Synthesis of alternating and random copolymers of ethylene with maleic anhydride

The radical copolymerization of ethylene with maleic anhydride has been investigated over a wide range of pressure (10–150 MPa), temperature (70–235°) and comonomer concentrations (0·1–60 mole %) in the presence of various solvents and initiators. Only alternating copolymers are formed at 150°, irrespective of the initial ratio of monomers and pressure, and irrespective of the medium. Above 200° random copolymers containing 0·4–13 mole% anhydride units are formed. The relative reactivity of ethylene in the random copolymerization was equal to 0·045±0·019. The dependence of the rate of formation of alternating copolymers on the maleic anhydride concentration was expressed by an extremal type of relationship, a maximum being obtained at an equimolar ratio of monomers. It was found that the rate and degree of copolymerization depend on pressure and temperature, on the polarity of the solvent, and on the initiator concentration.