Cold-Sintering Preparation And Dielectric Performance Study Of Barium Titanate/Poly (Vinylidene Fluoride) Nanocomposites

With the rapid development of the electronic science,people need the electronic materials,which have high dielectric constant and low dielectric loss.Ceramic-polymer nanocomposites are a class of dielectric materials with excellent dielectric properties obtained by adding ceramic nanofillers with high dielectric constant to the polymer matrix.Directly introducing a single ceramic nanofillers into the polymer matrix can achieve the purpose of improving the dielectric constant of the composite material,but at the same time,high dielectric loss and low dielectric breakdown strength make the application value of the composite material lower.Furthermore,the traditional composite material preparation process cannot make the composite material highly dense,which further restricts the preparation of ceramic-polymer nanocomposites with high dielectric properties.In this work,two kinds of core-shell nanoparticles,inorganic material-coated barium titanate(BT)and organic material-coated BT,were introduced into the Poly(vinylidene fluoride)(PVDF)matrix as fillers,and the corresponding nanocomposites were prepared by the cold sintering process(CSP).The influence of the composition and distribution of BT filler on the electrical properties of composite materials was investigatived.The main work and research results in this manuscript include:(1)BT with particle sizes of 30 nm,100 nm and 120 nm were prepared by hydrothermal method.Three kinds of BT/PVDF composite materials with different filler sizes were prepared by CSP,and the microstructure and electrical properties of the composites were investigatived.By comparison,it was found that 100 nm BT filler has more outstanding advantages than 30 nm and 120 nm BT fillers in improving the dielectric properties of composite materials.(2)Homogeneous layer sol(HGS)was coated on the surface of BT nanoparticles to form hybrid nanofillers with core-shell structure.BT@HGS/PVDF nanocomposites were prepared by introducing BT@HGS particles into the PVDF matrix using CSP,and the microstructure and electrical properties of the nanocomposites were investigatived.The results show that BT@HGS nanoparticles are well dispersed in the PVDF matrix and improve the composite interface.When the BT@HGS nanofillers increased from 10 vol% to 50 vol%,the dielectric constant of BT@HGS/PVDF nanocomposites increased from 25.4 to 110.9,and the dielectric loss remained at a low level.BT@HGS/PVDF nanocomposites also show good temperature stability at 25-150°C and can be applied to flexible electronic components.(3)Hyperbranched polyamide(HBP)was coated on the surface of BT nanoparticles to form hybrid nanofillers with core-shell structure.BT@HBP/PVDF nanocomposites were prepared by introducing BT@HBP particles into the PVDF matrix using CSP,and the microstructure and electrical properties of the nanocomposites were investigatived.Compared with the original BT nanoparticles,the dispersion and compatibility of BT@HBP nanoparticles in PVDF have been improved to some extent.The dielectric constant of the composite material increases rapidly with the amount of BT@HBP nanofillers.For example,the dielectric constant of the composites can reach 75 at 1 k Hz room temperature when the volume fraction of BT@HBP nanofillers is 50 vol%.