Kinetics of poly(propylene fumarate) synthesis by step polymerization of diethyl fumarate and propylene glycol using zinc chloride as a catalyst

Diethyl fumarate and propylene glycol were reacted in the presence of a zinc chloride catalyst to synthesize poly(propylene fumarate) (PPF) over a period of 12 hours. The kinetics of the transesterification polymerization at 130degreesC, 150degreesC, and 200degreesC were determined by gel permeation chromatography (GPC) analysis. The initial rate of polymerization at each temperature was quantified by calculating the rate of change of the number average molecular weight (M-n). At 200degreesC, gelation of the PPF occurred after 4 h. GPC analysis of the reaction showed that PPF synthesized at 150degreesC had a higher final M-n of 4600 (+/-190) and a higher weight average molecular weight of 10 500 (+/-760) than at 130degreesC (n = 3). The chemical structure of the PPF was verified by NMR and FT-IR analysis. This study demonstrated that the maximum M-n of PPF by a transesterification reaction is limited due to gelation of PPF at high temperature.