Synthesis And Characterizatiion Of Multifunctional Polyester-polyamides Via Passerini Reaction

Passerini Three-Component Polymerization（P-3CP）is an"one-pot"method for the preparation of polyester-polyamides by using acid,aldehyde and isocyanide as monomers.It has the advantages of high atomic economy,mild polymerization conditions and simple operation.In recent years,various polyesters and polyamides with controlled structures have been developed by P-3CP,but there were few studies regarding bio-based functional polymers.In this thesis,three kinds of bio-based polyesters were designed and prepared via P-3CP using L-glutamic acid（L-GA）,isosorbide and polyethylene glycol（PEG）as bio-based raw materials.The obtained polymers have potential applications in the fields of self-degradable polymer and electrolyte matrix.The main results are as follows:1.Synthesis of functional L-glutamic acid（L-GA）-based polyesters by P-3CPA series of multifunctional polyesters were synthesized by P-3CP from L-GA,adipaldehyde and four kinds of isocyanide with different side groups.The effects of feed ratio,reaction temperature and solvent on the reaction were investigated.Their structures were characterized by nuclear magnetic resonance（NMR）,Fourier transform infrared（FTIR）spectroscopies,matrix-assisted laser desorption/ionization time of flight mass spectrometry（MALDI-To F-MS）and gel permeation chromatography（GPC）.L-GA-based polyesters with number average molar masses up to 7500 g/mol and yields up to 77%were obtained.The glass transition temperatures（T_gs）and decomposition temperature of obtained polyesters were determined by differential scanning calorimetry（DSC）and thermal gravimetric analysis（TGA）.In addition,the L-GA-based polyesters containing BOC protective group exhibited p H-responsive self-degradation properies.After acid deprotection and neutralization,the polyesters decomposed in small molecules（M_n around 300 g/mol）spontaneously via intramolecular cyclization.The degradation process was verified by ~1H NMR,liquid chromatography mass spectrometry（LC-MS）and GPC.2.Synthesis of isosorbide-based polyester-polyamide by P-3CPBased on different isosorbide-dicarboxylic acids,two synthetic routes were carried out by P-3CP:（1）polyesters were synthesized from isosorbide carboxylic acid,dialdehyde and monofuctional isocyanide;（2）polyamides were obtained using diisocyanide and monofunctional aldehyde.The reaction conditions were optimized.The chemical structures and molar masses of obtained polymers were analyzed by ~1H NMR,FTIR and GPC.The molar mass was reached 10100 g/mol,which was rarely achieved by isosorbide-based polyesters synthesized via traditional polycondensation methods.In addition,the thermal properties were investigated as well.The glass transition temperature（T_g）was 98℃,and the polymers were thermally stable below300℃.3.Preparation of high performance solid polymer electrolyte by P-3CPA series of PEG-based polyesters（PGPEs）which can be used as solid polymer electrolyte（SPE）matrix were successfully prepared by P-3CP using six kinds of carboxylated PEG with different molar masses（200,400,1000,1500,2000 and 4000g/mol）,adipaldehyde and tert-butyl isocyanide.The number averaged molar masses of PGPEs were between 14400～30200 g/mol.It was found that the side group introduced by P-3CP successfully inhibited the crystallinity of PGPEs.SPEs was prepared by mixing PGPEs with different amount of Li TFSI.The thermal properties,lithium-ion transport and conductive mechanism of the SPEs were studied by DSC,Electrochemical Impedance Spectroscopy（EIS）and FTIR.The results showed that the lithium-ion conductivity of SPE composed of PGPE-4000 and 30 wt%Li TFSI was 1.31×10^-4 S/cm at 30℃,which was nearly ten times higher than pure PEG-based SPE(1.89×10^-5 S/cm).In addition,the coordination of Li⁺with"C=O"in PGPE-based SPE has become the main mode of lithium-ion transmission,resulting in the increase of lithium-ion migration number to 0.216 and electrochemical window to 4.6V,respectively.Li Fe PO₄/Li cell battery assembled by PGPE-based SPE displayed appropriate cycle stability.After 100cycles at 0.5 C and 60℃,the specific discharge capacity was maintained 133 m Ah g^-1.In addition,the flame retardancy of PGPE-based SPE was improved due to the introduction of amide side groups.