Use of Polyion Complexation for Polymerization-Induced Self-Assembly in Water under Visible Light Irradiation at 25 °C

Polyion complexation (PIC) as the driving force of polymerization-induced self-assembly (PISA), that is, PIC-PISA, is explored. Reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of NH3+-monomer 2-aminoethylacrylamide hydrochloride (AEAM) can be achieved in water under visible light irradiation at 25 degrees C, using nonionic poly2-hydroxypropylmethacrylamide (PHPMA) macromolecular chain transfer agent in the presence of anionic poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS) PIC-template. Sphere-to-network transition occurs, owing to the PIC of PAMPS with growing chains upon reaction close to isoelectric point (IEP); thereafter, the increase of electrostatic repulsion promotes the split of networks and the rupture of spheres into fragments. Therefore, the free-flowing solution becomes viscous liquid and free-standing physical gel, and then back into viscous and free-flowing liquid. Such a PIC-PISA is appealing for gene delivery because the size and surface charge are variable on demand and at high solids.