Perhydroxycucurbit[6]uril-induced self-assembly of a double-hydrophilic block copolymer in aqueous solution

We reported the preparation of the poly(N-vinyl pyrrolidone)-b-polyethylene glycol (PVP-b-PEG) double-hydrophilic block copolymer by atom transfer radical polymerization (ATRP). The PVP-b-PEG samples were characterized by nuclear magnetic resonance spectroscopy and Fourier translation infrared spectrum. By taking advantage of its exceptional binding affinity, the perhydroxycucurbit[6]uril ((HO)12CB[6]) was used to interact with PVP-b-PEG by hydrogen bond and constructed micelle-like core–shell aggregates with the physical cross-link PVP segments as the core and the extending PEG chains as the outer palisade. The size of aggregates was about 50–300 nm. The particle size of this type of assemblies could be controlled by the weight content of (HO)12CB[6]. The size distribution was broad at high concentrations. The broad size distribution at high (HO)12CB[6] concentration was due to the coexistence of isolated particles and clusters. These novel micelle-like core–shell aggregates could be controlled by pH value. At pH lower than 6 or pH larger than 13, hydrogen bond interactions were destroyed and the formed (HO)12CB[6]-induced PVP-b-PEG assemblies could be destructed.