Study On Synthesis,Structure And Properties Of New-type Block Polyimide

In recent decades,polyimide(PI)has an absolute dominance in many special polymers due to its excellent overall performance,wide applications,having a lot of synthetic and processing methods.At present,polyimide has been widely used in aerospace,electrical and electronic,motorcycle and precision machinery and many other areas,known as "one of the most promising engineering plastics in the 21 st century".Firstly,polyimide,synthesis of polyimide,thermal imidization of polyimide,printed circuit boards and the performance of polyimide for PCB had been summarized in this paper.The development of new materials provides the possibility of preparing printed circuit boards by Additive Process.The synthesis of polyimide based on novel monomers and its properties were studied,the molecular chain and phase separation of the polyamic acid-polyimide copolymers were also qualitatively studied during the programmed heating,we obtained the following conclusions:(1)PMA1 and PMB1 were used to successfully synthesize asymmetric ether-PM through Williamson reaction.Using PDA and ODA as diamine monomer and s-BPDA and PMDA as dianhydride monomers,the samples of PPOB had been obtained by the two-step method and the programmed heating.To satisfy the performance requirements of printed circuit board,PM10-PI,PM15-PI and PM20-PI were successfully synthesized replacing some PDA and ODA with different content PM.As an example,synthesis of PPOP-PAA had proved that the polyamic acid prepolymer synthesizing the high molecular weight polyamic acid was feasible and effective by testing the relative viscosity.(2)The samples of PPOB were analyzed by elemental analysis,TG-MS and infrared spectroscopy.During the process of programmed heating,NMP was unmixed and the imidization did not occur in the initial stage;the rate of imidization and solvent evaporation were the fastest in the 155-225 °C stage;"dynamic interruption" phenomenon appeared in the last stage;the length of time also affected the degree of imidization and solvent evaporation based on the correspondence of DTG curve and temperature curve.Analysing the solvent content and imidization degree of the samples of PPOB showed that the Tg of PAA-PI increased rapidly contibuing of imidization and solvent evaporation in the 155-225 °C stage,and the length of time also affects the Tg.The movement of molecular segments of the samples of PPOB series of were analyzed when the Tg below program temperature by XRD,and the microphase separation of the PP and OB were formed due the movement of the molecular segments by AFM.This is why that the molecular chains were regular and free to move in the 155-225 °C stage.So crystallization capacity of the block PP reached the peak and the change of microphase separation was most obvious in this stage.(3)The printed circuit board was prepared used PM10-PI through the Additive Process.The edge of the copper layer was not burred and regular,and the effect of copper plating was fine and highly selective by AFM and SEM.The principle of copper plating was described and deposition palladium of PM20-PI still get a better effect.The CTE of PPOP-PI decreased due to the introduction of block PP,and the CTE of photosentive block polyimide increased with the addition of PM.The curve of PM15-PI and PM10-PI had the inflection point at 350 °C and285 °C,it was speculated that decomposition of PM at high temperature had generated active free radicals to crosslink the polymer.The results showed that the thermal stability of the functional polyimide decreased due to the PM,it was speculated that the reason of big gap between PPOP-PI and the functional polyimides was decomposition of PMB1.Therefore,the curves of H2 O,CO,NO,CO2 and NO2 were analyzed that came from TG-MS test of PMB1 and PM10-PI,which explain the inflection point of PM10-PI and PM15-PI and proved the above speculations.Compared with “Kapton”,the dielectric constant of PPOP-PI increased due to the introduction of block PP,the dielectric constant of PM20-PI,PM15-PI and PM10-PI decreased in turn,and the down trend was related to the content of PM.