The Influence of Temperature on the Retention of Methanol by AOT Reverse Micelles: A Molecular Dynamics and First-Principles Study

Reverse micelles (RMs) are versatile self-assembled structures with wide-ranging applications. This study investigates the retention of methanol within AOT-based RMs in isooctane, focusing on the influence of temperature and methanol's interaction sites within the RM structure. Using molecular dynamics simulations at 298.15, 303.15, 308.15, and 313.15 K, we demonstrate that AOT RMs, ranging in size from 15 to 62 AOT molecules, effectively retain methanol, with retention increasing at higher temperatures. Our findings, supported by both molecular dynamics and ab initio calculations, reveal that methanol retention primarily occurs through hydrogen bonding between the methanol hydroxyl group and the oxygen atoms of the AOT polar headgroup. Furthermore, our analysis confirms the stability of RMs with varying water loads, including dry reverse micelles (dRMs), corroborating previous experimental and theoretical findings. Importantly, we show that while methanol predominantly resides near the polar heads at the core surface, the possibility of methanol penetrating the core, even in dRMs, cannot be excluded. This research provides valuable insights into methanol's behavior within AOT RMs, paving the way for further investigation into the formation and properties of these systems in the presence of methanol.