Temperature-directed micellar morphological transformation using CABC-block copolymers and its applications in encapsulation and hidden segment

Abstract

A temperature-directed micellar morphological transformation was developed using CABC multi-block copolymers with a hydrophobic block A, a hydrophilic block B, and a thermally responsive block C with a lower critical solution temperature (LCST). The micellar structure was switched from a star (below LCST) to a flower (above LCST). The transition temperature was tunable in a wide range (11-90 °C) by varying the C monomer composition. The large difference in the loading capacity between the star and flower enabled efficient encapsulation and controlled release of external molecules. Unlike conventional systems, the present star-to-flower transformation keeps micellar structures and hence does not liberate polymers but only external molecules selectively. Another application is a hidden functional segment. A functional segment is hidden (shielded) below the LCST and exposed to interact with external molecules or surfaces above the LCST.