Analysis of poly(styrene-co-methyl acrylate) and poly(styrene-co-butyl acrylate) by high-performance liquid chromatography

Poly(styrene—co-methyl acrylate) and poly(styrene—co-butyl acrylate) were separated according to their chemical composition by gradient elution. The chromatographic separation on silica was optimized for a gradient ranging from n-heptane as a non-solvent to dichloromethane containing a small amount of methanol as a strong solvent. The influence of different stationary phases, the chemical composition and molecular mass on the separation of the copolymers was investigated. From the results of different chromatographic and turbidimetric experiments it is concluded that the copolymer separation is controlled by both precipitation and adsorption mechanisms. The contribution of adsorption processes to the separation is only advantageous when normal-phase gradients are applied