Polymer Characterization: Polymer Molecular Weight Determination

Polymers are large molecules consisting of a large number of small component molecules chemically linked together. They are made from constituent monomers through polymerization process. Polymers are unique materials in that they consist of a statistical distribution of chains of varying lengths, and each chain consists of monomer residues which affect its properties hence they require several parameters which need to be specified. Polymerization reactions produce a distribution of molecular weights and shapes. Polymer molecular weight could be expressed as number average molecular weight, weight average molecular weight, and polydispersity. Some of the most common methods for determining these parameters are colligative property measurements, light scattering techniques, viscometry, and size exclusion chromatography. Gel permeation chromatography is used to determine the number average molecular weight, weight average molecular weight, and polydispersity.