The investigation of sized cellulose surfaces with scanning probe microscopy techniques

Scanning probe microscopy techniques of lateral force microscopy, pull-off force measurement, and pulsed force mode adhesion imaging were employed to study the micro-scale surface chemistry of cellulose films hydrophobized by treatment with alkenyl succinic anhydride (ASA). Lateral force microscopy showed a monotonic decrease in surface frictional dissipation with increasing sizing level. The distributions of pull-off forces measured over a (1μm)2 area showed a wide range of local adhesion values on all samples, yet disappearance of the highest adhesion sites with increasing level of sizing agent. The pulsed force mode results showed high-resolution adhesion images of cellulose that complemented the pull-off force distribution results. These results indicate that scanning probe microscopy techniques are able to detect the wettability heterogeneity of ASA-sized cellulose with nanometer resolution.