Synthesis And Functional Modification Of Polyetherimide

Polyetherimide(PEI)is a kind of thermoplastic polymer material with excellent properties,which has been widely used in many fields.However,the industrialization level of PEI in China is low.As an important monomer for the synthesis of PEI,the high production cost of4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhyrdride)(BPADA)needs to be solved.In addition,the development of new PEI is through the preparation of new monomers,which easily leads to the problems of long development cycle and high development cost.Therefore,exploring a simple and feasible method to prepare new PEI also has the prospect of industrial application.In this paper,BPADA was prepared by optimizing the synthesis process,and polyetherimide containing carboxyl groups in the main chain was synthesized using BPADA 3,5-diaminobenzoic acid as raw materials.Then,a series of graft modification was carried out on the polymer,the specific research work is as follows:(1)BPADA was successfully synthesized from phthalic anhydride and bisphenol A(BPA).The product was characterized by high performance liquid chromatography(HPLC),Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance(~1H-NMR).Compared with the process reported in some literature,the process steps adopted in our work are more simpler,less time-consuming and the solvent used can be recycled.The final product purity(99.7%)and yield(76.4%)were improved,which has a good industrial prospect.(2)Polyetherimide containing carboxyl group was synthesized from BPADA and 3,5-diaminobenzoic acid.The polyetherimide was grafted with N-docosanol,N-octadecylamine and L-dopa respectively,D-PEI,A-PEI and L-PEI were obtained.The structure of these polymers were characterized by FTIR and ~1H-NMR.The thermal properties of these grafted polyetherimide were investigated by TGA and DSC.The results showed that the 5%heat loss temperature of these grafted polyetherimide increased,among which A-PEI increased the most,followed by L-PEI.The glass transition temperature of these grafted polymer also increased.However,the solubility of the grafted polymer decreased.The results of common solvent test were PEI>L-PEI>D-PEI=A-PEI.The mechanical properties of these polymer decreased slightly.The hydrophilicity of the polymer changes after grafting,the water contact angles of PEI,D-PEI,A-PEI and L-PEI were 75.39°,79.75°,78.65°and68.01°respectively.The molecular weights of all polymers were determined by GPC,it was found that the molecular weight of the grafted polymers increased and the molecular weight distribution widened.PEI with Diels-Alder reaction structure was synthesized preliminarily.N-(4-hydroxy)phenyl maleimide was successfully synthesized from maleic anhydride and p-aminophenol.On this basis,N-(4-hydroxy)phenyl maleimide was reacted with furfuryl alcohol to graft PEI containing carboxyl group to obtain M-PEI with D-A structure.The structure of M-PEI was characterized by FTIR and ~1H-NMR,TGA and DSC were used to test the thermal properties of the polymer.The results showed that the thermal stability of M-PEI was improved,and the glass transition temperature was basically unchanged.The solubility of M-PEI has decreased to some extent.Compared with PEI,the mechanical properties of M-PEI have decreased.the hydrophilicity has improved.The water contact angle measuring instrument results show that the water contact angle of M-PEI is 65.62°,which means the hydrophilicity has improved.The molecular weight of M-PEI increased and the molecular weight distribution widened.