Multistage mass spectrometry studies on the chemical structure
of aliphatic polyester macromolecules
Polimery 2001, No 7-8, 501
SummaryMultistage mass spectrometry used in combination with electrospray ionization method (ESI-MS) was used to investigate the chemical structure of synthetic models of aliphatic polyesters, viz., poly[(R, S)-beta-butyrolactone] and poly(alpha-methyl-beta-pentyl-beta-propiolactone), prepared by anionic polymerization of suitable lactones (Scheme A) and natural aliphatic copolymers (PHA). The study comprised: (i) analysis of end groups and verification of their chemical homogeneity (Figs. l, 2); (ii) determination of M and MWD (Fig. 3); (iii) determination of sequence distribution in, and chemical structure of, selected aliphatic copolymers (Figs. 4-6). The ESI-MS technique affords the information essential for establishing the mechanisms of polymerization and the yield of chain termination reactions. For PHA, this technique enabled the distribution of monomer sequence to be established over a broader range of M as compared with that reported for PHA studied by "soft" ionization MS techniques other than ESI, as well as by fragmentation analysis of chemical structure of individual copolyester molecular ions. It enabled - for the first time - the statistical distribution of the mers incorporated into the chains of selected PHA to be verified.