High‐Performance Low‐k Poly(dicyclopentadiene) Nanocomposites as Achieved via Reactive Blending with Norbornene‐Functionalized Larger POSS.

Low dielectric constant (k) polymers with excellent comprehensive properties are useful materials in the microelectronics industry as matrix resins or encapsulation layers. With the inherent low polarization, high reactivity, good processability, and low cost, poly(dicyclopentadiene) (PDCPD) has received considerable attention as low‐k materials. However, its practical application is limited by the relatively high thermal expansion and k value. Herein, three norbornene‐functionalized polyhedral oligomeric silsesquioxanes (POSSs) with T8, T10, and T12 polyhedral cores are synthesized and employed for enhancing the dielectric and comprehensive properties of PDCPD via reactive blending. The results show that these POSSs have good compatibility with PDCPD matrix and nano‐dispersed POSSs particles could be obtained. As a result, the materials' properties can be largely enhanced by varying the POSS content and POSS size. Especially, PT12N12‐40 (40 wt% of T12N12) shows the lowest k value (2.1) and coefficient of thermal expansion (63.4 ppm°C−1), highest glass transition temperature (202.5 °C), yield strength (78.0 MPa), and elastic modulus (2.36 GPa), along with excellent hydrophobicity. This study highlights a useful strategy to fabricate high‐performance low‐k polymer nanocomposites by using larger POSS and reactive blending, which provides useful materials for the future microelectronic industry and high frequency communication. [ABSTRACT FROM AUTHOR]