Small-Angle Neutron-Scattering and Viscosity Studies of CTAB/NaSal Viscoelastic Micellar Solutions

and, V. K. Aswal; Goyal, P. S.; Thiyagarajan, P.

doi:10.1021/jp980181f

Cited by 182 publications

(176 citation statements)

References 32 publications

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“…In contrast, with R 4 N salts the viscosity increased (part I), decreased (part II), and increased again (part III). This behavior is new but akin to that observed with Na salts of organic acids (26,27), which have an altogether different origin (28). With KBr, the continuous viscosity increase may be due to the synergistic effect of Br − and C 7 NH 2 (as discussed in the previous paragraph).…”

Section: Resultsmentioning

confidence: 53%

Role of quaternary bromides in changing the solubilization site of n‐heptylamine in cationic micellar solutions

Kumar

Sharma

Kabir-ud-Din

2003

J Surfact & Detergents

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Newtonian flow conditions were adopted to take viscosity measurements at 30°C of solutions of cationic surfactants (cetyltrimethylammonium bromide, C 16 TAB, and tetradecyltrimethylammonium bromide, C 14 TAB) with the addition of n-heptylamine (C 7 NH 2 ) and quaternary salts (tetra-npropylammonium bromide, Pr 4 NBr; tetra-n-butylammonium bromide, Bu 4 NBr; tetraamylammonium bromide, Am 4 NBr; tetra-n-octylammonium bromide, Oc 4 NBr; tetra-n-butylphosphonium bromide, Bu 4 PBr; tetraphenylphosphonium bromide, Φ 4 PBr; n-propyltriphenylphosphonium bromide, PrΦ 3 PBr) by having either a fixed C 7 NH 2 or salt concentration and varying the other. Systems containing a comparatively higher Bu 4 NBr content showed a dramatic decrease in viscosity at higher C 7 NH 2 concentration. Further, the viscosity-salt concentration profiles of 0.1 M C 16 TAB solutions containing fixed C 7 NH 2 concentrations showed a peaked behavior. The peak positions and salt contents at the peaks were dependent on the length of the alkyl part of the particular salt and the connecting atom (N or P) but independent of the nature of the surfactant and C 7 NH 2 concentration. The behavior is discussed in the light of a change in the solubilization site of C 7 NH 2 caused by the presence of quaternary salts. Cavities in the quaternary salts present in the bulk solvent are proposed to be the new sites of solubilization.

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Section: Resultsmentioning

confidence: 53%

Role of quaternary bromides in changing the solubilization site of n‐heptylamine in cationic micellar solutions

Kumar

Sharma

Kabir-ud-Din

2003

J Surfact & Detergents

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“…A further increase in the concentration above the CMC values resulted in greater selectivity of the Diels-Alder adduct towards the endo product. This might be due to a change in the shape of the micelles when the concentration of the surfactant is increased well above its CMC [33] which favoured the kinetic endo product over the thermodynamic one. However, at this particular concentration, a drop in the yield of the product was observed which might be explained by the change in the micellar structure which rendered the reaction unfavorable.…”

Section: Resultsmentioning

confidence: 99%

The use of optically active O-alkyl ester hydrochlorides of L-phenylalanine and L-tyrosine as chiral micellar media for the catalysis of diels-alder reactions

Caumul¹,

Koonja²,

Namooya³

et al. 2018

Bull. Chem. Soc. Eth.

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ABSTRACT. The effect of a range of O-alkyl ester hydrochloride surfactants derived from L-phenylalanine and L-tyrosine as catalysts on the Diels-Alder reaction between cyclopentadiene and methyl acrylate was studied. Both chain lengths (C8-C14) and head groups of the surfactants were found to influence the yield and selectivity of the Diels-Alder product. The C10 derivatives of both phenylalanine and tyrosine surfactants gave the highest yields and selectivity. Phenylalanine ester hydrochlorides showed better catalytic activity than the tyrosine derivatives. Adduct optimum yield was obtained at a concentration relating to their critical micelle concentration (CMC) values. The Diels-Alder reaction was also found to be favored in acidic condition (pH 3) as well as in the presence of lithium chloride (LiCl) as salting out agent.

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“…Required amounts of antioxidants were weighed into 30 ml vials and added to 20 3 methyl gallate (MG) R = C 2 H 5 ethyl gallate (EG) R = C 3 H 7 propyl gallate (PG) R = C 4 H 9 butyl gallate (BG) R = C 8 H 17 octyl gallate (OG) or to 5 ml of D 2 O acetic buffer solution with equivalent surfactant concentrations. Samples needed to be heated to 60…”

Section: Viscositymentioning

confidence: 99%

“…Various studies using a variety of techniques such as rheological approaches, [7][8][9][10][11][12] birefringence, 8 NMR, 4,5,8,13,14 heat capacity, 15 acidity, 13 neutron reflectivity, 6 surface tension, 16 and SANS measurements 4,17,18 have been performed on the influence of organic counterions on cationic surfactants. It has been demonstrated that aromatic counterions are more effective at lower concentrations than salts or electrolytes in inducing the micellar growth, 6,13,19 which can be attributed to interactions with the aromatic π-electron system.…”

Section: Introductionmentioning

confidence: 99%

Impact of Phenolic Antioxidants on Structural Properties of Micellar Solutions

et al. 2006

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Antioxidants solubilized in micellar solutions can change micellar properties like the size and shape of micelles, critical micellar concentration (cmc) and viscosity. Interactions arising between antioxidants and the surfactant determine the locations of antioxidants and vice versa. The location and interaction are dependent on the type of both the antioxidant and surfactant. Influences of various antioxidants on the physical and structural properties were tested in micellar systems of cationic CTAB, non-ionic Brij 58 and anionic SDS. The antioxidants used to investigate the effects of gradually increasing lipophilicity were gallic acid (GA) and the gallate esters from methyl to octyl gallate (MG-OG). Hydroxy cinnamic acids (HCAs) like p-coumaric acid (pC), caffeic acid (CA), ferulic acid (FA) and sinapic acid (SA) were employed to observe effects of functional groups like hydroxyl and methoxy groups. Micellar size and shape determined by small angle neutron scattering (SANS), viscosity and cmc were chosen to characterize the antioxidant influence. In Brij 58 systems propyl gallate (PG) did not affect the cmc or aggregation number but decreased micellar size slightly due to an intercalation of PG into the region of the polyoxyethylene chain and the first adjacent alkyl chain methylene groups. In SDS systems the micellar size and cmc decreased in the presence of PG. This was attributed to PG residing in the Stern layer. However, in CTAB systems micelles swelled at low PG concentration and in the presence of GA, while higher PG concentrations and more lipophilic antioxidants led to a sphere-to-rod transition with a simultaneous increase in viscosity and decrease in cmc. This revealed the intercalation of antioxidants in the palisade layer of CTAB micelles entering into strong interactions of electrostatic and hydrophobic origin. It could be demonstrated that the interactions became stronger the more lipophil an antioxidant is and the more hydroxyl groups are attached to the aromatic ring. Differences in the location and interaction of antioxidant and micelles are proposed as being responsible for the effectiveness of antioxidants.

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Small-Angle Neutron-Scattering and Viscosity Studies of CTAB/NaSal Viscoelastic Micellar Solutions

Cited by 182 publications

References 32 publications

Role of quaternary bromides in changing the solubilization site of n‐heptylamine in cationic micellar solutions

Role of quaternary bromides in changing the solubilization site of n‐heptylamine in cationic micellar solutions

The use of optically active O-alkyl ester hydrochlorides of L-phenylalanine and L-tyrosine as chiral micellar media for the catalysis of diels-alder reactions

Impact of Phenolic Antioxidants on Structural Properties of Micellar Solutions

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