Studies On The Novel Catalysts Prepared For The Copolymerization Of CO₂and Epoxides

Carbon dioxide （CO₂） is the main factor to cause green house effect; but today itis also an important carbon resource. The efficient use of CO₂has become the focus inthe world. One of the effective ways to fix the carbon-dioxide is to prepare aliphaticpolycarbonate by copolymerization of CO₂and epoxy compounds. Poly（propylenecarbonate）（PPC） derived from the copolymerizaion of CO₂and propylene oxide, is analiphatic polycarbonate with reasonably good mechanical and biodegradableproperties, which can be used as degradable plastic for controlling the challengingenvironment problem of white pollution.Zinc glutarate （ZnGA） has been considered one of the most prospective catalystsfor industrial applications in the copolymerization of CO₂and epoxides. However, itis a challenging problem that the yield rate of PPC in the copolymerization of CO₂and propylene oxide catalyzed by ZnGA is low. Therefore, modified catalysts weredesigned to improve the catalytic activity of ZnGA in this study. The catalyticactivities of modified ZnGA in the copolymerization of CO₂and propylene oxidewere investigated in detail.Part Ⅰ:Modified ZnGA（PTSA-ZnGA） catalysts were prepared from p-toluene sulfonicacid （PTSA）, zinc oxide and glutaratic acid and they were used in thecopolymerization of CO₂and propylene oxide. The results showed that the catalyticactivities of PTSA-ZnGA in the copolymerization of CO₂and propylene oxide werehigher than that of ZnGA. The yield of PPC obtained from the catalyst ofPTSA-ZnGA was2.8times more than that catalyzed by ZnGA. Molecular weight ofPPC improved from5.12x10⁴to6.65x10⁴with a smaller PDI. The structure ofPTSA-ZnGA was characterized by fourier transform infrared spectroscopy （FT-IR）,wide angle X-ray diffraction （WXRD） and BET surface area（BET）. From the aboveresults, we can conclude that the catalytic activity of PTSA-ZnGA in thecopolymerization of CO₂and propylene oxide depends on the crystallinity and surfacearea of catalyst. Part Ⅱ:Modified ZnGA（PDMA-ZnGA） catalysts were prepared from pyromelliticdianhydride （PMDA）, zinc oxide and glutaratic acid. The catalytic activity ofPDMA-ZnGA in the copolymerization of CO₂and PO were investigated. The resultsindicated that catalytic activity of ZnGA was improved significantly by themodification of PMDA. The yield of PPC catalyzed by PDMA-ZnGA was higher thanthat catalyzed by ZnGA. The structure of PDMA-ZnGA was characterized by FT-IR,WXRD and BET, the results indicated that crystallinity and surface area of catalyst isthe key to improve the catalytic activity of PDMA-ZnGA.Part Ⅲ:Modified ZnGA （PTSA-PDMA-ZnGA） catalysts prepared from mixedacid（PTSA and PMDA）, zinc oxide and glutaratic acid were used in thecopolymerization between carbon dioxide and propylene oxide. PTSA-PDMA-ZnGAand PPC were characterized by FT-IR，WXRD,1H NMR and GPC. We found that thecatalytic activity of ZnGA in the copolymerization of CO₂and propylene oxide waseffective improved, it was due to the high crystallinity of PTSA-PDMA-ZnGA.