High Thermal Conductivity Porous Organic Polymers with Low Permittivity via Desolvation-Induced Self-Assembly.

Abstract

Miniaturization of microelectronic devices demand organic dielectric polymers with ultralow permittivity (k < 2.0) and high thermal conductivity (λ > 1.0 W·m^-1·K^-1) to mitigate signal delay and thermal accumulation. However, organic polymers inherently face a trade-off: porosity reduces k but sacrifices λ due to disordered pores and interchain hopping barriers. Here, a desolvation-induced self-assembly strategy is proposed, fabricating all organic porous polyacrylonitrile (P-PAN) films. By incorporating polyethylene glycol (PEG) as a porogen and plasticizer, followed by water exchange and freeze drying, the P-PAN film features uniform microscale holes, which reduce dipole density and electronic polarization, resulting in k to 1.44 (73.1% reduction from PAN). Simultaneously, PEG-induce hydrogen bonds enable PAN chains mobility, promoting the reorganization of amorphous chains into crystalline domains during desolvation. This ordered framework facilitates efficient phonon transport via crystalline domains, elevating λ to 1.39 W m^-1 K^-1, nearly tenfold improvement over PAN (0.13 W m^-1 K^-1). Notably, P-PAN synergizes k < 2.0 and λ > 1.0 W·m^-1·K^-1 without fillers, surpassing state-of-the-art organic polymers. As a proof of concept, P-PAN as a thermal interface material (TIM) reduces chip temperature by 5.7 °C, decoupling the k-λ trade-offs in organic polymers and demonstrating its potential for flexible electronics.