Research On Preparation And Properties Of Polyimide/Metal-organic Frameworks Composites

Polyimide(PI)has become one of the most promising flexible dielectric materials due to its outstanding comprehensive properties,especially its electrical insulation properties.The dielectric constant of polyimide should be further reduced in order to meet the development requirement of VLSI in microelectronics industry.Zeolite ester-based imidazole framework materials(ZIFs)have prominent pore structure,larger specific surface area,and good organic compatibility.In this paper,ZIFs/PI composites were prepared by introducing ZIFs into the PI matrix.The effects of PI repeating units and ZIFs on dielectric properties of PI were studied.With 4,4-(4,4-isopropylidenediphenoxy)bis(phthalicanhydride)(BPADA),4,4'-diaminodiphenyl ether(ODA),3,3',4,4'-biphenyltetracarboxylic dianhydride(BPDA)as monomers,BPADA-ODA-BPDA PI films were synthesysized.ZIFs/PI composite films were prepared by adding pretreated ZIFs materials into the PI.PI/ZIFs-PI/PI composite films were prepared by a three-layer compounding method.The structure of those PI films and composite films,as well as the thermal stability,water absorption and dielectric properties were studied.The results are as follows:(1)The prepared ODA-BPADA-BPDA PI had no quality loss at 450 ?.Compared with ODA-BPDA polyimide,the water absorption and dielectric constant of BPADA-ODA-BPDA polyimide were significantly decreased due to the introduction of large-volume groups on the polymer backbone.The water absorption rate of ODA-BPDA polyimide is 1.224%.Among the polyimides containing BPADA,PI(90%BPADA-ODA-10%BPDA)has the lowest water absorption,which was0.966%.When the external electric field is 1KHz,the dielectric constant of ODA-BPDA polyimide is 3.321,and among the polyimides containing BPADA,PI(70%BPADA-ODA-30%BPDA)has the highest dielectric constant,2.233,PI(50%BPADA-ODA-50%BPDA)has the lowest dielectric constant of 1.690.(2)Due to the introduction of ZIFS nanoparticles,the water absorption of polyimides decreased with the increase of ZIFS nanoparticles.The water absorption of PI was 0.896 % after the addition of 5 wt%ZIF-8 in ODA-BPDA polyimide,which was 26.765 % lower than that of pure PI,while the water absorption of PI was0.846 % when the addition of 5 wt%ZIF-67,which was 30.896 % lower than that of pure PI.In the ZIFs/PI three-layer composite,when the content of ZIF-8 was 15 wt%,the water absorption rate of PI is 0.664%,which is 45.742% lower than that of pure PI.When the content of ZIF-67 is 15 wt%,the water absorption rate of PI is The water absorption rate is 0.683%,which is 44.155% lower than that of pure PI.(3)When ZIFs nanoparticles were introduced into the polyimide matrix,the dielectric constant of the prepared ZIF-8/PI composite material decreased obviously.At the frequency of 1 KHz,the dielectric constant and dielectric loss of ODA-BPDA polyimide composites with 2 wt% ZIF-8 were 0.951 and 0.0260 respectively.The dielectric constant and dielectric loss of 2wt % ZIF-67 composite are 1.130 and0.0379 respectively.The prepared ZIF-8/PI three-layer composite material,in which the dielectric constant of the composite with 5 wt%ZIF-8 was 0.890,and the dielectric loss was 0.0202.The dielectric constant of 5 wt% ZIF-67/PI three-layer composite was 0.960 and the dielectric loss was 0.0197.The dielectric constant and dielectric loss of 2wt%ZIF-8/PI(70%BPADA-ODA-30%BPDA)composite are 1.042 and 0.0192 respectively.The dielectric constant of 2wt%ZIF-67/PI(90%BPADA-ODA-10%BPDA)composite was 1.256,and the dielectric loss is 0.0178.,2 wt % ZIF-8 / PI(10%BPADA-ODA-90%BPDA)composite dielectric constant was 1.346,dielectric loss was 0.0192.2 wt % ZIF-67 / PI(70%BPADA-ODA-30%BPDA)composite dielectric constant was 1.337,dielectric loss was 0.0247.