Characterization
Fourier transform infrared (FT-IR) spectroscopy was employed. For the measurements, the dried
samples were mixed with KBr (about 2 mg sample in 200 mg KBr) and pressed into pellets. The
measurement was performed in a Thermo Nicolet AntarisⅡspectrometer. The spectra were
recorded using a spectral width ranging from 400 to 4000 cm–1
, with a spectral resolution of 4 cm–
1 and an accumulation of 32 scans. The nuclear magnetic resonance (NMR) spectrum was
recorded on a Bruker AVⅢ 400 spectrometer operating at 400 MHz. The test tube was filled up
with solid samples, and then the solid-state 13C NMR studies were carried out under ambient
conditions. For the small molecules, the normal liquid-state 13C NMR detection was performed
with a Bruker AscendTM 400WB spectrometer operating at 400 MHz with d
6
-DMSO used as the
solvent. The X-ray photoelectron spectroscopy (XPS) measurements were performed on freezedried
samples of cellulose before and after CAB modifications with an ESCALAB250 electron
spectrometer (ThermoFisher Scientific, USA) and monochromatic Al irradiation at 200 eV for
survey and 150 W power at anode. The crystallinity of cellulose before and after borneol grafting
was measured by X-ray diffraction (XRD) using Cu Ka (0.15418 nm) radiation. The XRD patterns
were recorded on D/Max 2500 VB2+/PC in the range of 2θ=5–90°. Hitachi S-4700 scanning
electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) analysis
system was used to study the chemical composition of the samples.