As we contemplate the centennial of macromolecular chemistry, we may be reasonably certain that Hermann Staudinger never said “Polymer scientia est omnis divisa in partes tres,” but if he had, he would have been right! The first part of polymer chemistry is synthesis: what molecular structures can we make, how easily, and how reproducibly? The third part comprises material properties: what is this polymer good for, how can we make it better, and how can we combine multiple desirable properties in one material? The intermediate domain, and the essential component in order to close the structure-property loop, is polymer characterization: what did we make, exactly?
There is no doubt that polymer characterization is, in general, a formidable experimental challenge. At the root of the problem is the unavoidable fact that all synthetic polymers are het- erogeneous in their molecular structure. A simple calculation reveals that even a tank car full of homopolymer will not contain two molecules that are precisely identical. Not only is there a distribution of molar mass, but there is also heterogeneity in multiple variables, including, for example, regioisomerism, stereochemistry, long- and short-chain branching, and copoly- mer sequence and composition. Ideally, we would like to characterize all of these distributions, at least to the level of a mean value and a variance. This goal is currently beyond the capabilities of most laboratories, although experimental science continues to advance significantly.