Amphiphilic random methacrylate copolymers, consisting of poly (ethylene glycol)(PEG) and alkyl pendent groups, undergo reversible single-chain self-folding in water via intramolecular hydrophobic interaction, to generate a dynamic unimolecular hydrophobic nanospace, similar in shape but structurally different relative to micelles and microgel star polymers. These copolymers were prepared by the ruthenium-catalyzed living radical ...