Synthesis of soft-core hard-shell nanoparticles by visible PET-RAFT polymerization in dispersion conditions

Abstract

Photoinduced electron/energy transfer (PET)-RAFT polymerization is an innovative technique for the synthesis of new nanomaterials moving towards greener conditions and process optimization. In the current work, we present a fast, simple, and robust methodology for the synthesis of spherical soft-core hard-shell nanoparticles in a fashionable controlled way. We exploited ZnTPP for the synthesis of poly(dimethyl acrylamide)-b-poly(butyl acrylate) (PDMA-b-PBA) block copolymer in various alcoholic media in dispersion conditions. The use of a homemade photoreactor allows to carry out several reactions simultaneously and to obtain quickly the optimization of the experimental conditions. In all cases, NMR analysis highlights the success of the PDMA-b-PBA polymerizations with very good yield (α > 75%) and low dispersity (Đ < 1.3). Dynamic light scattering (DLS) and TEM microscopy were used to analyze the NPs morphology, which varies from spherical-like shape to more complex second-order structures, depending on the water content of the alcoholic media. In order to improve the particles synthesis, making the process easier to scale up and reducing the use of organic solvents, one-pot polymerization was implemented with promising results. Finally, we demonstrate that a significant amount of photocatalyst is retained in the soft core, feature that can open the door for the production of innovative materials for photophysic applications.