Dynamic Disentanglement Enables Highly Crystalline Fluorinated Polyimide Films Featuring Superior Dielectric Property and Intrinsic Thermal Conductivity.

Abstract

The advancement of high-frequency communication and miniaturized electronics necessitates dielectric materials that combine high intrinsic thermal conductivity (λ) with low dielectric loss (D_f) to mitigate signal delay and thermal accumulation. Conventional strategies, particularly nanocomposite approaches, often struggle to simultaneously achieve high λ and low D_f without compromising processability or mechanical integrity. Herein, a semicrystalline polyimide (TAHQ/TFMB) architecture is initially established by circumventing the amorphous nature of fluorinated systems via rigid-rod backbone design and programmed thermal processing. Subsequently, minor dynamically exchangeable siloxane segments (≤ 1 mol%) act as molecular disentanglement switches, triggering topological rearrangement that promotes the formation of widely distributed crystal nuclei and enables the subsequent development of large-scale crystalline domains, ultimately yielding an enhanced crystallinity exceeding 50%. The optimally designed film with merely 0.25 mol% siloxane exhibits an enhanced in-plane λ of 2.33 W·m^-1·K^-1 and an ultralow D_f of 0.00142 at 10 GHz. This synergy facilitates the first realization of a broadband thermoacoustic generator featuring an all-organic substrate and a flexible hairpin bandpass filter with excellent signal transmission performance. Furthermore, the DBPI-0.25 film exhibits excellent thermal stability (T_d5% = 478.3°C), superior moisture resistance (water uptake of 0.41%), and good mechanical flexibility, rendering it highly suitable for advanced microelectronics.