Applications of Laser Light Scattering in Polymer Dilute Solution Characterization

Dynamic light scattering or photon correlation spectroscopy, PCS can be used to determine the frequency distribution of the light scattered from polymer solutions. This distribution contains information about the dynamics of the system. Depending on the wavelength of radiation and the size of the polymer molecule, the translations and rotations of the entire molecule, or the motions of the monomers can be studied. This information, combined with static light scattering the traditional Zimm Plot analysis, can yield a molecular weight distribution MWD, z-average radius of gyration R sub g, hydrodynamic radius R sub h, translational diffusion coefficient D sub t, and in some cases a rotational diffusion coefficient D sub r. Dynamic light scattering DLS has been used extensively in the dilute solution regime to determine the type of information listed above, and the theories associated with the various phenomena are well defined. DLS can also be applied to the analyses of semi-dilute solutions and to study the dynamics of entangled systems e.g., polymer melts or diffusion of polymer chains in a matrix., although the interpretation of this type of DLS is still speculative. This report will focus on the use of DLS to determine translational diffusion coefficients, and the combination of static and dynamic Light scattering to determine molecular weight distributions.... Light scattering, Molecular weight, Solutions, Polystyrene.