Synthesis And Characterization Of A Photosensitive Polyimide Containing Pentadienone Moiety

Polyimides (PIs) are a kind of high-performance polymers with high thermal stability, excellent electrical insulation, inert chemical properties and good machining characteristics, which were used in many high technology areas of aviation, spaceflight, electronics, composite materials, separation membranes etc. Photosensitive polyimides (PSPIs) are double functional polymeric materials with photosensitivity and thermostability. Campared nonphotosensitive polyimids, PSPIs simplify greatly the complex, multistep processing required in high-resolution photolithography processes. Due to their excellent thermostability, high mechanical performance, outstanding electrical properties and planarization ability, PSPIs have been used as stress buffer or protective coatings for integrated circuit devices, and as interlevel dielectrics for multichip modules. Hence, PSPIs attracted increasingly worldwide attention since 1970s. Now they have been becoming current the research hotspots of organic functional materials and getting quick development.In this work, the soluble fluorinated photosensitive polyimides containing pentadienone moieties in the main chain were synthesized by the conventional two-step method. And the polymers'structures and properties were discussed. There are three parts to be included in this paper:1.1,5-dinitroaryl-1,4-pentadien-3-ones were synthesized with ultrasound irradiation in the presence of K2CO3 as catalyst. The products were characterized by elemental analysis, melting points, IR, 1H NMR and MS measurements. And the factors influencing the product yield were discussed. The results indicated that ultrasound enhanced conspicuously the reaction activity and selectivity. Compared with previous methods in the literature, the present procedure have the advantages of a short reaction period, easier work-up and as high as 88% product yield. Hence it can be used in the Claisen-Schmidt condensation reaction containing strong electron-withdrawing groups.2. The reduction of 1,5-dinitroaryl-1,4-pentadien-3-ones to the corresponding diamines were performed in hydrochloric acid using stannous chloride as reduction agent. The factors influencing the product yields were also discussed. The results show that the opitium condition of the reduction is that the molar rate of stannous chloride to 1,5-dinitroaryl-1,4-pentadien-3-one is 9, the temperature should be 80℃, the test hour is 4.5h, the yield is 91.7%. Compared with previous methods in the literature, the present procedure has the advantages of milder conditions, lower cost, easier work-up, high product yield (91.7%). The products were characterized by elemental analysis, melting points, IR, and 1H NMR measurements.3. The soluble fluorinated photosensitive polyimide (PSPI) was synthesized by 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) and 1,5-bis(3-aminophenyl-1,4-pentadien-3-one(BAPO) through two-step method. The polymer was characterized by FT-IR spectrum, 1H NMR, GPC and the properties of the polymer were also discussed. The results showed that the polymer had good solubility in organic solvents such as NMP, DMF, DMSO etc. The results also showed good heat resistance. The Tg of polyimide was 268 oC. The 5% weight loss temperature of the polymer in N2 was 467 oC and the residue weight at 800℃was 54.5%. The photosensitivity of the polymer was investigated by UV-Vis and the photolithographic conditions of polyimide photoresist are preferably defined.