Transformation Of Carbon Monoxide To Aliphatic Polyester Via A Lactone Intermediate

With the development of the national economy and the improvement of people’s living standard,synthetic polymer materials have replaced traditional metals,glasses,ceramics,woods and other materials in many fields,with widely used.However,the ensuing energy and environmental problems have been caused,especially for the white pollution.People gradually realize the importance of protecting the environment,so the development of biodegradable materials is extremely vital.As we all know,the aliphatic polyester possessed good biodegradability.Besides,the carbon monoxide（CO）is the beginning in C1 chemistry,alkylene oxide is also a cheap bulk chemical.Once can we achieve the direct carbonylation polymerization of carbon monoxide and alkylene oxide,great scientific research and industrial production value can be realized,so it is practically significant for reducing the dependence on petroleum-based polymer materials nowadays,as well as solving the polymer waste pollution problems.Firstly,wesynthesizedabinuclear[（salph）M（THF）₂][Co（CO）₄]（salph=（3,5-^tBu-1-OH-C₆H₂）CH=N-C₆H₄-N=CH-（3,5-^tBu-1-OH-C₆H₂）,M=Al,Cr,Co）complexes,the reac-tion of direct carbonylation polymerization of alkylene oxide and carbon monoxide for preparing aliphatic polyester was studied by examining the acidity of the center metal,catalyst loading,type of additives,reaction conditions,etc..Then we tried a two-step method to achieve the conversion of alkylene oxide and carbon monoxide to aliphatic polyester,which is,alkylene oxide was firstly carbonylated to lactone intermediate,and the ring-opening polymerization of lactone was then occurred to form polyester.The carbonylation reaction of epoxycyclopentane（CPO）and carbon monoxide was studied with single metal SalenCr（III）-Cl as the catalyst and dicobalt octacarbonyl as the additive,and theβ-lactone intermediate（CPL）was selectively obtained here.Later,using metal complexes and organic bases as catalysts,the ring-opening polymerization reaction of lactone CPL for preparing aliphatic polyesters was studied.It was found that the catalyst structure had a significant effect on polymerization activity,polyester molecular weight,molecular weight distribution,topological structure and so on.The end groups of the polymer and the cis/trans structure of degradation products were studied by MALDI-TOF,nuclear magnetic,gas chromatography,etc.,The possible mechanism of ring-opening polymerization was also proposed.Then,a rare earth metal catalyst tetradentate aminobisphenol alkyl yttrium complex was used to catalyze the ring-opening polymerization of the lactone.The catalyst system can achieve efficient polymerization in the ratio of monomer/catalyst of 5000/1,controllable molecular weight and narrow molecular weight distribution were also obtained.Furthermore,a systematical study on the regioselectivity of the ring opening positions during the ring opening polymerization process of CPL is investigated.