DIELS-ALDER REACTION OF FURFURYL GLYCIDYL ETHER/CARBON DIOXIDE COPOLYMER

Diels-Alder (DA) reaction between N-phenyl maleimide and the pendant furan ring of the CO2 and furfuryl glycidyl ether copolymer (PFGEC) was employed for stabilization of PFGEC by reducing the amount of furan ring and introducing bulky groups into PFGEC. The stability of the product was enhanced by increasing the cyclization degree, the PFGEC with cyclization degree above 70% was air stable. Optimal reaction conditions were obtained, taking the N-phenyl maleimide as an example, cyclization degree as high as 84. 1% was realized when the DA reaction was carried out in dimethyl carbonate at 60 degrees C for 24 h with molar ratio of N-phenyl maleimide to furan ring of 3 : 1. The DA reaction was endothermal reaction, raising reaction temperature generally can raise cyclization degree, however, DA reaction was also a reversible process, when the temperature was high enough, reverse reaction (r-DA) existed, e.g., when the DA product of PFGEC with cyclization degree of 72. 1% was heated in dimethyl sulfoixde solution at 100 degrees C for 10 min, the cyclization degree decreased to 40. 4%, indicating that the r-DA reaction proceeded quite fast at temperatures above 100 degrees C.