Figure 23.
Application of methods to measure surface energy and mass transport in investigating nanocellulose–water interactions. (a) The operating principle of sessile drop goniometry.1022 (b) A liquid droplet on a nonideal solid surface: (i) apparent and real contact angles on a rough surface, (ii) apparent and real contact angles on a heterogeneous surface.1029 (a,b) Adapted with permission from ref (1029). Copyright 2018 Springer Nature. (c,d) Comparison of the dispersion component of surface energies of CNFs dried with different methods: (c) CNFs and (d) CNCs.255 (c,d) Adapted with permission from ref (255). Copyright 2013 Elsevier. (e,f) Water vapor uptake studies to investigate the effect of surface modification: (e) Water vapor uptake isotherms of the initial and C14-modified CNF films (black squares and red circles, respectively), plotted together with data from comparable CNF samples. (f) The qualitative difference in wetting behavior of the two film types 20 s after being exposed to methylene blue dyed water droplets. The hydrophobic C14-modified film is on the left, the untreated control film is on the right.297 (e,f) Adapted with permission from ref (297). Copyright 2017 Springer Nature. (g) Permeation of water under ambient pressure and at room temperature for unmodified CNF nanopapers and modified CNF nanopapers by hot pressing and lignin content. Hot pressing and lignin reduce the permeation of water in ambient conditions, significantly.1021 (g) Adapted under the terms of CC-BY from ref (1021). Copyright 2019 American Chemical Society. (h) Water flux of fabricated support layers for enhanced adsorption of metal ions with and without sludge microfibers/cellulose nanofibers (CNFSL). Layered fabricated membranes indicate a decrease in water flux but in situ TEMPO oxidation has no significant effect on water flux.1030 (h) Adapted under the terms of CC-BY from ref (1030). Copyright 2017 The Royal Society of Chemistry.