Effect of nanocellulose fiber hornification on water fraction characteristics and hydroxyl accessibility during dehydration.

Graphical abstract Highlights • We first investigated the hornification of nanocellulose (CNCs, CNF) during dehydration with different solid content. • In order to avoid the effect of drying, liquid AFM mode was carried out in this work. • The different water contents of nanocellulose were quantified by Differential Scanning Calorimetry (DSC). • The amount of free water, freezing bound water, and non-freezing bound water were completely removed in sequence. • The hydroxyl accessibility of both redispersed CNCs and CNF were reduced via evaluating the uptake of fluorescent dyes. Abstract Hornification are usually occurred in cellulosic fibers and even in nanocellulose fibrils during dehydration process but their mesoscopic structural changes is not fully understood. Here we investigated the structural features of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNF) with different solid content. In order to avoid the effect of drying, liquid AFM mode was carried out in this work. The different water contents of nanocellulose were quantified by Differential Scanning Calorimetry (DSC). We showed evidence of extreme growth in radial direction in the redispersed nanocelluloses, analyzed by statistics of contours from microscopy images. The amount of free water, freezing bound water, and non-freezing bound water decreased gradually during water evaporation and were completely removed in sequence. In addition, the hydroxyl accessibility of both redispersed CNCs and CNF were reduced by 83.33% and 81.96% via evaluating the uptake of fluorescent dyes. [ABSTRACT FROM AUTHOR]