Orienting Cellulose Nanocrystal Functionalities Tunes the Wettability of Water-Cast Films.

Cellulose nanocrystal (CNC)-based materials display apparently erratic wetting behaviors with contact angle (CA) variations as large as 30° from sample to sample. This work hypothesizes that it is the orientation of CNC amphiphilic functionalities at the interface with air that causes the variability in CA. By exploiting relationships with the Hansen solubility parameter theory, a set of surface tension parameters is proposed for both the polar and the non-polar surfaces of cellulose I nanocrystals.