Aggregation behavior of α,ω-type nonionic surfactant in aqueous solution

Ishikawa, Motoharu; Matsumura, Ken-Ichiro; Esumi, Kunio; Meguro, Kenjiro; Binana-Limbelé, W.; Zana, R.

doi:10.1016/0021-9797(92)90238-h

Cited by 12 publications

(5 citation statements)

References 59 publications

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“…The figure shows that both at low and the high temperature the diffusion coefficient increases with increase in the copolymer concentrations, which suggests that the intermicellar interaction remains predominantly repulsive even near the cloud point. 70,71 The diffusion coefficient obtained near the cloud point are much lower than those obtained at 35 °C due to the growth of the micelles with increase in temperature. Because the reported stickiness parameters of the micelles are quite low at high copolymer concentrations (Figure 5), the large difference in the diffusion coefficient in that concentration range cannot be explained based on the adhesive hard-sphere model.…”

Section: Resultsmentioning

confidence: 88%

Pluronic L64 Micelles near Cloud Point: Investigating the Role of Micellar Growth and Interaction in Critical Concentration Fluctuation and Percolation

Ganguly¹,

Choudhury²,

Aswal³

et al. 2008

J. Phys. Chem. B

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The structure and the properties of the (Ethylene Oxide)(13)(Propylene Oxide)(30)(Ethylene Oxide)(13) (Pluronic L64, MW approximately 2900) micelles have been studied in the aqueous medium by small angle neutron scattering (SANS), dynamic light scattering (DLS) and viscometry measurements. The aqueous solutions of this triblock copolymer are unique among the pluronic solutions in showing critical concentration fluctuations and a concomitant enhancement in viscosity on approaching their cloud point. So far these results have been attributed solely to the presence of attractive interaction between the spherical L64 micelles. Recent theoretical studies, on the other hand, suggest that L64 micelles prefer a prolate ellipsoidal structure to sphere (Bedrov et al. Langmuir 2007, 23, 12032) and have a predominantly repulsive intermicellar interaction. A comparative analysis of our SANS data based on the spherical and prolate ellipsoidal structure shows that the L64 micelles can be best described by a prolate ellipsoidal structure, the aspect ratios of which increase progressively with increase in temperature. This, together with our viscosity and DLS studies, suggests that the enhanced viscosity of the copolymer solution near the cloud point arises largely due to the anisotropic growth of the micelles to the worm-like structures. The role of the intermicellar attractive interaction has thus been limited to the observed critical concentration fluctuation, and its effect decreases progressively with increase in copolymer concentration. It has also been shown that the water structure making salts like NaCl reduces the micellar growth temperature and helps in forming worm-like micelles at the room temperature. These studies thus identify the effect of micellar growth and interaction in determining the properties of the copolymer solution near the cloud point, which are the first of its kind in the case of the pluronics.

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Section: Resultsmentioning

confidence: 88%

Pluronic L64 Micelles near Cloud Point: Investigating the Role of Micellar Growth and Interaction in Critical Concentration Fluctuation and Percolation

Ganguly¹,

Choudhury²,

Aswal³

et al. 2008

J. Phys. Chem. B

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“…Surfactants are characterized by their hydrophilic head group, i.e., cationic (positively charged), anionic (negatively charged), zwitterionic (doubly charged, positive and negative), or nonionic (non-charged). Gemini, or dimeric surfactants, have two matching head groups connected by a linking chain, the most common being an alkylene chain; [1][2][3][4][5][6][7][8] the hydrophobic tails of the head groups may be the same (symmetric gemini surfactant) or different (asymmetric gemini surfactant). The symmetric members of the cationic gemini surfactants listed in the above references are the most commonly studied in the literature, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] whereas anionic, [25][26][27][28][29][30][31] zwitterionic, [32][33][34] and nonionic gemini [35][36][37] surfactants are comparatively less studied.…”

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confidence: 99%

Asymmetric cationic gemini surfactants: an improved synthetic procedure and the micellar and surface properties of a homologous series in the presence of simple salts

et al. 2018

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The micellar and morphological properties of symmetric, cationic gemini surfactants have been well studied in the literature as a function of nature and type of the spacer group and the length and type of hydrophobic chain. In this paper, we have examined the effects of tail asymmetry on the properties of a series of cationic surfactants, the N-alkyl-1-N′-alkyl-2-N,N,N′,N′-tetramethyldiammonium dibromide. A novel synthetic method is used to prepare a series of these surfactants and the consequences of asymmetry on micellar properties are presented. This new method has been shown to be more efficient, with higher yields of the asymmetric surfactants than the yields of the accepted literature method. The critical micelle concentration values and the micelle sizes of the asymmetric gemini surfactants, 12-4-12, 12-4-10, 12-4-8, and 12-4-6 gemini surfactants, were obtained from conductivity and dynamic light scattering. With increasing chain asymmetry, the size of the micelle increased due to the formation of loose micelles. The addition of NaCl and Na2SO4 to the surfactant solutions increased the aggregate size, and this effect was more pronounced with increasing salt concentrations. These results are interpreted in terms of the effect these ions have on the “compactness” of the micelle structure.

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“…Long chain ax alkanediols would face some difficulty in penetrating into the micellar interior and contribute to hydrophobic interaction. 1,6-Hexanediol and 1,8-octanediol tend to remain in the palisade layer, due to the long chain adopting a wicket-like folded structure much like the conformation adopted by bolaform surfactants [33,34]. These conformations require more space between two molecules of the micelle, which results in an increase in the hydrodynamic size of the MCP micelles.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Light Scattering Studies on the Effect of 1‐Alkanols, Alkanediols and Alkoxyethanols on the Micelles of a Moderately Hydrophobic/Hydrophilic PEO‐PPO‐PEO Triblock Copolymer

Parekh

Bahadur

2011

J Surfact & Detergents

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The results on changes in the apparent hydrodynamic diameter (D h ) of micelles in a solution containing 5% of a moderately hydrophobic/hydrophilic triblock PEO-PPO-PEO copolymer in the presence of several hydroxyl compounds at 23°C from dynamic light scattering (DLS) are reported. Distribution plots show micelles with hydrodynamic diameter *17 nm and low polydispersity (\0.1) except at low concentrations where a unimer peak (* 4 nm) was also noticed. These additives increase/ decrease the micelle size and show micellar transition depending upon their hydrophilicity/hydrophobicity. The results are discussed in terms of the effect of the additives on altering water structure and their partitioning in micelle. Short chain alcohols (C 1 -C 3 ) increase solvation of PEO and thus increase micelle hydrodynamic size while higher alcohols, initially reduce D h due shrinkage of PEO followed by micellar growth at higher concentrations. Among ax-alkanediols, C 2 and C 4 diols increase micelle size by immobilizing water sphere around the micelles whereas higher diols form wicket like structures and reside in palisade layer. Isomeric hexanediols (1,2; 1,5; 2,5 and 1,6) alter micelle size in different ways depending on their hydrophobicity. In C 6 EO m (m = 0, 1, 2), as the number of EO group increases, it becomes more hydrophilic and increases D h at higher concentration. Addition of a hydrophobic triblock copolymer leads to unfavorable mixing with a moderately hydrophobic/hydrophilic triblock copolymer which results in increase in size, while the addition of a hydrophilic counterpart increases the average hydrodynamic size and follows appearance of unimer peak.

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Aggregation behavior of α,ω-type nonionic surfactant in aqueous solution

Cited by 12 publications

References 59 publications

Pluronic L64 Micelles near Cloud Point: Investigating the Role of Micellar Growth and Interaction in Critical Concentration Fluctuation and Percolation

Pluronic L64 Micelles near Cloud Point: Investigating the Role of Micellar Growth and Interaction in Critical Concentration Fluctuation and Percolation

Asymmetric cationic gemini surfactants: an improved synthetic procedure and the micellar and surface properties of a homologous series in the presence of simple salts

Dynamic Light Scattering Studies on the Effect of 1‐Alkanols, Alkanediols and Alkoxyethanols on the Micelles of a Moderately Hydrophobic/Hydrophilic PEO‐PPO‐PEO Triblock Copolymer

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