Ring opening copolymerization of succinic anhydride-ethylene oxide by Al (III) organometallic catalysts

Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO) was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at 62+/-2 degrees C. The results showed that in-situ AlR3-H2O (R=ethyl, iso-butyl) catalysts gave higher molecular weight ((M) over bar(w) similar to 10(4)), while AI(OR)(3) catalysts gave the higher alternating copolymer structure with slightly lower molecular weight. The in-situ AlR3-H2O systems have been evaluated in more detail for the reaction which showed the optimum H2O/Al molar ratio to be 0.5. The copolymers with different composition (F-SA/F-EO = 36/64 to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melting point (T-m), glass transition temperature (T-g) and enthalpy of fusion (Delta H-f) of these copolymers are depended on the copolymer composition and in the range of 87 similar to 102 degrees C, -12 similar to -18 degrees C, and 37 similar to 66 J/g, respectively. The second heating scan of DSC also indicated that the higher alternating copolymer was more easily recrystallised. The onset decomposition temperature was more than 300 degrees C under nitrogen and influenced by the copolymer composition.