Fabrication And Properties Of Fluoride Polymer Nanocomposites With Binary Nanophases

With the development of flexible materials of electronic devices and energy storage technologies,the functional nanocomposites with high permittivity have been attracted attention in both industry and academy.At present,the common method for preparing polymer matrix with high k is to combine polymer and inorganic nanofillers with high k value.The k value of polymer matrix is low but it provides flexible and high dielectric breakdown strength of polymer composites.In contrast,inorganic nanofillers are lack of flexibility and dielectric breakdown strength with high k value.In general,high k nanofillers can be divided into two types: dielectric ceramics and conductive nanoparticles.For dielectric ceramics,it can significantly improve the k of polymer composites and keep the smaller dielectric loss,but the high content loadings lead to the deterioration in both flexibility and processability.In contract,the conductive nanofillers(such as: one dimensional carbon nanotubes(CNTs)and two dimensional graphene(GNs))show high k value and the filler loadings are not as high as ceramic to achieve enough k value.In this work,poly(vinylidene fluoride)(PVDF)and its copolymer poly(vinylidene fluorideco-chlorotrifluoroethylene)(P(VDF-CTFE))have been used as the polymer matrix to fabricate the dielectric nanocomposites by incorporation of CNTs and unsaturated ionic liquid(IL).With the electron beam irradiation(EBI)and the microphase separation of flouride polymers/IL coated CNTs compounds,we have successfully prepared the novel nanocomposites with both CNTs and organic nanodomains.The fabricated nanocomposites with binary CNTs and organics nanodomains exhibit both high dielectric properties and nice mechanical properties.The main research contents are as follows:(1)The IL in-situ grafted onto PVDF chains by electron beam irradiation in PVDF/IL blends and the following microphase separation are the new strategy to fabricate high performance PVDF materials with organic nanodomains.In order to investigate the crystallinity effects on the final morphology of the nanodomains,we have prepared the PVDF/IL blends with different PVDF crystallinities.It was found that the samples isothermal crystallized at 150 °C show highest crystallinity.However,no significant differences were observed in the final microphase separated nanocomposites.(2)The novel PVDF nanocomposites with simultaneous CNTs nanofillers and organic nanodomains have been prepared by the compounding IL coated CNTs into PVDF matrix followed by irradiation and microphase separation processes.It was found that both CNTs and IL-g-PVDF nanodomians were well dispersed in the PVDF matrix.The binary nanophases nanocomposites show high dielectric constant and low dielectric loss.Moreover,the nanocomposites are flexible and show good mechanical properties.(3)The irradiation grafting and the microphase separation behaviors of P(VDF-CTFE)/IL blends were investigated.Similar to the behaviors of PVDF/IL blends,IL can be in-situ grafted onto the polymer chains in the amorphous region.The microphase separation occurs simultaneously with the melt of the polymer matrix.The prepared nanocomposites with the organic nanodomains exhibit increased dielectric constant with limited enhanced dielectric loss.(4)The binary nanophases nanocomposites for the P(VDF-CTFE)nanocomposites were prepared using the similar strategy as the PVDF nanocomposites.IL coated CNTs have been incorporated into P(VDF-CTFE)matrix followed by irradiation and microphase separation processes.The binary nanophases nanocomposites are flexible and show excellent mechanical properties.Moreover,the nanocomposites show high dielectric performance with high dielectric constant and low dielectric loss.