A quantitative evaluation of the structure and properties of the methyl ester of divinyl ether - maleic anhydride 1:2 copolymer

The methyl ester of divinyl ether—maleic anhydride 1:2 copolymer (DME) has been used as a molecular probe to identify the structure of DIVEMA (divinyl ether—maleic anhydride 1:2 copolymer). Solution light scattering, gel permeation chromatography, and intrinsic viscosity measurements have shown that tetrahydrofuran at 30°C is a theta solvent for DME, and that DME has a random coil conformation with possible long chain branching at higher molecular weights. Determination of the characteristic ratio of DME required identification of its molecular structure. Molecular model studies revealed that the bulky methyl ester groups cause much more steric hindrance in the generally accepted tetrahydropyran structure of DME than in an alternative tetrahydrofuran structure. This observation, together with the polymer solution measurements, indicates the latter structure is more in accord with experimental data, suggesting that both DME and the parent DIVEMA contain tetrahydrofuran in their structures.