellar pseudophase. Variations in the observed rate constants of the two processes studied are gradual within the whole surfactant concentration range investigated, revealing little information about the mixed micellar medium.

Phase Behavior and Rheological Properties of a Salt-Free Catanionic Surfactant TTAOH/LA/H2O System

“…The measurements gave well-resolved data with critical micellar concentration (cmc) equal to or slightly higher than 0.1 mmol·L −1 . This is consistent with the values obtained for salt-containing catanionic systems but in contrast with those obtained for single-chain cationic and anionic surfactants including TTABr (cmc: 3.7 mmol·L −1 ), TTAOH (cmc: 1.8 mmol·L −1 from surface tension measurement and 3.6 mmol·L −1 from conductivity measurement), , and SDS (cmc: 8.1 mmol·L −1 ) . The high effectiveness of lowering surface tension for catanionic systems can be explained by an effective reduction of the area of their hydrophilic headgroups after ion-pairing between cationic and anionic surfactants, resulting in more densely packing at the air/water interface compared to single cationic or anionic surfactants.…”

Phase Behavior and Rheological Properties of a Salt-Free Catanionic Surfactant TTAOH/LA/H2O System

“…The measurements gave well-resolved data with critical micellar concentration (cmc) equal to or slightly higher than 0.1 mmol·L −1 . This is consistent with the values obtained for salt-containing catanionic systems but in contrast with those obtained for single-chain cationic and anionic surfactants including TTABr (cmc: 3.7 mmol·L −1 ), TTAOH (cmc: 1.8 mmol·L −1 from surface tension measurement and 3.6 mmol·L −1 from conductivity measurement), , and SDS (cmc: 8.1 mmol·L −1 ) . The high effectiveness of lowering surface tension for catanionic systems can be explained by an effective reduction of the area of their hydrophilic headgroups after ion-pairing between cationic and anionic surfactants, resulting in more densely packing at the air/water interface compared to single cationic or anionic surfactants.…”

Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) mixed micelles in aqueous solution

“…The presence of these two breaks suggests the existence of two types of mixed micelles, where each break corresponds to one cmc. Existence of two break points in SDS-Tween 20 mixtures was also found by Munoz et al [28]. For mixed SDS-Triton X-100 binary system, only one cmc (one break) was noticed, for all molar ratios.…”

“…The first cmc for mixtures of SDS-Tween 85 (α = 0.4 or 0.5) could not be studied since conductivities corresponding to these dilute solutions are too low. The first break at low surfactant concentration corresponds to mixed micelles richer in nonionic surfactant, as found by Munoz et al [28]. The second break, at higher surfactant concentrations represents another type of mixed micelles with unknown mole fractions of the surfactants because pure or mixed micelles are formed previously [28].…”

Hydrophobic tail length plays a pivotal role in amyloid beta (25-35) fibril-surfactant interactions

“…54,55 Higher disaggregating property of CTAB is proposed to be a result of attachment and then further interaction between larger hydrophobic tails of the surfactant and the fibrils. Such dependence of hydrophobic interaction is also observed in previously reported work by Xiong et al where hydrophobic matching dominated the secondary structural aspects of Ab [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and its interaction with lipid bilayer. 56 The predominance of hydrophobic interactions over electrostatic interactions were found to occur in the work reported by D'Errico et al where the authors show that the presence of charges in the phospholipid bilayer hardly affected the interaction of the monomeric Ab [25][26][27][28][29][30][31][32][33][34][35] peptide with lipid membranes.…”

Phase Behavior and Rheological Properties of a Salt-Free Catanionic Surfactant TTAOH/LA/H2O System

“…The measurements gave well-resolved data with critical micellar concentration (cmc) equal to or slightly higher than 0.1 mmol·L −1 . This is consistent with the values obtained for salt-containing catanionic systems but in contrast with those obtained for single-chain cationic and anionic surfactants including TTABr (cmc: 3.7 mmol·L −1 ), TTAOH (cmc: 1.8 mmol·L −1 from surface tension measurement and 3.6 mmol·L −1 from conductivity measurement), , and SDS (cmc: 8.1 mmol·L −1 ) . The high effectiveness of lowering surface tension for catanionic systems can be explained by an effective reduction of the area of their hydrophilic headgroups after ion-pairing between cationic and anionic surfactants, resulting in more densely packing at the air/water interface compared to single cationic or anionic surfactants.…”

Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) mixed micelles in aqueous solution

“…The presence of these two breaks suggests the existence of two types of mixed micelles, where each break corresponds to one cmc. Existence of two break points in SDS-Tween 20 mixtures was also found by Munoz et al [28]. For mixed SDS-Triton X-100 binary system, only one cmc (one break) was noticed, for all molar ratios.…”

“…The first cmc for mixtures of SDS-Tween 85 (α = 0.4 or 0.5) could not be studied since conductivities corresponding to these dilute solutions are too low. The first break at low surfactant concentration corresponds to mixed micelles richer in nonionic surfactant, as found by Munoz et al [28]. The second break, at higher surfactant concentrations represents another type of mixed micelles with unknown mole fractions of the surfactants because pure or mixed micelles are formed previously [28].…”

Hydrophobic tail length plays a pivotal role in amyloid beta (25-35) fibril-surfactant interactions

“…54,55 Higher disaggregating property of CTAB is proposed to be a result of attachment and then further interaction between larger hydrophobic tails of the surfactant and the fibrils. Such dependence of hydrophobic interaction is also observed in previously reported work by Xiong et al where hydrophobic matching dominated the secondary structural aspects of Ab [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and its interaction with lipid bilayer. 56 The predominance of hydrophobic interactions over electrostatic interactions were found to occur in the work reported by D'Errico et al where the authors show that the presence of charges in the phospholipid bilayer hardly affected the interaction of the monomeric Ab [25][26][27][28][29][30][31][32][33][34][35] peptide with lipid membranes.…”

Phase Behavior and Rheological Properties of a Salt-Free Catanionic Surfactant TTAOH/LA/H2O System

“…The measurements gave well-resolved data with critical micellar concentration (cmc) equal to or slightly higher than 0.1 mmol·L −1 . This is consistent with the values obtained for salt-containing catanionic systems but in contrast with those obtained for single-chain cationic and anionic surfactants including TTABr (cmc: 3.7 mmol·L −1 ), TTAOH (cmc: 1.8 mmol·L −1 from surface tension measurement and 3.6 mmol·L −1 from conductivity measurement), , and SDS (cmc: 8.1 mmol·L −1 ) . The high effectiveness of lowering surface tension for catanionic systems can be explained by an effective reduction of the area of their hydrophilic headgroups after ion-pairing between cationic and anionic surfactants, resulting in more densely packing at the air/water interface compared to single cationic or anionic surfactants.…”

Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) mixed micelles in aqueous solution

“…The presence of these two breaks suggests the existence of two types of mixed micelles, where each break corresponds to one cmc. Existence of two break points in SDS-Tween 20 mixtures was also found by Munoz et al [28]. For mixed SDS-Triton X-100 binary system, only one cmc (one break) was noticed, for all molar ratios.…”

“…The first cmc for mixtures of SDS-Tween 85 (α = 0.4 or 0.5) could not be studied since conductivities corresponding to these dilute solutions are too low. The first break at low surfactant concentration corresponds to mixed micelles richer in nonionic surfactant, as found by Munoz et al [28]. The second break, at higher surfactant concentrations represents another type of mixed micelles with unknown mole fractions of the surfactants because pure or mixed micelles are formed previously [28].…”

Hydrophobic tail length plays a pivotal role in amyloid beta (25-35) fibril-surfactant interactions

“…54,55 Higher disaggregating property of CTAB is proposed to be a result of attachment and then further interaction between larger hydrophobic tails of the surfactant and the fibrils. Such dependence of hydrophobic interaction is also observed in previously reported work by Xiong et al where hydrophobic matching dominated the secondary structural aspects of Ab [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and its interaction with lipid bilayer. 56 The predominance of hydrophobic interactions over electrostatic interactions were found to occur in the work reported by D'Errico et al where the authors show that the presence of charges in the phospholipid bilayer hardly affected the interaction of the monomeric Ab [25][26][27][28][29][30][31][32][33][34][35] peptide with lipid membranes.…”