Strong Donor Solvents Research Articles

Solvent effects on the alternating copolymerization systems. Evaluation on equilibrium constants by NMR spectroscopy

AbstractThe contributions of the charge‐transfer complexes to the alternating copolymerizations (e.g., the styrene/maleic anhydride system) were studied. From the facts that the complex concentrations changed in various solvents and the rates of copolymerization depended on the solvent species, the behavior of the alternating copolymerization was considered to be controlled by the quantities of the reactive monomer complexes.In relatively strong donor solvents such as acetone and tetrahydrofuran, the concentrations of the monomer complexes were low because acceptor monomers also form complexes with the solvents. Therefore, the contributions of the monomer complexes to the copolymerization were neglectable. On the other hand, in benzene and carbon tetrachloride, which interact with acceptor monomers relatively weakly, the concentrations of the monomer complexes were relatively high. Then the copolymerizations were mainly controlled by the reactive monomer complexes.After all, it was suggested that the uncomplexed monomers as well as the complexed monomers should be taken into account on discussing the mechanisms of the alternating copolymerization between donor and acceptor monomers. In addition, the equilibrium constants or the complex concentrations could be determined in n‐hexane by the use of NMR spectra.