Synergistic Optimization of Thermal Conductivity and Dielectric Constant in PMMA Composites via M‐Decorated CNT Nano‐Architectures

ABSTRACT The rapid trend toward miniaturization and integration of microelectronics necessitates dielectric materials featuring both low permittivity and excellent thermal conductivity to mitigate signal delay and heat accumulation. Herein, a metal organic framework material MIL‐101(Cr)@carbon nanotube (M@CNT) coating structure is constructed by growing MIL‐101(Cr) with ultrahigh specific surface area and porosity in situ on the surface of carbon nanotubes (CNTs). In this architecture, thermally conductive CNTs are coated by an insulating MIL‐101(Cr) layer, which effectively improves their dispersion within the polymethyl methacrylate (PMMA) matrix and facilitates the formation of continuous thermal transport pathways. The prepared M@CNT/PMMA composite films exhibit a simultaneous enhancement in heat transport and dielectric performance, while maintaining their excellent electrical insulation. The thermal conductivity attains 0.296 W/(m·K), representing a 50% enhancement over pure PMMA, while the dielectric constant is reduced by approximately 22%. Furthermore, the composite films also exhibit exceptional thermal stability and good hydrophobicity. This design strategy addresses the limitation that low permittivity and high thermal conductivity are typically mutually exclusive in microelectronic systems, and establishes a robust foundation for the development of next‐generation high‐performance microelectronic packaging and advanced dielectric materials.