Study On Novel Transparent Polyacrylonitrile-lithium Trifluoromethanesulfonate/epoxy Resin Composites With High Dielectric Constant

New concepts on flexible displays,robot sensors and electronic skins,etc.,further enhance the requirements of high dielectric permittivity?high-k?polymer matrix composites?PMCs?;in addition,they also make great demand on more and higher performances including high transparency,flexibility,mechanical strength,breakdown strength and low dielectric loss.However,it is still a great challenge to develop a multi-functional high-k composite.This thesis focuses on this challenge,its main content is divided into following two aspects.Firstly,novel multi-functional films were facilely prepared through building unique cross-linked structure based on epoxy resin?EP?and polyacrylonitrile?PAN?-lithium trifluoromethane sulfonate?LiTf?complex.Compared with high-k materials reported previously,EP/?PAN-Li Tf?films simultaneously show very high transparency,good flexibility,high tensile and breakdown strengths.For 0.22EP/?PAN-LiTf?film with 22 wt%EP,its average transmittance and elongation at break are as high as 91%?600-800 nm?and12.7%,respectively;moreover,its dielectric permittivity,AC breakdown strength and the maximum energy density are 22.1?100Hz?,41.9KV/mm and 0.172J cm^-3,about 4.9,1.8 and15.2 times of those of EP resin,respectively.completely Overcoming the disadvantages of the traditional conductors,which the addition into polymer with the breakdown strength significantly reduced.The essence of excellent comprehensive properties of EP/?PAN-Li Tf?composites was discussed.The results show that the unique structure of EP/?PAN-LiTf?composites is based on the aid of PAN,Li⁺is well dispersed throughout EP/?PAN-LiTf?films,and then an uniform and crosslinked structure with less defects can be facilely constructed.Secondly,on the premise of composites have excellent transparency,to make composites have better dielectric properties,we designed unique multi-layered composite films?EP/PAN-LiTf/EP?were fabricated through with PAN-LiTf film with special electrical conductivity as the middle layer,while EP resin as the top and bottom layers.For EP/PAN-0.5LiTf/EP film with 50 wt%LiTf,its average transmittance is as high as 90%?600-800nm?.At 100Hz,the dielectric constant and dielectric loss of EP/PAN-0.5LiTf/EP composites are 109 and 0.8,respectively,and the dielectric loss is only 0.06 times of that of PAN-0.5LiTf.The excellent dielectric properties of EP/PAN-LiTf/EP composites are attributed to the interfacial polarization of EP layer and PAN-LiTf layer,and the EP film effectively hinders the transfer of the charge at the interface between layers.EP/PAN-0.5LiTf/EP film simultaneously shows very high transparency,dielectric permittivity and low dielectric loss,completely overcoming the disadvantages induced by the addition of conductors into a polymer.This thesis provides a new idea for preparatory transparent multi-functional high-k polymer films.