Molar Mass and Microstructure Analysis of PI-b-PMMA Copolymers by SEC-NMR

The online coupling of size-exclusion chromatography and NMR is used to characterize block copolymers consisting of polyisoprene (PI) and poly(methyl methacrylate) (PMMA) regarding their distributions of molar mass (MMD) and chemical composition (CCD). Using the CCD, and are calculated on the basis of PI and PMMA homopolymer calibrations. The microstructure distribution of PMMA and the distribution of isomeric units of PI in dependence of molar mass is also demonstrated. Furthermore, a simulation analysis is presented for a bimodal eluting sample. It allows for full separation, quantification and molar mass determination of the coeluting co- and homopolymer fractions. The quantification of the fractions is verified by liquid chromatography at critical conditions.