Visible-Light-Driven PET-RAFT Emulsion PISA of Biobased Graft Copolymers Toward Spherical Nanoparticle Formulation

We report the formulation of dextran-based nano-objects via polymerization-induced self-assembly (PISA) in aqueous emulsion, using photoinduced electron/energy transfer RAFT (PET-RAFT) polymerization under visible light irradiation (λ = 500 nm). A dextran macromolecular chain transfer agent (DexCTA), bearing multiple trithiocarbonate groups, was employed as a hydrophilic scaffold for the grafting of poly(methyl methacrylate) (PMMA) chains. Eosin Y was used as a metal-free photocatalyst to mediate polymerization in water under mild conditions. By systematically varying the PMMA graft degree of polymerization (X = 100-400) and solids content (5-15% w/w), we investigated the influence of formulation parameters on nanoparticle morphology and size. High monomer conversion (>99%) was achieved within 2 h of irradiation. Transmission electron microscopy revealed spherical morphologies across all conditions, with increasing particle size as a function of X and solids content. This study highlights the potential of PET-RAFT emulsion PISA as a green and versatile strategy for the design of polymeric nanomaterials.