Avicel PH 101, aniline, 4‐pentylaniline, 4‐octylaniline, 4‐[(N‐Boc)aminomethyl]aniline, 4‐trifluoromethyl aniline, anhydrous LiCl, and anhydrous N,N‐dimethylacetamide were obtained from Sigma–Aldrich (St. Louis, MO, USA). ortho‐Dichlorobenzene, tert‐butyl nitrite (isoamyl nitrite), 1,4‐dioxane, 4‐ethylaniline, 4‐ethynylaniline, l‐ascorbic acid, N,N‐dimethylformamide, trimethylsilyl azide, ethylenediaminetetraacetic acid, N‐bromosuccinimide, triphenylphosphine, propionic anhydride, sodium azide, and tetrabutylammonium hexafluorophosphate were supplied by Tokyo Chemicals Industry Co., Ltd. (Tokyo, Japan). Acetonitrile and hydrochloric acid were purchased from Naclai Tesque, Inc. (Kyoto, Japan). All other chemicals were from Kanto Chemical (Tokyo, Japan).
Carbon fiber T700SC‐12000‐50C was provided by Toray Industries (Tokyo, Japan) with the following specifications: diameter, 7 μm; tensile strength, 4900 MPa; sizing agent, 1 % of the total mass. The fibers were cleaned before the experiments to remove the sizing agent and impurities from the surface according to our previous report.25 The cleaning procedure included ultrasonic washing in acetone (2×) for 20 min at 40 °C, followed by rinsing with methanol and water, and ending with drying in a vacuum oven (ADP 200, Yamato Scientific Co., Ltd, Tokyo, Japan) at 150 °C for 3 h. The carbon fibers were stored in sealed vials, and before use, they were cleaned in an ultrasonic bath with acetone (5×) for 10 min; the solvent was changed after each step. The removal of the sizing agent was confirmed by TGA, XPS, and AFM measurements in our previous study.25Cellulose propionate (Mw≈200000 g mol−1) was supplied by Scientific Polymer Products, Inc. (Ontario, NY, USA) and was used as received for the matrix of the composite. The degree of substitution (DS) value was determined to be 2.76 by using the benzoylation method according to a previous study.36