Fluorescent and thermo-responsive cellulose nanocrystals (CNCs) were synthesized via surface-initiated single-electron transfer living radical polymerization (SI-SET-LRP) in the component solvent system of DMF/H2O.The grafting of poly (N-isopropylacryalamide) (PNIPAAM) brushes on CNCS was confirmed and analyzed by Fourier transform infrared spectroscopy

solid-state 13C nuclear magnetic resonance spectrometry and transmission electron microscopy.The initiator immobilization and subsequent grafting polymerization were proven to be limited on the surface of CNCs without the change of core.Grafted brushes with molecular weight in the range of 1500 and 13000 and relatively low polydispersity index were synthesized.Both the conversion of monomer and the molecular weight of polymer brushes increase with an increase in the H2O proportion of the solvent system.The change trend of decomposition and glass transition temperature from low to high temperature direction also proved the increasing length of brushes.The surface-grafted CNCs possessed good dispersity and stability in water because of the hydrophilicity of CNCs and the grafted PNIPAAM at room temperature.They showed reversible state conversion between dispersion and coagulation upon temperature shift around the lower critical solution temperature (LCST).The fluorescent intensity of the surface-grafted CNCs increases as the length of polymer brushes increases.They also showed thermo-enhanced fluorescence based on the thermo-responsiveness of the grafted PNIPAAM brushes.