Preparation And Performance Of Frameworks Metal-Organic/Octaphenylsilsesquioxane/Polymide Composites

Polyimide（PI）has good thermal and chemical stability due to its main chain containing aromatic heterocycles,and is widely used in the field of flexible dielectric materials.The development of integrated circuits requires materials with low dielectric constant materials,which can be reduced by adding nano-hole materials in the polymer dielectric constant,but the PI itself has a high dielectric constant,and the PI dielectric constant needs to be further reduced.Zeolite ester-based imidazole skeleton materials（ZIFs）have the advantages of larger porosity and higher specific surface area.Octaphenylsesquioxane（OPS）is a compound in which the eight R groups of POSS are substituted by benzene rings and has a unique three-dimensional cage structure,which is an organic-inorganic hybrid material.Both have a pore structure and good compatibility with polymers,which can reduce the dielectric constant of PI.In this thesis,the effect of ZIFs and OPS nanoparticles on the dielectric properties of PI films was investigated by preparing composites with different mass fractions of ZIFs and OPS nanoparticles added to the PI matrix.The main research contents and conclusions are as follows:（1）ZIFs/PI composites were prepared using ZIFs as nanofillers.The ZIF-8/PI and ZIF-67/PI composites were prepared by adding ZIF-8 and ZIF-67 pretreatment solutions with different mass fractions to PI matrix for modification,and Al/ZIF-8-PI/ITO and Al/ZIF-67-PI/ITO devices were prepared by spin-coating method,respectively.The results show that the T_5%of 5 wt%ZIF-8/PI composite is 569.80℃,the dielectric constant is 2.02（1 k Hz）,the dielectric loss is 0.00551,which is 32.44%and 30.38%lower relative to PI,and the water absorption is 0.989%,which is 19.33%lower than PI;the T_5%of 7 wt%ZIF-67/PI composite is 499.96°C,with a dielectric constant of 2.03（1 k Hz）and dielectric loss of 0.008 64（1k Hz）,a decrease of 32.11%relative to PI and a slight increase in dielectric loss;the water absorption was 0.847%,a decrease of 30.91%compared to pure PI.the turn-on threshold voltage of the Al/1 wt%ZIF-8-PI/ITO device was 1.88 V and the turn-off The turn-on threshold voltage is-1.68 V,and the current switching ratio is 104 A～108 A.The turn-on threshold voltage of Al/1 wt%ZIF-67-PI/ITO device is 1.38 V,and the turn-off threshold voltage is-1.38 V,and the current switching ratio is 102 A～104 A.The current switching ratio of Al/1 wt%ZIF-67-PI/ITO device is 1.38 V,and the turn-off threshold voltage is-1.38V.（2）OPS/PI composites were prepared using OPS as nano-fillers.The modification was carried out by adding OPS pretreatment solution with different mass fractions to the PI matrix.The results showed that the T_5%of 5wt%OPS/PI composite was 505.96°C,and the dielectric constant of the composite was 2.07（1k Hz）and dielectric loss was 0.00895（1k Hz）,which decreased 30.77%and slightly increased the dielectric loss relative to that of pure PI,and the water absorption was 0.929%,which decreased 36.22%compared to PI.（3）OPS/ZIFs/PI composites were prepared using both ZIFs and OPS as nanofillers.The OPS/ZIF-8/PI and OPS/ZIF-67/PI composites were prepared by adding ZIF-8 with OPS and ZIF-67 with OPS pretreatment solution at different mass fractions to the PI matrix for modification,respectively.The results showed that the T_5%of 3wt%OPS/5 wt%ZIF-8/PI composites was 516.55℃,with dielectric constant of 1.50（1k Hz）and dielectric loss of0.00876（1k Hz）,which decreased 49.83%and slightly increased dielectric loss compared with PI dielectric constant,and water absorption of 0.842%,which decreased 31.32%compared with PI;The 5 wt%OPS/7 wt%ZIF-67/PI composite T_5%is 441.34°C,dielectric constant is 1.39（1k Hz）,dielectric loss is 0.00858,53.51%decrease in dielectric constant and slight increase in dielectric loss compared to PI,and water absorption is 0.799%,34.83%decrease compared to PI.