Preparation And Characterization Of New Ester Group-containing Polyimide

There has been a long history of development that polymer used as materials, andpolymer’s dosage has surpassed metal materials. Polyimide materials is a kind ofexcellent special heat-resistant polymer materials with a variety of preparationmethods, a variety of processing molding channels, applications in many fields.Especially in the aerospace and microelectronics polyimide has a huge applicationpotential, that it can be used as a flexible printed circuit board, adhesive tape,insulation insulation, cable package and install a solar sail, etc. There are many typesof polyimide products, and thin film material is the most widely used. Thin filmmaterial has become the main form of manufactured goods of polyimide materialsbecause of its irreplaceable advantages. Polyimide film is generally made of aromaticdianhydride and diamine by polycondensation, then through casting method orstretching process obtained the final film materials. Polyimide film has goodcorrosion resistance, also is not easy to melt and burn.However, with the rapid development of human society and technology, morerequirements have been proposed to meet people’s need. Actually modification ofpolyimide materials is never stoped: the introduction of flexible groups or side groupsto improve their toughness and solubility; the introduction of rigid groups to improveits heat resistance and stability; stretching process to improve the mechanicalproperties of the film and so on. After a lot of research,we found that polyimidematerial has better modulus and strength, heat resistance and dimensional stabilitythat molecular chain line is strong and rigidity.We intuoduce easter-group into the main chain of polyimide to enhence the lineararray of polymer molecular chain. Then we obtain high glass transition, highmechanical properties and thermal performance, low expansion coefficient and thewater absorption of polyimide materials. We choose two diamine named the APAB and BPTP who containing an ester group react with the PMDA, s-BBDA and ODPAdianhydride synthesized a series of novel polyimide material by the two-step method.Then we test the thermal properties, mechanical properties, flame retardancy and lighttransmittance properties of the polymer. The introduction of the ester group structurehas not much effect on the conventional thermal stability of the polyimide, and stillhaving a good heat resistance. But the polymer has a glass transition temperature thereis greatly improved, while the water absorption of the thin film material is also muchlower than the ordinary polyimide material, and has a very good moisture resistance.The test of the linear expansion coefficient of the polymer Indicates that the introduceof the ester group enhanced the dimensional stability of the polyimide film, so weobtain a film materia that CTE lower than the copper foil CTE (17.7ppm/K) tomeet the flexible printed circuitthe board requires the performance of the material.These superior performance is primarily due to the structure of the ester group in themolecular chain has played the role of a crank shaft, so that the molecules of thepolymer chain can be better arranged linearly, and has a strong force. But good lineararrangement of the molecular chains in the polymer has been the presence of thecrystallization unit, which also allow the polymer to obtain a glass transitiontemperature of500℃or above. The polymer also have a glass transition temperaturesurpass500℃because of the presence of the crystallization unit. Rigidity of themolecular chain line led to obtain a thin film material toughness, so we also added aflexible diamine4,4’-ODA is modified, synthesized a series of copolymerized imide.Experimental results show that, after copolymerization of the polyimide film onlyinherited homopolymerization film excellent performance, while toughness has alsobeen largely improved, prepared showing high modulus, high strength and low CTE,low water absorption and resistancefuel novel polyimide film.