Primary valence chains

At the same time K. H. Meyer and Mark (69) proposed an important structure for cellulose which is best described as a compromise between the aggregates of the association theory and Standinger s macromolecules. In an extensive paper, they carefully developed the idea of cellulose chains consisting of so called "primary valence chains". They further proposed that the primary valence chains were aggregated by molecular forces such as hydrogen bonding and van der Waal s forces. 

From these considerations there evolved the concept of "primary valence chains" in cellulose, held together in bundles, or micelles (crystallites) by secondary forces, as propounded by Meyer and Mark (5). This view was then extended to encompass other high polymers as well. It should be noted however, that Freudenberg had already proposed a chain structure for cellulose, based on degradation experiments (6). If the micelles were to... 

I do not believe that the introduction of primary valence chains, instead of macromolecules, solves any problem." Staudinger also stated these views publicly (29). 

Mark responded to Staudinger on November 2, 1928. Among other things he wrote, "I am sorry to see from your letter that you feel annoyed by the statements of Professor Meyer. I am convinced that it was the last thing Professor Meyer intended to do. I have, in our joint research and especially in my Hamburg lecture, emphasized the importance of your beautiful work. Introduction of the term, primary valence chain, is very purposeful since it refers to structures which are not identical. . . rather average lengths. If we add this fact to your macromolecules, then both concepts become identical. 

In this paper Staudinger objected to the use of "primary valence chains" and micelles. However, he did not exclude the possibility of molecular associations. Although he denied the possibility of micelles, he discussed crystallites. The crystallites and the micelles of Meyer and Mark were identical. 

The development of the primary-valence chain theory of cellulose polymers was the next and possibly the most important guidepost to complete understanding of cellulose chemistry and to the development of polymer theory in general. This development... 

With these limitations, and by applying the Boltzmann law, we may ascribe to an isolated primary valence chain an entropy... 

If, however, the forces which unite the micro-units are of the order of magnitude of chemical primary valence, then we obtain chains extending throughout the whole crystal, which, in accordance with previous terminology, may be designated primary valence chains. 

If experience gained from layer lattices is. applied to the chain lattices, which are also frequently named fiber lattices, it is to be expected that the cohesion of the primary valence chains will stamp the whole structure and that permutoid reaction will be present to a still higher degree than in layer lattices, because here the strong cohesion due to primary valence acts only in a single direction. We may further assume that the diffraction effects of such primary valence chains will exhibit certain similarities to diffraction phenomena in linear lattices. 

Natural high polymeric compounds, like high molecular weight mixtures, show only reflections corresponding to the intra-molecular periodicity, so that here also primary valence chain lattices are involved. 

If the individual primary valence chains are not in themselves suflS-ciently orientated, then the intra-molecular interferences of the individual fibers may also be blurred or entirely disappear, so that it is impossible to observe any longer a well defined x-ray pattern. 

A specially good example showing how a large group of important compounds can develop all the above described types—primary valence lattices, primary valence networks and primary valence chains—is afforded by the silicates whose structure elucidation is due in the first place to the experiments of W. L. Bragg and his co-workers over many years. For these very compounds the old method borrowed from organic chemistry of description by the aid of constitutional formulas was shown to be inappropriate. 

All our knowledge of simple chemical reactions appears practically to exclude the idea that the n single molecules on the left hand side of equation (116) associate instantaneously and that the primary valence chain is formed suddenly by a single complicated collision of many particles. 

We all know that the hot phase of his fight for macromolecules started with three papers in 1920, 1922 and 1924 liber Polymerisation [9], liber die Hydrierung des Kautschuks [10] (with the first definition of macromolecules as primary valence chain systems), and liber die Konstitution des Kautschuks ... 

I do, however, consider it sensible to introduce the word primary valence chain , because it refers to structures that are not completely identical to what has been called a molecule up to now. 1 always associate the word molecule with the concept of a large number of completely identical structures, whereas the term primary valence chain is specifically supposed to include the fact that the same substance contains structures that are very similar to each other, cannot be separated from each other by chemical methods but differ from one another a little in their size, so that while it is not possible to indicate a precise molecular weight, an average primary valence chain length can be quoted. If this fact is specifically added to your macromolecule, then the two terms are, as far as I can see, identical and it is a question of convenience whether one says primary valence chains or macromolecules of fluctuating size . 

Another center of textile fibre science was Birmingham and Sir Walter Norman Haworth (1883-1950, FRS, Nobel 1937) presented a very detailed report on the primary valence chains of several polysaccharides. Cellulose was shown by direct chemical analysis to contain from 100 to 200 subunits in a linear chain. Starch was analyzed in a similar fashion and found to be from 24 to 30 glucopyranose units. Glycogen is even shorter(12 units). The fundamentally different substance, inulin, is a fructofuranose of approximately 30 units. Macromolecules are envisioned in a fully modern sense in this paper. The three dimensional aspects were also addressed, since 1,4-glucose linkages produced different chains than 1,2-furanose linkages. 

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