Study On The Copolymerization Of CO_2 And Epoxy Compounds Catalyzed By Polyaniline - Salen Complexes

Nowadays, much attention has been paid to the copolymerization of carbon dioxide and epoxide to produce polymeric materials, the significant amount of research has been directed towards the development of catalysts with improved activity and selectivity. Although, the homogeneous catalytic system of SalenMX possesses some advantages such as easy preparation, less sensitive to water and air, high catalytic activities and good selectivities, the poisonous metal Cr, Co can not be recycle use, it has retricted their industrial use. Supporting catalyst strategy is a good choice to achieve catalyst recycles use. In this paper,the copolymerization of carbon dioxide with cyclohexene oxide (CHO) was carried out using polyaniline (PANI) supported SalenCrⅢCl catalyst. The effect of coplymerization conditions and thermal degradation performance were studied. The main contents are as follows:1. Polyaniline nanofibers were synthesized through interfacial polymerization, where PANI nanofibers act as supporter to immobilize SalenCrⅢCl. Ultraviolet-visble (UV-vis) spectra, fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscope (XPS) are used to characterize SalenCrⅢCl-PAN supported catalyst.2. The reaction conditions of the mass of catalyst, cocatalysts, the mole ratio of catalyst and cocatalyst, the reaction temperature, the pressure and the reaction time for the copolymerization of CO2 with CHO have been studied, the optimum condations are:CHO(5mL), m(SalenCrⅢ Cl-PANI)=0.42 g, m (SalenCrⅢ Cl-PANI):[PPN]Cl=1000:1, T= 80℃,PCO2=5.0 MPa, t=10h. catalytic activity=12.91 gPolym/gSupp,conversion rate of monomer=99.03%, s electivity>99%, carbonate>96%, Mn=12.21×103g/mol, PDI=1.16.3. The copolymerization products were characterized by 1H NMR and 13C NMR spectroscopy, thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results of the products for different catalysts have shown that the structures are same, the molecular weight, the temperature of the maximum degradation(Tp=296℃) and the glass temperature(Tg=116.5) of the products prepared by supported catalyst are higer which exhibited better thermal stability.4. Polycarbonates were prepared by two catalysts(SalenCrⅢ Cl and SalenCrⅢ Cl-PANI), their thermal degradation kinetics were studied in different heating rates.The degradation activation energy (Ek) values were estimated by Flynn-Wall-Ozawa (FWO)method, Kissinger method, and Coats-Redfern method, respectively. The thermal degradation reaction mechanism is Phase boundary controlled reaction (one-dimensional movement)...