Effect of Cellulose Substrate on Assembly of Xylans

Abstract

Cellulosic materials with various specific surface areas, crystallinity and morphology were autoclave treated in solutions of 4-O-methyl glucuronoxylan isolated from birch by alkali extraction. Treatment resulted in "decoration" of the cellulose surfaces with particle-like xylan assemblies of various sizes. The amount of xylan retained on the cellulose was proportional to the accessible surface area of the cellulose substrate as determined by adsorption of the dye Congo Red. Visualization of xylan treated cellulose substrates by immunolabelling and confocal laser microscopy showed that the xylan retained was located not only on the surfaces but also in pores. Formation of xylan surface assemblies was dependent on the cellulose substrate morphology. Fibril-like cellulose I surfaces induce the organization of xylan molecules into globular shaped structures, while the cellulose II surfaces result in formation of less well-defined and more elongated xylan structures. This study shows that treatment of cellulose with glucuronoxylans is a convenient way to modify the surface morphology of cellulose