Folded amphiphilic homopolymer micelles in water: uniform self-assembly beyond amphiphilic random copolymers

Abstract

Herein, we developed precision self-assembly systems of amphiphilic homopolymers into folded micelles in water. For this, we newly designed amphiphilic double brush monomers comprising hydrophilic poly(ethylene oxide) (PEG) and hydrophobic alkyl pendants (dodecyl, octyl, and butyl groups). The homopolymers of the monomers carry amphiphilic double brush pendants in all repeating units without hydrophilic/hydrophobic composition distribution. Those homopolymers induced self-folding and intermolecular self-assembly in water, dependent on the alkyl groups, to form unimer and multichain micelles. The homopolymers bearing octyl or dodecyl groups gave uniform micelles; the uniformness was close to that of proteins and better than that of amphiphilic random copolymer micelles. In contrast, the homopolymers carrying butyl groups formed unimer micelles with the original molecular weight distribution. Additionally, those homopolymer micelles showed lower critical solution temperature-type solubility in water. Thus, by designing the pendants, amphiphilic homopolymers opened new ways to create folded and thermoresponsive micelles with uniformness and size controllability beyond amphiphilic random copolymers.