´Schizophrenic´ micellisation of poly(acrylic acid)-b-poly(2-dimethylamino)ethyl methacrylate: From spherical to worm-like micelles

The well-defined block copolymer poly(acrylic acid)-6-poly(2-dimethylamino)ethyl methacrylate (PAA-i-PDMAEMA) was synthesised by sequential atom transfer radical polymerisation using protected group chemistry. The block copolymers exhibit the so-called ´schizophrenic´ micellisation behaviour at different pH values. The PAA-core micelles and PDMAEMA-core micelles were formed in acidic pH (pH = 3.4) and basic pH (pH = 9.2), respectively. Different morphologies of ´schizophrenic´ block copolymer particles: spherical micelles and worm-like reverse micelles were observed by transmission electron microscope and the ratio of gyration radius (R_g) to hydrodynamic radius (R_b).