*2.1. Materials*

Bleached wood pulp was provided by Nippon Paper Chemicals Co., Ltd. (Tokyo, Japan). 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, C9H18NO), sodium bromide (NaBr), sodium hypochlorite solution (NaClO, 6–14% active chlorine), ammonium persulfate (APS, H8N2O8S2), aniline monomers (ANI, C6H7N), Sodium hydroxide (NaOH), Potassium hydroxide (KOH), polyvinyl alcohol (PVA, *M*<sup>w</sup> = 124,000–186,000 g mol−1, 99% hydrolyzed), sodium tetraborate decahydrate (Borax, Na2B4O7·10H2O, 99.5% purity) were purchased from Aladdin Chemical Reagent Co., Ltd., Shanghai, China. The carbon nanotubes (CNTs) were obtained from Nanotech Port Co., Ltd., Shenzhen, China (the purity >97%; the diameter in the range 10–20 nm; the length in the range 30–100 μm). They were all the analytical grade. Deionized (DI) water was used in all the preparations.
