摘要

Alternative copolymers of maleic anhydride (MA) and ethyl vinyl ether (EVE) [P(MA-alt-EVE)] were prepared in supercritical carbon dioxide (scCO(2)). The chemical structure of the obtained P(MA-alt-EVE)s was characterized by FT-IR and C-13 NMR spectroscopy and showed that the copolymers possess strictly alternating structure. The influences of MA/EVE feed ratio, reaction time, and solvent as well as the initial initiator concentration on the copolymerization were also studied. It was indicated that the increase rate of reaction pressure could be related with good accuracy to monomer conversion, providing a simple and efficient method for monitoring the reaction processes. Gel Permeation Chromatography examination of the alternative copolymers revealed that the molecular weights of P(MA-alt-EVE) synthesized in scCO(2) at different pressures were all higher than those prepared in organic solvents. Thermal properties were investigated by TGA and showed P(MA-alt-EVE) has good thermal stability (T-d=251 degrees C). Comparison studies on the P(MA-alt-EVE) in scCO(2) and that prepared in organic solvent exhibit scCO(2) solvent and it plays an important role in the copolymerization of MA and EVE.

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