Methyl Groups Pendant on Triphenylmethane Toward Modulating Thermal Stability and Dielectric Properties of the Crosslinkable Fluorinated Polyimide Films with High Transparency  

作　　者：Wen Yang Liang Yuan Kai Gong Ruo-Han Zhang Lan Lei Hui Li 

机构地区：[1]School of Chemistry and Chemical Engineering,Shandong Key Laboratory of Fluorine Chemistry and Chemical Engineering Materials,University of Jinan,Jinan,250022,China [2]School of Materials Science and Engineering,Tianjin Key Laboratory of Composite and Functional Materials,Tianjin University,Tianjin,300350,China

出　　处：《Chinese Journal of Polymer Science》2025年第2期316-327,共12页高分子科学(英文版)

基　　金：financially supported by the Natural Science Foundation of Shandong Province(Nos.ZR2021ME055,ZR2022QB170 and ZR2022MB034);the Foundation(No.GZKF202128)of State Key Laboratory of Biobased Material and Green Papermaking,Qilu University of Technology,Shandong Academy of Sciences;the Development Program Project of Young Innovation Team of Institutions of Higher Learning in Shandong Province.

摘　　要：It is urgent to develop high-performance polyimide(PI)films that simultaneously exhibit high transparency,exceptional thermal stability,mechanical robustness,and low dielectric to fulfil the requirements of flexible display technologies.Herein,a series of fluorinated polyimide films(FPIs)were fabricated by the condensation of 5,5′-(perfluoropropane-2,2-diyl)bis(isobenzofuran-1,3-dione)(6FDA)and the fluorinated triphenylmethane diamine monomer(EDA,MEDA and DMEDA)with heat-crosslinkable tetrafluorostyrene side groups,which was incorporated by different numbers of methyl groups pendant in the ortho position of amino groups.Subsequently,the FPI films underwent heating to produce crosslinking FPIs(C-FPIs)through the self-crosslinking of double bonds in the tetrafluorostyrene.The transparency,solvent resistance,thermal stability,mechanical robustness and dielectric properties of FPI and C-FPI films can be tuned by the number of methyl groups and crosslinking,which were deeply investigated by virtue of molecular dynamics(MD)simulations and density functional theory(DFT).As a result,all the films exhibited exceptional optically colorless and transparent,with transmittance in the visible region of 450-700 nm exceeding 79.9%,and the cut-off wavelengths(λ_(off))were nearly 350 nm.The thermal decomposition temperatures at 5% weight loss(T_(d5%))for all samples exceeded 504℃.These films exhibited a wide range of tunable tensile strength(46.5-75.1 MPa).Significantly,they showed exceptional dielectric properties with the dielectric constant of 2.3-2.5 at full frequency(10^(7)-20 Hz).This study not only highlights the relationship between the polymer molecular structure and properties,but offer insights for balancing optical transparency,heat resistance and low dielectric constant in PI films.

关 键 词：Crosslinkable fluorinated polyimide Methyl group Triphenylmethane TRANSPARENCY Thermal stability Low dielectric constant 

分 类 号：O63[理学—高分子化学]