Dynamic and Static Light Scattering study of Polymeric Microgels of Varying Crosslinking Concentration.

Structure and dynamics of polysaccharide polymeric microgels synthesized at various crosslinker concentrations were studied with Dynamic Light Scattering (DLS) and Static Light Scattering (SLS). DLS on these microgels revealed crosslinker-concentration-dependent dynamics below and above their volume phase transition. SLS with direct dn/dc measurements revealed the strong dependence of particle's structure and molecular weight on concentration of crosslinker. In particular, at higher crosslinker concentrations dn/dc showed a significant increase with increase of crosslinker concentration and under volume phase transition. Microgel scattering form factors were also found to depend on crosslinker concentration changing from shapes consistent with more spherical to less spherical shapes with the increase of the crosslinker amount. The overall light scattering analysis shows that the crosslinker concentration affects the apparent density and structure of microgels and could be related to non-uniform crosslinker distribution in microgels at higher crosslinker concentrations. Several potential explanations of the observed effects of crosslinker concentration are proposed.