Abstract
Ring-opening copolymerizations of succinic anhydride (SAn, 1) or maleic anhydride (MAn, 2) with propylene oxide (PO) were carried out by using magnesium diethoxide (Mg(OEt)2) as a catalyst. The unsaturated polyester (P2a) was found to have only Z-configuration around a C=C double bond from its 1H and 13C NMR spectra. Isomerization reaction of P2a from Z- to E-configuration was performed in 1,2-dichloroethane with a catalytic amount of morpholine. Thus unsaturated polyesters, P2b-e, having the same molecular weight but the different ratio of Z-/E-configuration could be optionally prepared from one original polymer P2a by controlling isomerization reaction time. Biodegradability of these polyester samples was evaluated from their biochemical oxygen demand (BOD) values in the presence of an activated sludge. Polyester P2a was hardly degraded during measurement. However, polyesters P2b-e, partially containing E-configuration of the C=C double bond, degraded considerably faster than P2a itself. The biodegradability of saturated polyester P1 was also examined to compare with the P2-series.
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