Study On The Copolymerization Of SO₂ And Epoxy Compounds Catalyzed By Salen-type Catalysts

The utilization of Sulfur dioxide?SO₂?is confined to prepare sulfuric acid which is technology of excess capacity and high-energy consumption,and it also develops slowly compared with SO₂ capture.Researchers found thatSO₂canbecopolymerizedwithepoxidetoprepare sulfur-contain-polymer,which named poly sulfite,in last century,however,it accompanied by negative factors such as rigor of reaction temperature and low conversion.Based on the mechanism of copolymerization of carbon dioxide?CO₂?and epoxide which catalyzed by Salen-type complex,3Salen-type catalysts were prepared to overcome the negative factors of copolymerization of SO₂ and epoxide,as well as provide new ways for the resource utilization of SO₂.We have done the following works:SalenH ligand was prepared by?R,R?-1,2-diaminocyclohexane and3,5-di-tert-butyl-2-hydroxybenzaldehyde through Schiff reaction,thereafter,SalenH ligand chelated chromium chloride to form homogeneous SalenCr^IIICl catalyst.SalenCr^IIICl catalyst was used for copolymerization of sulfur dioxide with epoxide.We found SalenCr^IIICl catalyst has excellent catalytic activity in copolymerization by investigating reaction time,reaction temperature,reaction pressure,and catalyst amount etc.,and obtained the optimal conditions.We investigated the products by fourier transform infrared spectroscopy?FITR?,nuclear magnetic resonance?NMR?,and thermogravimetry?TG?.Cellulose was modified by thionyl chloride and ethylenedimine to preparedaminodeoxycellulose.Thereafter,3,5-di-tert-butyl-2-hydroxybenzaldehyde and aminodeoxycellulose have been used to prepare cellulosic SalenH ligand by Schiff reaction.Finally,cellulosic SalenH ligand chelated chromium chloride to form heterogeneous cellulosic SalenCr^IIICl catalyst.Cellulosic SalenCr^IIICl catalyst was used to copolymerization of sulfur dioxide with epoxide.We found cellulosic SalenCr^IIICl catalyst has excellent catalytic activity in copolymerization of sulfur dioxide with epoxide by investigating reaction time,reaction temperature,reaction pressure,and catalyst amout etc.,and obtained the optimal conditions.We investigated the products by FITR,NMR,and TG.HomogeneousSalenCr^IIIClcatalystwasmodifiedtoform SalenCr^IIIClO₄,thereafter,aminodeoxycellulose support ed SalenCr^IIIClO₄catalyst was synthesized by cellulose supported SalenCr^IIIClO₄.We found cellulose supported SalenCr^IIIClO₄ catalyst has excellent catalytic activity in copolymerization by investigating reaction time,reaction temperature,reaction pressure,and catalyst amout etc.,and obtained the optimal conditions.We investigated the products by FITR,NMR,and TG.The mechanism of copolymerization of sulfur dioxide with epoxide was studied through contrast and blank experiment,representation of FTIR,¹H NMR and ¹³C NMR.In copolymerization of sulfur dioxide with epoxide,we found sulfur dioxide is not only as reactant,but also as nucleophile to participate in reaction.Thermal degradation kinetics of poly?cyclohexene sulfite?and poly?cyclohexene carbonate sulfite?was studied through thermogravimetry.Based on the data of thermogravimetry curves of different heating rates,thermal degradation kinetics parameters were analyzed by methods of Flynn-Wall-Ozawa,Kissinger and Coats-Redfern.