2.3.1. Fourier Transform Infrared Spectroscopy (FTIR)

FTIR spectra of pristine spray dried sulfated CNCs and lyophilized esterified and cationic CNCs were recorded on a PerkinElmer FTIR spectrophotometer (Spectrum Two) (Norwalk, CT, USA) at room temperature. KBr pellets were prepared by grinding in a mortar and compressing about 2% of the CNC samples in KBr (previously well-dried in an oven). Background measurement using a neat KBr pellet was first obtained to correct for light scattering losses in the pellet and any water absorbed by KBr. Spectra in the range of 4000–400 cm−<sup>1</sup> were obtained with a resolution of 4 cm−<sup>1</sup> by cumulating 32 scans.
