Multiresponsive Polymer Assemblies Achieved by a Subtle Chain Terminal Modification

Inspired by the influence of chemical structure of end groups on the phase transition temperature of thermoresponsive polymers, we demonstrated a strategy to control the multi-responsiveness of polymer assemblies via subtle modification of end groups of thermoresponsive polymer segments and revealed its potential application for drug delivery. By developing polymer assemblies composed of poly(aliphatic ester) as the inner core and thermoresponsive polyphosphoester as the outer shell, we showed that end groups of thermoresponsive polyphosphoester segments controlled the surface property of assemblies and further determined the stimuli-responsive behavior. The phase-transition temperatures of the unmodified polymer assemblies are tightly controlled by their surface properties due to the hydrophilic to hydrophobic transitions of end groups in response to an environmental stimulus (e.g. pH or light irradiation). External control over these surface properties can by asserted by adjusting the chemical structure and composition of the terminal groups of the thermoresponsive polyphosphoesters.