Investigating the effect of different catalytic systems on chain structure and end groups of CO2-based polycarbonates by MALDI-TOF mass spectrometry

The alternating copolymerization of CO2 and CHO with salen-type chromium complexes salenCrX, where X is chloride (1) or azide (2) with different cocatalysts under the same experimental conditions, has been described. The cocatalysts include TPPCl, DMAP, UHFFA, PPNY and PPZY salts, where Y is chloride or azide. A detailed end-group analysis via MALDI-TOF was performed and the complex patterns of MALDI-TOF spectra of the copolymers were rationalized for comparison with results obtained by 1H NMR spectroscopy, as well as by the catalytic behavior and copolymer characteristics. It appears that the entire structure of the cocatalyst, and not only the anion, should be considered in designing the structure of polycarbonates.