Small Angle Neutron Scattering Studies on Block Copolymer Micelles with Varying Core-Solvent Interactions

Diblock copolymers are amphiphilic molecules, which spontaneously form micelles in a selective solvent. Through careful selection of polymer composition, solvent, temperature, and pH, the physical characteristics of the micelles can be tuned, providing advantages over low molecular weight surfactants. The self-assembly of micelles in aqueous solvents has great potential in drug delivery and catalyst applications. Understanding how the properties of block copolymer micelles vary in different solvent systems is one step to utilizing the loading capabilities of the micelles in applications. In the present study, two different molecular weight series of diblock copolymers, consisting of a hydrophobic polycaprolactone block and a hydrophilic poly(ethylene oxide) block, were introduced to a solvent mixture of deuterated tetrahydrofuran and deuterated water. The structural properties of the micelles were probed using dynamic light scattering and small angle neutron scattering, as the ratio of THFd8 to D2O in the micelle solutions varied.