Relation between the alternating monomer unit sequence and the cis and trans linkage configurations at the cyclic maleic anhydride units in the copolymers of styrene and maleic anhydride prepared in carbon tetrachloride

Abstract

AbstractThe monomer unit triad sequence distribution and the cis/trans linkage configurations at the cyclic maleic anhydride (MA) units in the copolymers of styrene (ST) and MA prepared in CCl4 with AIBN at 50°C were quantitatively determined by 13C DEPT NMR spectroscopy. So much as 61 % of the linkages at the MA units were found to be in cis configuration, which was considered to be formed by a participation of the 1:1 electron donor‐acceptor complex formed between ST and MA in the propagation step. The mole fraction of the cis configuration was found to be proportional to the mole fraction of alternating triad sequences when the monomer unit sequences approach to be completely alternating. This supported the proposal that, in alternating and semi‐alternating copolymerizations, the alternating sequences were formed mainly by the addition of the complex. The equilibrium constant of the complexation in CCl4 at 23°C was determined to be 0,21 L/mol.