Synthesis And Properties Of Nano Zinc Glutarate Catalyst

Poly(propylene carbonate)(PPC)is an environmentally friendly polymer,which is formed by the catalytic copolymerization of carbon dioxide(CO₂)and propylene oxide(PO).Due to its biodegradability and good gas barrier properties,PPC has potential applications in packaging and medical materials.Among them,zinc glutarate(ZnGA)catalyst is currently one of the catalysts suitable for the industrial production of PPC.The catalytically synthesized PPC has the advantages of large molecular weight,alternating structure of CO₂ and PO,and high carbonate linkage content,but its catalytic efficiency needs to be improved.As a heterogeneous catalyst,the specific surface area is an important factor affecting the catalytic efficiency of ZnGA.In this thesis,a simple method was used to synthesize a nano-sized ZnGA with high catalytic activity,which was used to catalyze the CO₂/PO copolymerization to synthesize PPC.The nano-sized ZnGA was characterized by XRD,SEM,specific surface area,and TGA.The structure and thermal properties of PPC were characterized by ¹H NMR,GPC,TGA,and DSC.In addition,the effects of the CO₂/PO copolymerization conditions on the catalytic efficiency of ZnGA as well as the structure and performance of PPC were investigated.The specific content is as follows:(1)Synthesis of nanosheet ZnGA catalyst(denoted as JM-ZnGA)by solution interface method.The N,N-dimethylformamide/acetonitrile mixture with different composition ratio was used as the upper,middle and lower layers with different density.The lower and upper layers dissolved glutaric acid and zinc acetate dihydrate,respectively.At a certain temperature,glutaric acid in the upper layer and zinc acetate in the lower layer diffused to the middle layer to form JM-ZnGA.The JM-ZnGA synthesized by the interface method was in the form of nanosheets.Compared with the traditional synthesis method of ZnGA,that is,zinc oxide and glutaric acid are strongly stirred in toluene solvent at 55?,the JM-ZnGA synthesized by the interface method had a smaller particle size,larger surface area and lower crystal integrity.The morphology of JM1-ZnGA synthesized at 40? was in the form of small flakes,while the JM2-ZnGA flakes synthesized at 80? becomed larger and wider.The JM3-ZnGA synthesized at 10 times glutaric acid concentration appeared to be aggregated with the morphology of the flower clusters.It was showed that the reaction temperature and the concentration of reactants had a certain influence on the morphology of the synthesized catalyst.The catalytic efficiency of the JM-ZnGA synthesized by this method was compared with that of the traditional ZnGA.The catalytic efficiency of JM1-ZnGA and JM3-ZnGA was about 5%higher than that of the traditional ZnGA.The 5%weight loss temperature(T_d,-5%)increased by about 20?.(2)The synthesis of zinc glutarate nanocatalysts(denoted as NM-ZnGA)was carried out by the solvothermal method.NM-ZnGA showed regular nanosheet morphology with larger grain size and higher crystal perfection compared with ZnGA synthesized by the conventional method.The catalytic efficiency of the ZnGA was23.8 g PPC/g ZnGA before purification and 17.1g PPC/g ZnGA after purification.The catalytic efficiency of the NM-ZnGA was 28.5 g PPC/g ZnGA before purification and20.0 g PPC/g ZnGA after purification.The yield of PPC obtained by the NM-ZnGA was about 10-15%higher than that of PPC when the conventional catalyst was used.The PPC synthesized by NM-ZnGA catalyst exhibited similar properties to that of PPC synthesized by the conventional method.Meanwhile,the effect of CO₂ pressure on the copolymerization reaction was investigated,and the carbonate linkage content decreased as the CO₂ pressure reduced.In the synthesis,the CO₂ pressure was generally controlled in the range of 3-5 MPa.In addition,it was found that NM-ZnGA could have a catalytic efficiency of 20.8 g PPC/g catalyst even at a lower CO₂ pressure of 3 MPa.Lipid droplets(LDs)play a very important role in organisms and are important biomarkers for many diseases.Real-time location and tracking of lipid droplets to diagnose related diseases early and clarify their physiological effects is a challenging task,and it is necessary to study.Among them,the fluorescent imaging of lipid droplets with organic dyes is a very promising method.Commercial fluorescent dyes such as Nile Red and Oil Red(OA)have been widely used for lipid droplet imaging.However,the low signal-to-noise ratio and large interference of fluorescence imaging have become its shortcomings that cannot be ignored.Based on this,we constructed a TPETA fluorescent molecule through tetraphenylethylene,specifically imaged lipid droplets,and tracked and detected the movement of lipid droplets.TPETA has good AIE characteristics in solution and good piezoelectric and acid-induced discoloration characteristics under solid state conditions,which can provide a possibility for AIE materials for multi-functional applications.