pH-Dependence of the morphology of micelles formed by poly(2-vinylpyridine)-block-poly(ethylene oxide) copolymers in water

摘要

The morphology of micelles formed by two poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphate-buffered water by dynamic light scattering and transmission electron microscopy. Spherical micelles are observed when the P2VP block is the minor component of the diblock copolymer. When P2VP dominates the composition, transition from spheres-to-rods-to-vesicles takes place in a narrow pH range that straddles the pKa of P2VP. This transition is controlled by the degree of protonation of the P2VP blocks. At high pH, the copolymer precipitates from the solution.