Self-Assembly of Polyoxometalate-Based Starlike Polymers in Solvents of Variable Quality: From Free-Standing Sheet to Vesicle
2014
Liao, Yin | Liu, Nijuan | Zhang, Qian | Bu, Weifeng
Polyoxometalate-based supramolecular star polymers, where an anionic polyoxometalate is closely encapsulated by a hydrophobic shell of cation terminated polystyrenes, are conceptually regarded as a model of star polymers to study their intra- and interstar interactions and self-assembled behaviors in solvents of variable quality. These model stars can self-assemble to form unilamellar free-standing sheets in the toluene/methanol mixture solvent with a methanol volume ratio of 50%. An increase in the methanol content to 75% or 80% results in a coexistence of free-standing sheets with vesicles, where several intermediates are captured for the morphological evolution from sheet to vesicle. With further increasing methanol content to 90%, pure vesicle phases form with unilamellar or oligolamellar features. All these aggregates are packed by the totally hydrophobic starlike polymers, where the core–shell structures are retained. This is distinctly different from the bilayered nanostructures formed by amphiphiles such as surfactants and block copolymers in selective solvents.
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