Copolymer Fingerprints of Polystyrene-<i>block</i>-polyisoprene by\nMALDI-ToF-MS

Abstract

MALDI-ToF-MS mass spectra of copolymers contain a lot of information on both chain length\ndistribution (CLD) and chemical composition distribution (CCD). In this paper an approach for extracting\ndetailed information from a MALDI-ToF-MS mass spectrum is presented that enables the study of\nmicrostructure for copolymers. More specifically, this paper is dealing with a polystyrene-<i>block</i>-polyisoprene copolymer, in which the growth of the second block is followed with MALDI-ToF-MS as a\nfunction of conversion. The technique is compared to ¹H NMR for the evaluation of average chemical\ncompositions, revealing that ionization efficiencies do not influence the obtained mass spectra. It is shown\nthat MALDI-ToF-MS can extract detailed information on the chain length distributions (CLDs) for both\npolystyrene and polyisoprene blocks. Using random coupling statistics, it is shown that the proposed\nanalysis yields results with a high accuracy.