Methanolysis of poly(lactic acid) using acidic functionalized ionic liquids as catalysts

Abstract

ABSTRACT The methanolysis of poly(lactic acid) (PLA) was studied by using acidic ionic liquids (ILs) as catalyst in detail. The results showed that HSO 3 ‐functionalized ILs exhibited higher catalytic activity than non‐functionalized ILs and traditional acid catalyst such as H 2 SO 4 . The influences of experimental parameters, such as the amount of catalyst, reaction temperature, methanolysis time, and dosages of methanol on the conversion of PLA, yield of methyl lactate were investigated. Under the optimal conditions, using 1‐methyl‐3‐(3‐sulfopropyl)‐immidazolium hydrogen sulfate ([HSO 3 ‐pmim][HSO 4 ]) as catalyst, the IL could be reused up to six times without apparent decrease in the conversion of PLA and yield of methyl lactate. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA in [HSO 3 ‐pmim][HSO 4 ] was a first‐order kinetic reaction with activation energy of 47.01 kJ/mol and Arrhenius constant of 2.7 × 10 7 min −1 . © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40817.