Cellulose precursors high-molecular-weight

When Herman Mark first evaluated the crystal structure of rubber (with E. A. Hauser) and cellulose (with J. R. Katz) in 1924 and 1925, it was generally accepted that these materials were low molecular weight or monomeric. The unusual properties of these substances, now known to be related to high molecular weight, were then attributed to aggolomeration or "association" of the low molecular weight precursors. A common explanation for the associations were secondary forces such as Johannes Thiele s partial valences. 

Possible Involvement of High-molecular-weight Precursors to Cellulose. 135... 

In addition to the suggested, but not proved, role for lipid intermediates, much speculation has appeared on the possibility that there may also exist some sort of high-molecular-weight precursor to cellulose. Here again, suggestive evidence exists for such a polymer, but conclusive proof of its existence is still lacking. 

Electron-microscope investigation of cultures of bacteria has shown that the cellulose elements are not a physical appendage of the cell, but occur free and are scattered within the medium.This discovery has raised questions as to the processes or steps involved in the formation of the microfibrils and the extent to which they are influenced by cell organelles or carried out by exogenous chemical interactions and mechanical forces. Ohad and coworkers considered that the steps involved may be resolved into (a) polymerization of the activated, monomeric precursor to form cellulose molecules of high molecular weight, (b) transport of the molecule from the site of synthesis to that of crystallization, (c) crystallization or fibril formation, and (d) orientation of fibrils during deposition. 

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