Influence of substituent of direct dye having bisphenylenebis(azo) skeletal structure on structure of nascent cellulose produced by Acetobacter xylinum .1. Different influence of Direct Red 28, Blue 1 and 15 on nascent structure

The difference of influence of a certain kind of direct dye on the structure of nascent microbial cellulose was examined, with Direct Red 28 having a biphenylenebis(azo) skeletal structure; Direct Blue 1 having two hydroxyl, two methoxy and two sulfonate groups more than Direct Red 28; and Direct Blue 15 whose sulfonate groups position are different compared to Direct Blue 1. It became clear that the product in the presence of a direct dye (in particular, Direct Red 28) has the structure in which the dye molecule is included between the monolayer in the cellulose sheets corresponding to the (1(1) over bar0$) plane of microbial cellulose. On the other hand, the structure of the product in the presence of Direct Blue 1 and 15 contains conceived cellulose II structure which occurred due to be removal of dye during the rinsing process as a result of larger hydrophilicity than its affinity toward cellulose. Solid state C-13 NMR and deuteration-IR measurements showed that the product in the presence of direct dye is in a noncrystalline state, although X-ray measurements indicated that they are in a crystalline state. These results support the inclusion of a dye between the (1(1) over bar0$) planes. Solid state C-13 NMR and deuteration-IR reveal that the crystal structure of cellulose regenerated from the product in the presence of Direct Red 28 is similar to cellulose IVI, while that from each Direct Blue 1 and 15 product is cellulose II. The difference of the influence of the former and the latter on the nascent cellulose seemed to be caused mainly by the number of sulfonate groups, although the influence of hydroxyl and methoxy groups is not clear at present. (C) 1997 Elsevier Science B.V.