Quantitative analysis and subsequent effects of partitioning of a mono- and dihydric C4 alcohols into the micelles of cationic surfactants

Surfactant–alcohol systems are not uncommon in colloidal chemistry, what is rare is a specific emphasis on the environmental sensitive behaviour of 1-butanol (C4OH) in different surfactant solutions. Intermediate solubility of C4OH (in between totally soluble short chain alcohol and partially miscible long chain alcohol) has prompted us to study its partitioning between bulk and micellar phase for monomeric and dimeric surfactants and consequences on micellar parameters. Micellar aggregation number (Nagg) and micelle size has been evaluated by using SANS. Partitioning of C4OH between bulk and micellar phase was evaluated from 2D NMR NOESY and DOSY experiments. The effect of the structure of C4 alcohol was evaluated by taking all the above studies for 1,4-butanediol (1,4-BTD), a non-partitioning alcohol by virtue of its terminal hydroxyl groups. Finally, results from SANS and NMR are supported by the routine study of micellar behaviour from conductivity and viscosity. It is revealed that C4 alcohol plays substantial role in micellization and the two alcohols contribute differently in controlling the overall micellization and micellar parameters.

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► Mono- and dihydric alcohols get incorporated into the micelles of electrically similar but structurally different surfactants.
► The partitioning of 1-butanol and 1,4-butanediol into the micelles of single dimeric cationic surfactants is evaluated both qualitatively and quantitatively.
► Two-dimensional nuclear overhauser enhancement spectroscopy (NOESY) is used to locate 1-butanol and 1,4-butanediol into the micellare solution.
► Small angle neutron scattering (SANS) technique is used to know effect of addition of mono- and dihydric alcohols on size/shape and aggregation number of micelles.