Highly Efficient Synthesis Of Poly(Isosorbide Carbonates) Catalyzed By Ionic Liquids

Polycarbonate(PC.)is one of the most versatile engineering plastics due to its attractive properties.As the novel green media,ionic liquids(ILs)have shown great potential in catalysis owing to their tunable structures and properties.To address the problems of the usage of highly toxic phosgene,huge amount of organic solvent,endocrine-disrupting and health-threatening bisphenol-A(BPA)and environmentally unfriendly catalysts,two catalyst systems for the synthesis of poly(isosorbide carbonate)(PIC)from isosorbide and diphenyl carbonate by melt polycondensation method were developed:imidazolium inoic liquids and quaternary ammonium ionic liquids/metal compound catalysts.The main contents and results are as follows:(1)A series of green 1-butyl-3-methyl-imidazolium based inoic liquids(ILs)were successfully prepared as catalysts to synthesize PIC.By modifying the structures of ILs'anions,the molecular weight and glass transition temperature(Tg)of PIC were effectively tailored.PIC with an exteremly high number-average molecular weight(Mn)of 61,700,yield of 99%and glass transition temperature of 174 ? could be obtained catalyzed by[Bmim][CH3CHOHCOO]under the optimized reaction conditions.The anions with stronger electronegativity and hydrogen bond formation ability,were found to be more efficient.Additionally,based on the experimental results and 1H NMR spectra,a possible mechanism of cooperative nucleophilic-electrophilic activation through electrostatic interactions and hydrogen bond formation by[Bmim][CH3CHOHCOO]was proposed.(2)Four poly(aliphatic diol-co-isosorbide carbonate)s(PAICs)were also prepared by incorporating with aliphatic diols catalyzed by[Bmim][CH3CHOHCOO]to modify the flexibility of PIC.The microstructure and comonomer composition were characterized by 1H NMR and 13C NMR.The properties of PIC and PAICs were determined by DSC,TGA and DMA.The results showed that the thermal stability of PIC and PAICs incorporated by cycloaliphatic diols was better than that of PAICs incorporated by linear diols and the processibility of PAICs were much better than PIC.(3)The quaternary ammonium ionic liquids/metal compound catalysts were developed,among which[TEA][CH3COO]/LiAcac showed the best catalytic performance.The corresponding Mn of PIC could reach up to 40,100 with a yield of 95%,PDI of 1.60 and Tg of 171 ?.PAICs could also be efficiently synthesized using this compound catalysts.Among all of the copolyers,poly(1,4-butanediol diol-co-isosorbide carbonate)s(PBIC)possessed the highest Mn of 93,800 with a yield of 98%.The structure,glass transition temperature and thermal stability of PAICs were determined by NMR,DSC and TGA.