MALDI for the estimation of viscosity parameters. A modified method which applies also to polycondensates

Recently, a method based on MALDI was described for the estn. of the parameters which characterize the viscosity of a polymer, namely the Mark-Houwink-Sakurada (MHS) parameters. The method makes use of samples with a narrow molar mass distribution and therefore, for polycondensates, it may become unpractical. A modification is proposed here, based on the universal calibration concept and on the coupling of size exclusion chromatog. and MALDI. The new method is applied to two copolymers with units of styrene and maleic-anhydride and to a series of polymers and copolymers obtained by condensation. The MHS parameters are measured and they are compared with the values predicted by the method of adding the contributions coming from each functional group present in the chain, which is able to predict MHS parameters from first principles.