Contact Angle Measurements on Smooth Nanocrystalline Cellulose (I) Thin Films

Interactions of cellulose fiber surfaces with water and other liquids depend on surface morphology as well as intrinsic material properties. Smooth nanocrystalline cellulose (I) films can be used as models to study surface phenomena, where the effects of surface morphology and roughness are minimized. Contact angle measurements are particularly sensitive to surface roughness. In this work, we measured the advancing and receding contact angles for water on thin model cellulose (I) and regenerated cellulose (II) films. The advancing and receding contact angles on model cellulose (I) surfaces were lower than on cellulose (II) surfaces, and the contact angle hysteresis was also lower for the smooth model cellulose (I) surfaces prepared from nanocrystal suspensions. The surface free energy was evaluated for the various cellulose surfaces from contact angle measurements.