Determination of zinc glutarate complexes synthesis factors affecting production of propylene carbonate from carbon dioxide and propylene oxide

- Zinc glutarate (ZnGA) catalyst copolymerize carbon dioxide and propylene oxide.
- High crystallinity ZnGA produce higher yield and selectivity of polypropylene carbonate (PPC).
- Producing PPC with high molecular weight (97,100 Da) and narrow polydispersity index (1.28).

The purpose of this research was to investigate the effects of catalyst preparation temperature and time, and catalyst size in relation to the performance of the zinc glutarate (ZnGA) catalyst and the polypropylene carbonate (PPC) produced. Various ZnGA catalysts were synthesized at several combinations of temperature (40 °C, 50 °C, 60 °C and 70 °C) and time (3 h, 6 h and 9 h). The ZnGA were then used to copolymerize propylene oxide and carbon dioxide to produce PPC. It is found that the catalyst preparation temperature plays a dominant role in affecting the catalytic activity of the ZnGA. The ZnGA catalyst produced at higher temperature were found to possess higher crystallinity and capable to produce higher yield and selectivity PPC. However, the incorporation of glutaric acid into the catalyst is vital as well. Although some of the ZnGA exhibit high crystallinity, their low intensity of characteristic peaks of zinc-carboxylate bond (COO-) may causes low yield of PPC with byproducts. This is especially found on the catalysts synthesized at lower temperature (40 °C). Among the all the combinations of temperature and time, the ZnGA prepared using 9 h at 70 °C possess the highest crystallinity (42.52%) and has the best incorporation of GA (1.24 a.u.). It is capable of producing PPC with high molecular weight (97,100 Da) and narrow PDI (1.28), high crystallinity (23.44%), high and narrow Tm at 244 °C with excellent mechanical properties (tensile strength of 8.48 MPa, tensile elongation >400%, and Young's modulus of 748.7 MPa).

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