(618g) Kinetics and Mechanisms of Fusion in Block Copolymer Micelles

Block copolymer micelles have diverse applications, ranging from drug delivery to viscosity modification. The morphology and properties of micelles are influenced not only by their structure but also by their kinetics. However, studying micelle kinetics presents experimental challenges and involves various processes such as chain exchange, fusion, and fragmentation. In this talk, we will discuss the growth kinetics of block copolymer micelles in a highly selective solvent, where micelles grow primarily through fusion. Using a powerful combination of dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering, we describe the fusion kinetics of small, metastable micelles and highlight the main barrier to fusion: steric repulsion between micelles. We will also discuss the quantized nature of micelle fusion, where growth occurs in distinct steps, depending on micelle size. Initially, the aggregation number of micelles doubles, followed by a second, slower step in which the aggregation number continues to increase as fusion progresses.