Organized Polymeric Submicron Particles via Self-Assembly and Cross-Linking of Double Hydrophilic Poly(ethylene oxide)‑b‑poly(N‑vinylpyrrolidone) in Aqueous Solution

The formation of submicron particles consisting of double hydrophilic diblock copolymers of poly­(ethylene oxide) and poly­(N-vinylpyrrolidone) (PEO-b-PVP) in aqueous solution is described. Block copolymers were synthesized via reversible deactivation radical polymerization using a PEO-xanthate as macro RAFT/MADIX chain transfer agent. Increasing polymer concentrations in aqueous solutions, the block copolymer is able to self-assemble into spherical structures with apparent hydrodynamic diameters in the range between 200 nm and 2 μm. The self-assembly was further improved by copolymerization with a more hydrophilic monomer, N-vinylimidazole (VIm). Submicron particles from PEO-b-P­(VP-co-VIm) were preserved via cross-linking utilizing imidazolium formation with a dihalogenide. Thus, submicron double hydrophilic particles were obtained that are stable in organic solvents and under high dilution. Almost quantitative formation of submicron particles with an average diameter of 200 nm can be afforded by the self-assembly in the polar organic solvent DMF and subsequent crosslinking as well. Furthermore, the obtained particles show a promising ability to incorporate various molecules for delivery and release, here exemplified with simple dyes.