Flow rate and concentration-dependent effects of molecular dynamics on elution behaviors of flexible polymers in gel permeation chromatography: A multi-angle laser light scattering study

摘要

Gel permeation chromatography (GPC) coupled with multi-angle laser light scattering (MALLS) provides a tool to simultaneously measure the elution behavior and molecular shape of flexible polymers in their dependence on column flow rate and solute concentration. As flow rate was increased, the radius of gyration (R-g) of flexible polymers first decreased a little and then increased gradually. In all cases, the values of R-g, the hydrodynamic radius (R-h), and rho (R-g/R-h) decreased as the concentration increased. As a result, flow-induced molecular stretch and concentration-induced molecular shrinking for flexible polymers in the gel pores were deduced from the size-related elution behaviors and tested by light scattering. In addition, the flow rate and concentration-dependent effect of elution behavior parameters such as the elution volume (V-e), the weight-averaged molecular weight (M-w), and polydispersity index (PI) were interpreted in terms of molecular deformation and orientations of flexible polymers.