Synthesis of fluorinated nanoparticles via RAFT dispersion polymerization-induced self-assembly using fluorinated macro-RAFT agents in supercritical carbon dioxide

A series of poly(dodecafluoroheptyl methacrylate)-b-poly(methyl methacrylate) (PDFMA-b-PMMA) diblock copolymer nanoparticles were prepared by reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of methyl methacrylate (MMA) in supercritical carbon dioxide. Nuclear Magnetic Resonance (NMR) and gel permeation chromatography (GPC) analysis confirmed an efficient and wellcontrolled block copolymerization. As the length of the PMMA block grows from the soluble PDFMA block it eventually becomes insoluble, which drives in situ polymerization-induced self-assembly (PISA). The influences of the length of CO2-philic PDFMA block, CO2-phobic PMMA block and polymerization pressure were investigated in this PISA process. Also spherical nano-objects were formed upon the synthesis of amphiphilic diblock copolymers in situ. It appeared that, as the length of CO2-philic block PDFMA was increased, there was a corresponding decrease in particle size and particle size polydispersity. Scanning electron microscope (SEM) images revealed that, during the microspheres formation, the greater degree of polymerization (DP) of MMA favoured well-controlled monodisperse microspheres.