Developing and Validating Predictions of a Model for Reversible Scission and Deformation of Wormlike Micelles

Wormlike micelles formed from the assembly of amphiphilic molecules (e.g. block copolymers) break reversibly in solution. The Vasquez-Cook-McKinley (VCM) model for nonlinear rheology of such micellar solutions includes the reversible scission and deformation of these micelles but their results have yet to be validated with complimentary methods. We compare the predictions of the VCM model, which treats micelle networks as Hookean dumbbells that break at half-length to form two shorter dumbbells, to an analogous Brownian dynamics (BD) simulation. We find a discrepancy between the predictions of the VCM model and BD simulation and offer a revision to the VCM model to obtain predictions matching the BD simulation. The revision allows for tracking of the internal configuration of the micelle such that the relative orientations of shorter micelles are retained in the longer micelle resulting from the fusion of the shorter micelles. A general method for retaining this information is offered which can be applied to more general models of micelle breakage, rejoining, and flow orientation. Our new model also allows for the possibility that this relative orientation might affect the rate of fusion of micelles.