One-Pot Synthesis for Biocompatible Amphiphilic Hyperbranched Polyurea Micelles

Here we report, for the first time to our knowledge, a method to synthesize AB(2) monomers, the corresponding hyperbranched and the corresponding amphiphilic hyperbranched polymers in a one-pot procedure, starting from two commercial available compounds. Since the B groups were blocked isocyanates (BIs), the end groups of the hyperbranched polyurea were BIs as well. Coupling of a range of monomethoxy-poly(ethylene glycol)s onto the BIs yielded a platform of arnphiphilic hyperbranched polymers, with controllable hydrophobic cores and hydrophilic shells. After the three consecutive reaction steps, without intermediate purification, the final polymers were purified by precipitation in a nonsolvent, in which the polymer precipitated and the excess PEG remained dissolved. Pyrene inclusion experiments showed the formation of micelles above a critical concentration. Both cryo-EM and DLS revealed the presence of two distinct particle populations, being the primary micelles and aggregates thereof All micelles showed a LCST behavior, with transitions close to body temperature. The low cytotoxicity of the micelles make them promising for drug delivery.