Alkane selection as a critical factor in structuring reverse wormlike micelles.

Abstract

Hypothesis: The oil phase controls the persistence length and aqueous channel diameter of reverse wormlike micelles (RWLMs), specifically by tuning the cohesive energy density of alkanes.

Experiments: We explore the influence of alkanes with varying chain lengths on the rheological properties, structural parameters, and morphology of RWLMs. To establish a link between the solvent characteristics and the structure of RWLMs, we employ a diverse set of complementary techniques, including rheological analysis, small-angle X-ray scattering (SAXS), Fourier-transform infrared (FT-IR) spectroscopy, and cryogenic transmission electron microscopy (cryo-TEM).

Findings: Our results show that the cross-sectional area and persistence length of reverse wormlike micelles (RWLMs) are influenced by the chain length of the alkanes in which the long aggregates are formed. We propose a model based on the Hildebrand solubility parameter to explain this behavior, where alkanes with higher cohesive energy density led to RWLMs with narrower aqueous channels. Selecting specific alkanes makes it possible to fine-tune the diameter of these channels, presenting promising opportunities for designing RWLMs tailored to confined media applications.