Stepwise self-assembly of a block copolymer-platinum(ii) complex hybrid in solvents of variable quality: from worm-like micelles to free-standing sheets to vesicle-like nanostructures.

Abstract

The self-assembly process of formation of worm-like micelles of a block copolymer-platinum(ii) complex hybrid is investigated with respect to the influence of solvent quality. When the solvent quality is moderately weakened, unilamellar free-standing sheets are achieved, in which the worm-like micelles snap off to form star micelles together with a few short worms. Extremely worsened solvent quality leads to unilamellar vesicle-like nanostructures, onto which only star micelles emerged. With the intermediate solvent quality, the sheets coexist with the vesicle-like nanostructures. This is well correlated with mechanistic insights regarding the morphological transition from sheet- to vesicle-like nanoassemblies. In these aggregates, short worms and star micelles still hold their core-shell structures. Furthermore, these unconventional superstructures are well interrelated with their luminescence properties. This result challenges the conventional paradigm of the amphiphilic self-assembly of surfactants and block copolymers in selective solvents, where they form bilayered nanostructures and are required universally to be rearranged during the morphological transition from micelles to vesicles.