Room temperature synthesis of poly(poly(ethylene glycol) methyl ether methacrylate)-based diblock copolymer nano-objects via Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA)

The photoinitiated polymerization-induced self-assembly (photo-PISA) of 2-hydroxypropyl methacrylate (HPMA) is conducted in water by using poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) based macro-RAFT agents. Polymerizations were carried out at room temperature via exposure to visible light irradiation, and quantitative monomer conversions (> 99%) were achieved within 30 min of visible light irradiation. A remarkably diverse set of complex morphologies (spheres, worms, and vesicles) have been prepared by aqueous photo-PISA under mild conditions (water medium, room temperature, and visible light). The morphology of nano-objects can be tuned by changing the reaction parameters (e.g. degree of polymerization, solids concentration), and two detailed phase diagrams were constructed. The polymerization can be activated or deactivated by a simple "ON/OFF" switch of the light source. A thermo-responsive behavior of PPEGMA14-PHPMA200 nanoparticles prepared at 15% w/w was investigated by changing the temperature from 25 degrees C to 4 degrees C.