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

Polycarbonates refer to the polymers containing carbonate groups in its molecule chain,which can be classified into aliphatic,aromatic and aliphatic-aromatic polycarbonates.Among them,bisphenol A polycarbonate(BPA-PC)is widely applied in important fields such as food packaging,construction,transportation,medical and electronics due to its excellent thermal stability,transparency and mechanical properties.However,the monomer of BPA-PC is mainly produced from petroleum resources.According to the statistics from some relative organizations,the amount of petroleum remaining on the earth could be only used for 40 years.In addition,bisphenol A is a toxic hormone analog that has the risk of causing endocrine disorders and precocious puberty in infants.Therefore,many countries have banned BPA-PC in food packaging and baby bottles.Therefore,the use of renewable resources to prepare BPA-free materials is an important topic.1.We developed a rigid monomer 2,4,6,8-tetramethyl-3,7-pentalenediol(TMPD)via Weiss-Cook condensation,followed by decarboxylation and reduction reactions using Li Al H₄,starting from citric acid-derived dimethyl 1,3-acetonedicarboxylate(DAC)and glyoxal.Subsequently,the monomer TMPD was melt polymerized with1,4-cyclohexanedimethanol(CHDM)and diphenyl carbonate(DPC),affording a series of bio-based copolycarbonates with high molecular weight.The isomers of TMPD were confirmed by NMR.The chemical structures and thermal properties of the copolycarbonates were analyzed using NMR,FT-IR,TGA and DSC,respectively.Results showed that the citric acid-based monomer TMPD has good rigidity and reactivity,significantly increased the glass transition temperatures of the co-PCs.2.We developed a rigid monomer 2,2,4,4,6,6,8,8-octamethyl-3,7-pentalenediol(OMPD)via Weiss-Cook condensation,followed by decarboxylation and reduction reactions using Li Al H₄,starting from dimethyl 1,3-acetonedicarboxylate(DAC)and glyoxal.Considering the strong rigidity of the monomer OMPD,we speculated the polycarbonates based on OMPD posess high T_gs but brittleness.To increase the toughness of OMPD-based polycarbonates,OMPD was melt polymerized with1,4-cyclohexanedimethanol(CHDM)and diphenyl carbonate(DPC),affording a series of bio-based copolycarbonates.The absolute stereochemistry of OMPD was confirmed by NMR and single crystal X-ray diffraction.The chemical structures of the copolycarbonates were analyzed using FT-IR,NMR.DSC and TGA were carried out to analyze the thermal properties.Results showed that the citric acid-based monomer OMPD can maintain high thermal stability while increasing the glass transition temperatures of polymers.3.We developed a series of rigid monomers octahydro-2,5-pentalenediol(OPD),3a-methyl-2,5-pentalenediol(MPD),3a,6a-dimethyl-2,5-pentalenediol(DMPD),and3a,6a-furandiyl-2,5-pentalenediol(DFPD)via Weiss-Cook condensation reaction,followed by decarboxylation and reduction reactions using Li Al H₄,starting from dimethyl 1,3-acetonedicarboxylate(DAC)and glyoxal,pyruvaldehyde,biacetyl,furil,respectively.Subsequently,these rigid monomers were melt-polymerized with dimethyl terephthalate,dimethyl furan-2,5-dicarboxylate,and diphenyl carbonate(DPC),respectively,affording a series of bio-based(or potentially)polycarbonates with varying compositions.The isomers of OPD,MPD,DMPD,DFPD were confirmed by NMR.The chemical structures and thermal properties of the homopolymers were analyzed using NMR,FT-IR,TGA and DSC,respectively.Results showed that these citric acid based monomers significantly increased the glass transition temperatures,evidencing their prominent ability in inducing rigidity to polymers.