A facile strategy for preparing low dielectric polybutadienes with ultra-low dielectric loss and enhanced thermal stability

With the rapid development of high speed and high frequency communication, organic low dielectric (low- k ) materials with both ultra-low dielectric constant ( D k ) and ultra-low dielectric loss ( D f ) are urgently required to ensure signal transmission speed and reliability. 1,2-polybutadiene ( 1,2-PB ) is renowned for its excellent dielectric properties, making it used in high-frequency printed circuit boards (PCBs). However, its poor thermal stability and mechanical properties hinder its application which requires persistent stability. To address this issue, a series of thermal-crosslinkable benzocyclobutene (BCB)-modified PBs were synthesized through a hydrosilylation reaction. These cured PBs exhibited significantly enhanced thermal stability with the glass transition temperature ( T g ) exceeding 400 °C. In particular, they displayed ultra-low D k (2.32–2.41) and ultra-low D f (<0.001). It was found that the properties of cured PBs were related to BCB loadings. Among the cured polymers, PB- g -B 30 demonstrated the optimal dielectric properties with a D k of 2.34 and a D f of 3.6 × 10 −4 . Subsequently, a PB- g -B 30 /glass fiber laminate was fabricated, exhibiting superior dielectric and comprehensive properties when compared to commercial low- k laminates. This study provides a facile method to develop PBs with ultra-low D k and D f and enhanced thermal stability. The outstanding comprehensive properties indicate their potential as low- k materials in high-frequency communication applications.