Oxidation of cellulose microfibril segments by alkaline silver nitrate and its relation to the fine structure of cellulose

摘要

AbstractThe oxidation by alkaline silver nitrate of segments (ca 0.1 μ long) of cellulose microfibrils fromAvenacoleoptiles, ramie, bacteria, andValoniahas been followed by electron microscopy. For comparison, chitin microfibrils have been oxidized by the same reagent and observed by the same method. Oxidation proceeds equally at both ends of the segments, as judged by the rate of deposition of colloidal silver. As a consequence of oxidation, dissolution of the ordered array of 1→4β‐polyglucosan chains (or poly‐N‐acetylglucosamine chains) takes place rapidly from both ends, due to Coulomb repulsion between ionized carboxyl groups and/or electrostriction of water molecules about the same groups. The observations are consistent with the assumption that the neighboring chains run in opposite directions in the cellulose microfibril (i.e., with the Meyer‐Misch antiparallel postulate). They are not in agreement with expectations based upon the parallel