Self-Assembly, Surface Activity and Structure of n-Octyl-β-D-thioglucopyranoside in Ethylene Glycol-Water Mixtures

Abstract

The effect of the addition of ethylene glycol (EG) on the interfacial adsorption and micellar properties of the alkylglucoside surfactant n-octyl-β-d-thioglucopyranoside (OTG) has been investigated. Critical micelle concentrations (cmc) upon EG addition were obtained by both surface tension measurements and the pyrene 1:3 ratio method. A systematic increase in the cmc induced by the presence of the co-solvent was observed. This behavior was attributed to a reduction in the cohesive energy of the mixed solvent with respect to pure water, which favors an increase in the solubility of the surfactant with EG content. Static light scattering measurements revealed a decrease in the mean aggregation number of the OTG micelles with EG addition. Moreover, dynamic light scattering data showed that the effect of the surfactant concentration on micellar size is also controlled by the content of the co-solvent in the system. Finally, the effect of EG addition on the microstructure of OTG micelles was investigated using the hydrophobic probe Coumarin 153 (C153). Time-resolved fluorescence anisotropy decay curves of the probe solubilized in micelles were analyzed using the two-step model. The results indicate a slight reduction of the average reorientation time of the probe molecule with increasing EG in the mixed solvent system, thereby suggesting a lesser compactness induced by the presence of the co-solvent.

Influences of Crystal Anisotropy in Pharmaceutical Process Development

“…The presence of additives in solution, giving rise to surface activity, changes its wettability. In the presence of surface active agents such as polymers ( 202 , 203 ), and surfactants ( 204 , 205 ), the wettability mechanism is driven by their tendency to migrate towards the three phase contact line ( 69 , 70 ). This influence has been highlighted in a very detailed way in the concept of carbamazepine dihydrate ( 129 ).…”

Micellization and related behavior of sodium dodecylsulfate in mixed binary solvent media of tetrahydrofuran (Tf) and formamide (Fa) with water: a detailed physicochemical investigation

“…m with solvent parameters Effects of mixed solvents on the self-assembly formation of surfactants are reported in the literature. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] In most cases, attempts were made to correlate the CMC with solvent parameters viz., viscosity(h o ), permittivity (3), dipole moment (m), E T (30), Gordon parameter (G), Hansen-Hildebrand parameters (dispersion, d D ; polar, d P ; hydrogen bonding, d h ), polarity index (p*), Gutman donor number (DN), etc. Hydrogen bonding, solvent structure, solvent polarity and viscosity (or uidity) can affect the molecular association of the amphiphile species, a single parameter may not be adequate for the explanation.…”

“…Towards this end, potential studies with ionic, nonionic and zwitterionic surfactants in mixed aquo-organic solvent media have been conducted. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Studies on micellization of ionic and nonionic surfactants, as well as polymers in pure formamide (Fa) are available in the literature. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] It has been shown that the driving force for the initial solvophobicity towards the amphiphiles has similarities with the hydrophobic effect that arises from the large cohesive energy of the solvent like water.…”