Hydrogen-Bonding UCST-Thermosensitive Nanogels by Direct Photo-RAFT Polymerization-Induced Self-Assembly in Aqueous Dispersion
Résumé
Hydrogen-bonding upper critical solution temperature (UCST) thermosensitive nanogels based on poly(N-acryloyl glycinamide) (PNAGA) are synthesized by photo-reversible addition-fragmentation chain transfer mediated polymerization-induced self-assembly (photo-RAFT PISA) in aqueous dispersion using N,N′-methylenebis(acrylamide) as crosslinker and poly(oligo(ethylene glycol) methyl ether acrylate) as both stabilizer and macromolecular chain
transfer agent (macro-CTA). Highly stable, spherical nanogels with narrow polydispersity are efficiently produced up to complete monomer conversion within 1 h under UV irradiation at low temperature (3 °C). The thermosensitive
behavior of PNAGA-based nanogels, as assessed by dynamic light scattering and UV–vis spectrophotometry, exhibits reversible heating-induced swelling and cooling-induced shrinking corresponding to the expected UCST behavior.
The hydrodynamic diameter, swelling ratio, and phase transition temperature of nanogels can be tuned by modifying the initial molar ratio of monomer-tomacro-CTA and the amount of crosslinker in the photo-RAFT PISA of NAGA