Fig. 1. Schematic illustration for the preparation of GO-TRITT (a),FTIR spectrum of GO (b),XPS spectra of GO,GO-NH₂ and GO-TRITT (c) (the inset is the magnified XPS spectrum of GO-TRITT); high resolution spectrum of S 2p of GO-TRITT (d)

Fig. 2. Digital photos of the GO dispersion after radiation grafting polymerization of NIPAAm with the addition of Fe²⁺ (rGO-g-PNIPAAm-9) (a) and TRITT (rGO-g-PNIPAAm-5) (b) in the solution

Fig. 3. TEM images of GO (a),GO-NH₂ (b),GO-TRITT (c),and rGO-g-PNIPAAm (d)

Fig. 4. Raman spectra (a) of rGO-g-PNIPAAm prepared with different absorbed doses and ¹H NMR spectra (b) of TRITT,and homo-PNIPAAm in the grafting solution of rGO-g-PNIPAAm（color online）

Fig. 5. Transient absorption spectra of Ar-saturated aqueous solution containing NIPAAm (10 mmol/L) and TRITT (27.4 μmol/L) (a),as well as TRITT only (27.4 μmol/L) (b) after irradiation by pulsed electron beam; evolution of the absorbance at 380 nm and 410 nm of Fig.5(a) (c) (color online)

Fig. 6. Evolution of the absorbance at 720 nm of the Ar-saturated aqueous solution containing tert-butanol (0.5 mol/L) and different concentrations of NIPAAm (a); calculation of the reaction rate constant between NIPAAm and e_aq^- by linear fitting (b); structure of the reaction products between NIPAAm and e_aq^- (c); evolution of the absorbance at 472 nm of the N₂O-saturated aqueous solution containing different concentrations of KSCN (0.1~0.5 mmol/L) and NIPAAm (d); calculation of the reaction rate constant between NIPAAm and OH by linear fitting (e); structures of the products between NIPAAm and OH (f)（color online）

Fig. 7. ζ potentials of rGO-g-PNIPAAm-5 at different pH ((a),25 ℃) and temperatures ((b),pH 4 and 6)

Fig. 8. Time-dependent temperature (a) and digital photos (b) of the solution containing different concentrations of rGO-g-PNIPAAm-5 under irradiation by 808-nm NIR LASER,and time-dependent temperature (c) of the solution containing rGO-g-PNIPAAm with different absorbed doses for radiation grafting polymerization under irradiation by 808 nm NIR LASER（color online）

Fig. 9. Evaluation of the reusability (a) and TEM image (b) of rGO-g-PNIPAAm-5 after irradiation by 808-nm NIR LASER

Table 1. Recipes of the preparation of different rGO-g-PNIPAAm

Table 2. Atomic ratios of different elements in various rGO-g-PNIPAAms