Synthesis, Properties And Characterization Of A Soluble And Thermo-plastic Material Poly(Ether)Imide

Poly(ether)imide (PEI) is a kind of modifed polyimide which with ether bonds in their backbones. PEI can overcome the hard-processability of common insoluble and unmelted polyimde. The general approach for desinging PEI is synthesizing by the reaction of ether bonds contained diamines or ethers bonds contained dianhydrides through one step or two steps method. In this dissertation a monomer bis (nitrophthalimide) (BNP) was synthesized, and this monomer was polymerized with sodium salt of bisphenol-A through nucleopilic aromatic displacement of nitro group. This PEI possesses improved processability meanwhile mostly maintaining their excellent thermal and mechanical properties because of the ether bonds in the backbone. From the thermal testing, the glass trasition temperature (T_g) of this PEI is 235.2℃. The temperature of 5% weight loss is 378℃. Strong polarity of the ether bonds confered good solubility to this PEI in polar solvents. Through the dynamic rheological analysis, this polymer represented excellent thermo-plastical processability.In this dissertation, a 4-nitrophthalic anhydride synthesis route from 4-nitrophthalonitrile was realized. The high efficient and low-cost 4-nitrophthalic anhydride synthesis method paved the way to synthesize PEI through the nucleophilic displacement reaction. During the tranditional process of polyimide synthesis, poly (amic acid)s is usually prepared first, and then the poly(amic acid)s is anhydrated through heating or chemical imidized method to form the polyimides. However, crosslinking reaction and incomplete anhydration (usually 50～85%) are the problems during the anhydration process, and inevitably impact properties of the resultant polymers. Because of the incomplete anhydration, water generated from the imidized reaction of the remaining poly(amic acid) during the application will make micropores in the material and low the properties of polymer. In order to overcome those drawbacks, the monomer which contains imide structure was prepared first. The monomer was synthesized by the reaction of P,P'-diamino-diphenyl-methane and 4-nitrophthalic anhydride and was imidized with acetic anhydride and pyridine as dehydrater. The monomer polymerized with sodium salt of bisphenol-A in pured andydrous DMSO, then a class of PEI was obtained, through the nitro displacement reaction, ether bonds were introduced into the backbone of PEI. During the research, we studied the preparations of the monomer synthesis and polymerization, and characterized the molecule structures of the monomer. Besides many methods of preparing sodium salt of bisphenol-A were discussed in this dissertation, finally, a high efficient and more anhydrous route was accepted.The inherent viscosity of this PEI is 0.57 dl/g (in DMF). The theory of themeasuring inherent viscosity was discussed. And molecular weight of this PEI was determinated by Gel Permeation Chromatography (GPC) analysis. The molecule structure of PEI was determinated by FTIR and ~1H NMR analysis. The state of aggregation structure of PEI was determinated by the X ray diffraction analysis. The PEI represented good thermal stability in the thermogravimetic analysis (TGA) and differential scanning calorimetry (DSC) analysis. PEI also showed good thermo-plastic processability in the dynamic rheological analysis. Solubility and solubility parameter of the polymer was studied in this dissertation.