Single-Step Grafting of a Thermoresponsive RAFT Polymer from Nanocellulose by Radical Decarboxylation

High Resolution Image Download MS PowerPoint Slide The grafting of polymers in a single step from TEMPO-oxidized nanocellulose (TOCN) via controlled radical polymerization is reported here for the first time. Reversible addition–fragmentation chain-transfer (RAFT) polymerization is achieved through silver-mediated radical decarboxylation on the surface of the cellulose fibers in the presence of a RAFT precursor in a primarily water-based mixture. Electrochemical studies were performed to tune the redox properties of the silver–ligand complex and achieve an extremely high monomer conversion and grafting efficiency. This led to the grafting of a thermoresponsive polymer with low dispersity and controlled molecular weight, which in turn allowed for the tuning of the thermal properties of the nanocellulose–polymer composite. SANS analysis of the materials provides a clear model to explain the effect of the polymer molecular weight on the thermoresponsive and gelation properties of PNIPAM- g -CNF, where a lower polymer molecular weight results in an ordered assembly of bundled fibers above the critical temperature.