Microscopic Visualization of Nanostructures of Cellulose Derivatives

Microscopy has proved to be a valuable tool for the investigation of supermolecular structures of cellulose derivatives. Thus, with AFM it was possible to show that statistically functionalized derivatives (degree of substitution below 3) form specific aggregates called fringed micelles. In contrast, derivatives with a non-statistic distribution exhibit a more network-like structure as known for galactomannans consisting of block-like structures. If samples are prepared by deposition of dilute solutions of polyelectrolytes on mica and drying at elevated temperature, the formation of nanorings is observed. In addition, AFM and REM were applied to investigate the morphology of membranes prepared of cellulose esters with unsaturated substituents. It was shown that cross-linking of the polymer chains in the membranes does not lead to a change in the nanostructure of the surface, i.g., the surface roughness and the pore sizes were not modified.