ABSTRACT
Copolymers are characterized by a chemical composition distribution (CCD) that is represented by the mass fraction of molecules of a given copolymer composition vs. the copolymer composition. This characteristic considerably complicates the determination of the molecular weight distribution (MWD) of a copolymer by size exclusion chromatography (SEC) (1-7). However, there are two situations where copolymers can be almost treated as homopolymers from the point of view of the MWD estimation: (1) when the CCD is very narrow, or (2) (more generally) when the average composition does not change with hydrodynamic volume. Copolymers with narrow CCDs are in general desirable from the point of view of their end properties, and a control of the chemical composition along the copolymerization may be necessary for producing narrow CCDs. More normally, however, the average composition changes along the polymerization, and also zv140 possibly with hydrodynamic volume (8). In this work, we shall limit our discussion to copolymers containing only two repeating units types.
