High Performance Polyimide Films with Low D k and Low D f at 10 GHz via Cross-Linking of Bulky Pendant Groups

作者：Shiying Qi, Shuo Han, Jianhao He, Jianchao Jiang, Chi Zhang, Jun Wang, Fei Xiao, Yuanrong Cheng · 发表于：ACS Applied Polymer Materials · 年份：2025 · DOI：10.1021/acsapm.4c04123 · 被引用次数：16 · 研究领域：Synthesis and properties of polymers、Silicone and Siloxane Chemistry、Epoxy Resin Curing Processes

Herein, an effective design strategy is utilized to simultaneously reduce two difficult-to-reconcile indexes in polyimide (PI): the dielectric constant ( D k ) and dielectric loss ( D f ). It is realized by the synthesis of cross-linked PIs using a bulky and cross-linkable diamine, (4,4′-(4-(4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)phenyl)pyridine-2,6-diyl)dianiline) (TFVPPDA), featuring bulky triphenylpyridine and cross-linkable tetrafluorostyrol pendant groups. And copolymerized with 2,2′-bis(trifluoromethyl)benzidine (TFDB) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to synthesize cross-linkable PIs ( co -FPIs: co -FPI-10, co -FPI-20, and co -FPI-30) with varying TFVPPDA content. Then, cross-linked PIs ( co -FPIs-CL: co -FPI-10-CL, co -FPI-20-CL, and co -FPI-30-CL) were obtained by thermal cross-linking reactions. The cross-linked PIs with cross-linked networks possess more free volume compared with the corresponding uncured PIs, thus further reducing the D k . Additionally, cross-linked networks restrict the deflection of polar imide groups in the polymer chain, leading to a relatively low D f . More importantly, this design strategy effectively retains the excellent thermal, mechanical, and low moisture absorption properties of the PIs. Notably, co -FPI-30-CL has a low D k (2.50) and D f (0.0060) at a high frequency of 10 GHz, a glass transition temperature ( T g ) of 384 °C, a 5 wt % decomposition temperature ( T d5% ) of 566 °C, a low coefficient of th...