The History of Covalent Structures

All flexible macromolecules must contain at least a sequence of linear, covalently bonded atoms. The understanding of the cylindrically symmetric, directed, covalent bonds (sigma bonds) was thus the first step towards polymer science. This step was already taken in 1858 by Kekuld as shown in Fig. 1.8. The detailed structures of large aggregates of atoms (macromolecules) could next be analyzed in detail after X-ray diffraction was fully understood. Major steps in the development of X-ray analysis of macromolecules are listed in the figure. First, rigid macromolecules such as metals, salts, minerals, and ceramics were analyzed. This was followed by many polymer crystal structures and even globular proteins. 

The general reference to the book by Flory contains a brief, expert summary of the history of knowledge about polymers and is a treatise on polymer physical chemistry. (See also the list of general references for this section). The delay in development of polymer science due to the misunderstanding of colloid science (microphases) is discussed next. 

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