Dynamics and Scission of Rodlike Cationic Surfactant Micelles in Shear Flow

TL;DR

This study uses molecular dynamics simulations to explore how rodlike cationic surfactant micelles behave and break under shear flow, revealing the relationship between shear rate, micelle stretching, electrostatic interactions, and scission.

Contribution

First simulation-based analysis of flow-induced micelle dynamics and scission, linking electrostatic energy to micelle length and shear conditions.

Findings

Tumbling frequency depends on shear rate as predicted by mesoscopic theories.

Micelle stretching reduces electrostatic screening, increasing energy linearly with length.

Scission occurs when electrostatic energy exceeds a threshold, regardless of shear rate.

Abstract

Flow-induced configuration dynamics and scission of rodlike micelles are studied for the first time using molecular dynamics simulations in presence of explicit solvent and salt. Predicted dependence of tumbling frequency and orientation distribution on shear rate S agrees with mesoscopic theories. However, micelle stretching increases the distance between the cationic head groups and adsorbed counter ions, which reduces electrostatic screening and increases the overall energy Phi linearly with micelle length. Micelle scission occurs when Phi exceeds a threshold value, independent of S.