Self-Assembly of Amphiphilic Alternating Copolymers by Chain Folding in Water: From Uniform Composition and Sequence to Monodisperse Micelles

Self-assembly systems of amphiphilic copolymers in waterhave beendeveloped to create nano-objects with target structures, properties,and functions, whereas reducing the structural distribution towarduniform self-assemblies is still a challenging issue. Herein, we reportprecision self-assembly of amphiphilic alternating copolymers intomonodisperse micelles via chain folding in water. For this purpose,we synthesized an alternating copolymer bearing hydrophilic poly(ethyleneglycol) (PEG) and hydrophobic dodecyl groups via the radical copolymerizationof PEG methyl ether acrylate (PEGA) in the presence of an excess amountof dodecyl vinyl ether (DVE). The PEGA/DVE alternating copolymersinduced self-folding and intermolecular self-assembly into unimerand multichain micelles, dependent on the degree of polymerization(DP): The aggregation number of the micelles can be controlled bytuning DP, and the copolymers shorter than the threshold DP of 200exclusively formed multichain micelles. Owing to the uniform compositionand monomer sequence, the PEGA/DVE alternating copolymer formed amonodisperse multichain micelle; the apparent size distribution ofthe alternating copolymer micelle was narrower than that of a correspondingacrylate-type random copolymer. Furthermore, the alternating copolymermicelle sharply and reversibly showed lower critical solution temperature-typethermoresponsive solubility in water.