Single crystals and oriented crystallization of ivory nut mannan

The preparation of lamellar single crystals of mannan[poly((1 → 4)‐β‐ D ‐mannose)] is described. Electron diffractograms clearly identify the perpendicular orientation of the chain axis with respect to the lamellar surface. Since the degree of polymerization is 40 or less, no conclusion is made as to chain folding. The unit cell corresponds to the mannan I structure derived from x‐ray fiber data on oriented algal mannan. The baseplane dimensions found were a = 7.22 Å and b = 8.92 Å, and the systematic absences observed confirm the proposed P 2 1 2 1 2 1 group. It was found that cellulose microfibrils from Valonia ventricosa and bacterial cellulose could serve as extended chain nuclei for inducing oriented crystallization of mannan on cellulose. This produces a shish‐kebab type of morphology.