Preparation of Responsive Zwitterionic Diblock Copolymers Containing Phosphate and Phosphonate Groups

In this study, novel zwitterionic diblock copolymers, namely poly(2-(N-morpholino)ethyl methacrylate))-block-poly(2-(methacryloyloxy)ethyl phosphate) (PMEMA-b-PMOEP) and poly(2-(N-morpholino)ethyl methacrylate))-block-poly ((methacryloyloxy)methyl phosphonic acid) (PMEMA-b-PMOMP), were synthesized via reversible addition-fragmentation chain transfer controlled radical polymerization. Solution properties of these phosphorus-based diblock copolymers were investigated using dynamic light scattering, transmission electron microscopy and proton nuclear magnetic resonance spectroscopy. Since the PMEMA block has both salt- and thermo-responsive properties, PMEMA-b-PMOEP and PMEMA-b-PMOMP diblock copolymers formed core-shell micelles in basic aqueous media as the PMEMA block formed insoluble micelle core with the addition of Na2SO4 or an increase in temperature in basic solution. Additionally, PMEMA-b-PMOMP diblock copolymers interacted strongly with calcium cations and yielded reverse micellar structures via complexation of phosphate with metal cation in aqueous media.