Amphiphilic macromolecular nanostructure materials derived from 5-(octanoate methyl)bicyclo[2.2.1]hept-2-ene and 5-(phthalimide methyl)bicyclo[2.2.1]hept-2-ene via ring-opening metathesis copolymerization

Novel highly stable polynorbornenes with self-assembling amphiphilic architecture containing hydrophilic ammonium salt and hydrophobic alkyl ester group were obtained via ring-opening metathesis polymerization (ROMP) of 5-(octanoate methyl)bicyclo[2.2.1]hept-2-ene (NBMO) and 5-(phthalimide methyl)bicyclo[2.2.1]hept-2-ene (NBMPI), hydrogenation, hydrazinolysis, and subsequent quaternization. Polymeric micelles of such amphiphilic random and block polynorbornenes formed in solvents by varying the content of ammonium salts were investigated. Amphiphilic block copolymers exhibited perfect spherical morphology. Nanoscale polymeric micelles of random copolymers with 50-75 mol% of ammonium salts were roughly spherical in shape, while the morphologies of micelles transferred into network-like aggregates as hydrophilic contents of the random copolymers are higher than 80 mol%. The formation and fine structures of micelles were investigated by dynamic light scattering (DLS), TEM, and fluorescence technique using pyrene as fluorescence probe.