Design, Synthesis And Properties Of Polycarbonate Materials Based On Citric Acid

Polycarbonates refer to the polymers containing carbonate groups in its molecule chain.According to the kinds of repeated units,polycarbonates can be divided into aliphatic,aromatic,aliphatic-aromatic polycarbonates and so on.Polycarbonates possess excellent thermal stability and mechanical properties,and have been widely applied to construction,transportation,medical treatment,electronics and other industries.However,the monomers of aromatic-containing polycarbonates are mostly derived from the unnewable resources.According to the statistics from some relative organizations,the amount of petroleum remaining on the Earth could be only used for 60 years.Moreover,the over-utilization of oil has caused serious pollution to the environment.Therefore,in order to reduce the consumption of oil and the pollution to environment,we should try our best to search and use the renewable resources to substitute the oil resources.1.We developed a bicyclic diol octahydro-2,5-pentalenediol（OPD）via Weiss-Cook condensation and reduction reactions from dimethyl 1,3-acetonedicarboxylate（DAC）and glyoxal.In order to obtain copolycarbonates with satisfactory molecular weights,OPD was firstly converted to octahydro-2,5-pentalenediol bis（methyl carbonate）（OPBMC）by reacting with dimethyl carbonate.Subsequently,OPBMC was melt polymerized with several linear and cyclic diols.The absolute stereochemistry of OPBMC was confirmed by NMR and single crystal X-ray diffraction.The chemical structure,thermal properties and crystal structure analysis of the PCs were characterized by NMR,FT-IR,TGA,DSC and WAXD,respectively.In a word,we conclude that the OPD shows sufficient hardness and thermal stability,and can play an important role in the polymerization field as a rigid monomer.2.According to the rigid bicyclic structure,we speculated the polycarbonates based on OPD posess high T_g and brittleness.To increase the toughness of OPD-based polycarbonates,a series of copolycarbonates were sythesized with diphenyl carbonate by melting polycondensation from OPD and hydroxyethylated bisphenol A（HBPA）in different molar ratios.The chemical structures of obtained polymers were characterized by FT-IR,¹H and ¹³C NMR spectroscopy.In addition,DSC,TGA and tensile testing were carried out to analysize the thermal and mechanical properties of polycarbonates.The results showed that the OPD can increase the toughness of polymers and remain a higher glass transition temperature at the same time.