Kinetic Routes to Diblock Copolymer Micelles

Surfactant and polymer-based micelles are abundant in nature and widely utilized across diverse applications, from drug delivery to viscosity modification in oils and consumer products. Micelles equilibrate via two principal processes: chain expulsion/insertion and micelle fission/fusion. For surfactants and lipids, these processes occur on subsecond timescales, but in longer-chain diblock copolymers, higher free energy barriers significantly slow equilibration. This presents challenges for achieving equilibrium in micelle size and concentration, making it desirable in both experimental and industrial contexts to develop reliable methods for producing micelle solutions with targeted, narrow size distributions. In this study, we use coarse-grained molecular dynamics simulations to explore a pathway for forming large diblock copolymer micelles by dissolving a lamellar phase in a selective solvent. This lamella-to-micelle transition features an intermediate state resembling the cylindrical phase in diblock melts. We confirm that this method provides a more consistent micelle size distribution compared to direct self-assembly of dispersed copolymer in solution. We further examine how solvent quality and block length asymmetry influence the resulting size distribution. In addition, we explore the utility of pathways starting from different diblock phases.