Chromatographic study of the conformational behavior of graft copolymers with a broad distribution of grafting densities in dilute solutions in selective solvents for grafts

ABSTRACT

A graft copolymer of poly(4-methylstyrene-graft-2-vinylpyridine) was prepared by the living “grafting onto” method. Its molecular weight and composition was analyzed by size-exclusion chromatography, liquid chromatography under limiting conditions of desorption, ¹H NMR, and light scattering. The results indicated a non-negligibly broad distribution of grafting density. Its conformational behavior was studied by reversed phase liquid chromatography with gradient elution. Targeted studies provided two discrete base-line separated fractions. Their compositions were estimated by pyrolysis gas chromatography. The results suggest that distinct chain conformations (differing in grafting density and interacting differently with stationary phase) exist in studied solutions and can be separated by well-tuned chromatographic techniques. Experimental data were analyzed and interpreted on the basis of theoretical and computer studies of the conformational behavior of graft copolymers in selective solvents.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chain conformations
• interaction chromatography
• grafting density
• poly(4-methylstyrene)-graft-poly(2-vinylpyridine)
• selective solvent
• size exclusion chromatography