Contractive polymeric complex micelles as thermo-sensitive nanopumps

Complex micelles were obtained from PS-b-PNIPAM-b-PAA micelles and PEG-b-P4VP block copolymers via the strong electrostatic interaction and hydrogen bonding between PAA and P4VP blocks in water. The PS block formed the core and the PAA/P4VP complex shell functioned as a semi-permeable membrane which could control the permeation of small molecules. Between the core and shell, the large fluid-filled space that was formed with the thermoresponsive PNIPAM gel could retain the loaded drug for a long period of time. With increasing temperature, the shrinkage of the PNIPAM coils pumped the drug out of the complex micelles. The complex micelles functioned as a contractive nanopump, which could potentially be applied as a thermosensitive controlled release system.