Online size exclusion chromatography Fourier transform infrared spectroscopy (FTIR): Investigation of preferential solvation effects

Light scattering investigations of alternating copolymers of maleic anhydride and styrene or methyl maleimide and styrene were carried out in tetrahydrofuran (THF) containing a small amount of water. A systematic decrease of the apparent molecular weight (M-w(app)) calculated from light scattering data is observed when the water content in THF is increased. It is assumed that strong interactions among polymer molecules exist in THF and that they are disrupted by addition of water. Simultaneously preferential solvation of the polar sequences of the copolymer molecule should be considered. This special form of solvation is characterized by both size exclusion chromatography/FTIR coupled technique (SEC/FTIR) and stationary FTIR experiments using low-molecular-weight model compounds with similar chemical structure as, for example, N-methyl succinimide.