Synthesis of Highly Transparent Diblock Copolymer Vesicles via RAFT Dispersion Polymerization of 2,2,2-Trifluoroethyl Methacrylate in <i>n</i>-Alkanes

RAFT dispersion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) is performed in n-dodecane at 90 °C using a relatively short poly(stearyl methacrylate) (PSMA) precursor and 2-cyano-2-propyl dithiobenzoate (CPDB). The growing insoluble poly(2,2,2-trifluoroethyl (PTFEMA) block results the formation PSMA–PTFEMA diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). GPC analysis indicated narrow molecular weight distributions (Mw/Mn ≤ 1.34) for all copolymers, with 19F NMR studies indicating high TFEMA conversions (≥95%) syntheses. A pseudo-phase diagram was constructed to enable reproducible targeting pure spheres, worms, or vesicles by varying target degree PTFEMA 15–25% w/w solids. Nano-objects were characterized dynamic light scattering, transmission electron microscopy, small-angle X-ray scattering. Importantly, near-identical refractive indices (1.418) (1.421) first example highly transparent be prepared. turbidity such dispersions examined between 20 °C. highest transmittance (97% 600 nm) observed PSMA9–PTFEMA294 (237 ± 24 nm diameter; prepared 25% solids) Interestingly, same composition n-hexadecane produced vesicle minimal synthesis temperature This solvent enabled situ visible absorption spectra recorded during PSMA16–PTFEMA86 spheres 15% solids, which allowed weak n→π* band 515 assigned chain-ends monitored. Unfortunately, premature loss this chain-end occurred °C, so meaningful kinetic data could not obtained. Furthermore, exhibited λmax shift 8 relative that dithiobenzoate-capped PSMA9 precursor. solvatochromatic effect suggests problem thermally labile cannot addressed performing lower temperatures.