Polymer characterization by temperature gradient interaction chromatography

Abstract

Thermodynamic principles and some applications of the temperature gradient interaction chromatography (TGIC) recently developed for the characterization of synthetic polymers are described. TGIC is a form of high performance liquid chromatography (HPLC) that varies column temperature in a programmed manner to control the retention of polymeric species during isocratic elution. The retention of polymers strongly depends on their molecular weights, and the polymers are well separated by TGIC in terms of their molecular weights. TGIC is superior to size exclusion chromatography (SEC) in resolution and sample loading capacity, and has higher sensitivity to molecular weight in the analysis of nonlinear polymers. TGIC has an advantage over solvent gradient HPLC because it permits the use of refractive index sensitive detection method such as differential refractometry and light scattering due to the isocratic elution. In addition, temperature provides finer and more reproducible retention control than the solvent composition, which is important in determining the molecular weight distribution by secondary calibration methods. With TGIC analysis, we found that the molecular weight distribution of anionically polymerized polymers is much narrower than has been generally accepted from SEC analysis. We also found the TGIC separation conditions for polystyrene, polyisoprene, poly(methyl methacrylate), poly(vinyl chloride), and poly(vinyl acetate) over wide molecular weight range. Because of its sensitivity to the molecular weight alone, TGIC was successfully applied to the characterization of star shaped polystyrene, and the detailed linking kinetics between living polystyrene anions and a chlorosilane linking agent was investigated.