COMPOSITION AND SEQUENCE OF COPOLYMERS FROM MASS SPECTROMETRIC DATA, ALONG WITH THE IDENTIFICATION OF DIFFERENT TYPES OF CHAIN-ENDS

The task of recording the MALDI mass spectrum of a soluble (or partially insoluble) copolymer is nowadays routine, both for condensation copolymers and for addition copolymers. The peak-assignment procedure is identical for homopolymers and copolymers (although the latter mass spectra are much richer in peaks) and it is seldom (virtually never) done without some a-priori knowledge of the synthetic procedure, along with possible end-groups. Thereafter, a theoretical mass spectrum is generated and compared with the experimental one. The minimization program yields the covariance matrix. The diagonal elements of the cited matrix are exactly coincident with the error in the composition and sequence. We studied mass spectra of a series of terpolymers containing units of maleic anhydride (MAH), maleic acid (MA) and styrene (ST), copolymers containing units of glycine (GL) and lactic acid (LA), copolymers containing units of ethyleneoxide (EO) and propylene oxide (PO), copolymers containing units of methyl methacrylate (MMA) and butyl-acrylate (PBA) and we performed a systematic study on an large group of condensation copolymers and terpolymers obtained reacting a diol (butane-diol) with various aliphatic and aromatic di-acids.