STABILITY OF CELLULOSE STRUCTURES STUDIED BY MD SIMULATIONS - COULD MERCERIZED CELLULOSE-II BE PARALLEL

By extensive and systematic molecular dynamics simulations eight stabl e cellulose crystal structures have been identified. mie organized the m in a coherent scheme, which gives a clue to possible interconversion s between the various structures. From this scheme it can be inferred that mercerized cellulose II could in fact be a parallel structure or contain parallel regions. This parallel cellulose II structure fits in to the same unit cell dimensions as antiparallel cellulose II and ther efore can remain unnoticed. Regenerated cellulose II is likely to have all hydroxymethyl groups in the gt conformation similar to what was f ound in two recent determinations of the cellotetraose structures. Due to its characteristic layer structure cellulose I could crystallize i n several different packing modes. Biosynthesis, however, enforces a p arallel packing. It is shown that I alpha and I beta have a similar an d specific parallel packing mode.