Dynamic Disentanglement Enables Highly Crystalline Fluorinated Polyimide Films Featuring Superior Dielectric Property and Intrinsic Thermal Conductivity.
The advancement of high-frequency communication and miniaturized electronics necessitates dielectric materials that combine high intrinsic thermal conductivity (λ) with low dielectric loss (Df) to mitigate signal delay and thermal accumulation. Conventional strategies, particularly nanocomposite approaches, often struggle to simultaneously achieve high λ and low Df 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 Df 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 (Td5% = 478.3°C), superior moisture resistance (water uptake of 0.41%), and good mechanical flexibility, rendering it highly suitable for advanced microelectronics.