ABSTRACT
As compared with small molecules, which consist of single molecular weight species, synthetic polymers are comprised of hundreds to thousands of chains of differing molecular weights, each with a finite concentration. The characteristics of the molecular weight distribution of a polymer are governed by the polymerization mechanism, monomer reactivity ratios, monomer feed rates, initiator type, presence of chain-transfer agents, and polymerization and processing conditions. In addition to synthetic polymers, many naturally occurring polymers, such as polysaccharides, cellulosics, natural rubber, and some proteins, also have defined molecular weight distributions. These materials are considered polydisperse. Nucleic acids and most types of proteins, however, consist of a single, well-defined molecular weight structure, and they are defined as monodisperse.
