Characterization of chemical heterogeneity of graft copolymer by conventional SEC

Poly(methyl methacrylate) grafted with poly(dimethylsiloxane) was investiga ted by size exclusion chromatography coupled with refractometric and low-an gle laser light scattering detectors. Using successively toluene and tetrah ydrofuran as eluents, a variation in chemical composition and molecular wei ght of individual copolymer blocks as a function of hydrodynamic volume wer e measured. Chemical composition distribution and heterogeneity parameters of the copolymerization product were approximated and compared with the res ults obtained by supercritical fluid extraction fractionation and by fracti onation in demixing solvents.