Meyer-Misch structure

Cellulose I is natural cellulose as found in cotton, wood, and Valonia. Although the Meyer and Misch structure (unit-cell dimensions a = 8.35,... 

Natural cellulose is now referred to as cellulose I. Cellulose 11 is obtained from cellulose I by the mercerization process, i.e., soaking and wash out with aqueous NaOH. The crystal structure of cellulose is shown in Fig. 1.20. Later researches have proposed variant crystal structures of cellulose (cellulose I [118], cellulose II [119, 120], and indeed a cellulose III [121], and cellulose IV [122]) different from the Meyer-Misch model. 

Figure 1.20 Crystal structure of (a) cellulose I (Meyer-Misch model) and (b) cellulose II...

In Geneva, he resumed with new energy his studies of macromolecules. He was able to obtain the cooperation of A. J. H. van der Wijk, who was one of his most devoted coworkers the latter s realistic criticisms were a valuable balance to Meyer s great enthusiasm. Studies on the thermodynamics of large molecules in solution, and on the structure of cellulose and chitin, were pursued with C. Boissonnas, W. Lothmar, and L. Misch. A theory of the elasticity of rubber evolved from his work with C. Ferri and his previous observations with Susich and Valk6. 

The constitutional formula and molecular weight of cellulose determined on the basis of chemical and physico-chemical experiments has been confirmed by X-ray analysis, which has also led to the discovery of the microcrystalline structure of cellulose. Today the structural model proposed by Meyer and Mark [21] and Mark and Misch [22] based on the X-ray measurements of Polanyi [23] and Sponsler and Dore [24] and taking into consideration Haworth s conclusions about the existence... 

Monoclinic unit cell of cellulose I according to the model by Meyer and Misch [37], which shows the antiparallel orientation of adjacent chains (left) and the hydrogen-bonding network of two adjacent cellulose chains forming a sheet-like structure according to Gardner and Blackwell [38]... 

Typically, this approach leads to a large number of possible structures, because Jones allowed both the 0-3 -0-5 and 0-2-0-6 type of intra molecular hydrogen bond. Comparison of the most plausible structures for cellulose I and II with observed equatorial and meridional intensity led Jones to conclude that several structures, including that of Meyer and Misch, are fair approximations to the actual structure, but none of them show especially good agreement with the x-ray intensities observed. As a possible solution, Jones suggested a statistical structure, in which there is randomness of chain polarity, but in which adjacent chains have one characteristic shift along the b axis when they have parallel orientation, and a different one for the antiparallel situation. 

T,he chemical structure of cellulose chains was established by Haworth and Hibbert more than 40 years ago. Native cellulose occurs in solid state and in partly crystalline form. A schematic model for the native cellulose lattice was worked out about 1930 by Meyer, Mark, and Misch. The basic morphology of native cellulose could not be resolved, however, before electron microscopy with high resolution was developed and applied. During the last two decades, it has been amply shown and is now generally accepted that native cellulose basically is composed of microfibrils of a width 100 A. or less as was reviewed in 1956 (12). 

The structure later proposed by Meyer and Misch (22) was based on the reasoning that the rapidity of mercerization, and its occurrence without dissolution required that the polarity of the chains be the same in both celluloses I and II. It was reasoned further that regeneration of cellulose from solution is most likely to result in precipitation in an antiparallel form, and that the similarity between x-ray diffraction patterns of mercerized and regenerated cellulose required that they have the saae polarity. It was thus inferred that native cellulose must also have an antiparallel structure. 

The most recent investigations on the crystal structure of cellulose are those by Meyer and Misch, Gross and Clark, Kiessig, Kubo, Schiebold and Peirce. ... 

Another class of polymers that occupied 165 pages in the book and many years of effort by Meyer and his collaborators is the celluloses. The detailed X-ray crystallography that resolved the local and mesoscopic structure of cellulose and its micelles is presented in detail. His chief collaborators included Herman Mark, J.R. Katz, Michael Polanyi, L. Misch and G. von Susich. A detailed model of the unit cell of native cellulose is given in Fig. 3.13. 

Cellulose is the most plentiful natural polymer on earth. Studies of structure of cellulose goes back as early as 1839 well before the development of X-ray diffraction. After the coming of X-ray diffraction in the years following 1912, extensive X-ray diffraction studies of cellulose were reported. Various researchers have proposed models of the crystal structure dating from the 1920s. Sponsler and Dore [115] proposed a unit cell as early as 1926. Different crystal structures were proposed by Meyer and Mark [ 116] in 1928 and by Meyer and Misch [ 117] in 1937. Meyer and Misch [117] reported a new crystallographic model of cellulose that is monoclinic, a = 8.35 A, b = 10.38 A, c = 7.95 A, p = 84°. Cellulose today is considered to be polymorphic and to have a (triclinic) and p (monocHnic) forms. 

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