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Esterification-based post-modification for high-frequency low-Dk polyimides
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DOI：10.1016/j.polymer.2025.129506.png)
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Abstract
En 中文
To address the pressing need for low dielectric constant (Dk) materials in high-frequency communications, the development of advanced polyimides (PIs) with low-Dk has become imperative. This work utilizes a diamine monomer (PBABOH) that features a novel molecular design incorporating both a triphenylpyridine unit and pendant hydroxy groups. This monomer was then copolymerized with 4,4'-[1,4-phenylenebis(oxy)]bis[3-(trifluoromethyl)aniline] (6FAPB) and bisphenol A dianhydride (BPADA) to yield a hydroxy-functionalized PI(PIOH), achieving a preliminarily low Dk (Dk = 3.02). Moreover, the active -OH groups endowed PI-OH with efficient and straightforward post-modification capability, allowing for the regulation of PI properties by grafting functional groups. Building on this versatile platform, various fluorinated benzoyl chlorides were selected to modify PI-OH, successfully producing a series of PIs with different fluorine contents (PI-1F, PI-3F, and PI-5F). Fluorination further reduced the Dk and enhanced the hydrophobicity. Among them, PI-5F, with the highest fluorine content, significantly decreased molecular polarization, achieving a Dk as low as 2.35 at 10 GHz and water absorption merely 0.42 %. Meanwhile, the 5 % weight loss temperature (Td5 %) of PI-5F reached 419 degrees C, exhibiting excellent thermal stability and well-balanced mechanical properties. This study provides new insights into the molecular design of high-performance dielectric materials for high-frequency communication and demonstrates the flexibility and potential of post-modification strategies in the functionalization of polyimides.
Keywords:
Polyimides
Low Dk
Post-modification