Core-corona nanoparticles formed by high molecular weight poly(ethylene oxide)-b-poly(alkylglycidyl ether) diblock copolymers

Novel high molecular weight poly(ethylene oxide)-b-poly(alkylglycidyl ether) diblock copolymers have been synthesized by sequential anionic-coordination polymerization using a calcium amide–alkoxide initiating system. The hydrophobic blocks were formed by polymerization of alkylglycidyl ethers differing in the size of the hydrophobe and the length of the oxyethylene spacer between the terminal hydrophobes and the polymerizable epoxy group. The length of the spacer was 0, 2 or 10 oxyethylene units. The content of the hydrophobic groups in the copolymers was about 2 wt% as determined by 1H NMR and the molecular weights were found to be up to 1.8×106 g/mol by using GPC and SLS. The aqueous solution properties of the copolymers were studied by static fluorescence, static and dynamic light scattering and transmission electron microscopy. The copolymers were found to self-associate in core-corona type particles in a relatively narrow concentration range. The aggregation numbers and the dimensions of the aggregates were determined by a combination of dynamic and static light scattering molecular weights. Core-corona nanoparticles of low aggregation number (3–5) and slightly extended coronae were found to coexist with unassociated macromolecules in the concentration range between the critical aggregation concentration and the overlap concentration. Both particles were visualized by TEM.