Universal thermal response of the multiscale nanodomains formed in trans-anethol/ethanol/water surfactant-free microemulsion

TL;DR

This study investigates how temperature influences the phase behavior and nanodomain stability in a surfactant-free microemulsion system, revealing reversible tuning and distinct responses of different aggregate scales, advancing understanding for industrial applications.

Contribution

It provides the first detailed analysis of the thermal response of multiscale nanodomains in trans-anethol/ethanol/water microemulsions, demonstrating reversible control over their stability and phase behavior.

Findings

Temperature extends the monophasic zone in the system.

Multiscale nanodomains can be reversibly tuned by temperature changes.

Higher temperatures destabilize nanodomains, causing exponential decay in scattering intensity.

Abstract

Hypothesis: Surfactant-free microemulsion (SFME), an emerging phenomenology that occurs in the monophasic zone of a broad category of ternary mixtures 'hydrophobe/hydrotrope/water', has attracted extensive interests due to their unique physicochemical properties. The potential of this kind of ternary fluid for solubilization and drug delivery make them promising candidates in many industrial scenarios. Experiments: Here the thermodynamic behavior of these multiscale nanodomains formed in the ternary trans-anethol/ethanol/water system over a wide range of temperatures is explored. The macroscopic physical properties of the ternary solutions are characterized, with revealing the temperature dependence of refractive index and dynamic viscosity. Findings: With increasing temperature, the ternary system shows extended areas in the monophasic zone. We demonstrate that the phase behavior and the multiscale nanodomains formed in the monophasic zone can be precisely and reversibly tuned by altering the temperature. Increasing temperature can destroy the stability of the multiscale nanodomains in equilibrium, with an exponential decay in the scattering light intensity. Nevertheless, molecular-scale aggregates and mesoscopic droplets exhibit significantly different response behaviors to temperature stimuli. The temperature-sensitive nature of the ternary SFME system provides a crucial step forward exploring and industrializing its stability.