Facile Preparation\nof an Intrinsically Low Dielectric\nand High Thermal Conductivity Biobased (Magnolol) Polysiloxane Film

In\nresponse to the limitations imposed on the microelectronics\nindustry by electronic crosstalk losses and signal delays, as well\nas the rapid accumulation of heat, intrinsically low dielectric and\nhigh thermal conductivity materials are in urgent demand. Here, a\nself-curable biobased silane precursor (M@KH590) with a biphenyl unit\nwas synthesized. A series of films (magnolol polysiloxane films (MPSOs))\nwere prepared using simple sol–gel film conversion and annealing\nand modulated intermolecular forces and molecular structure. The red-shift\nof the UV–vis absorption indicated that a larger π–π\nconjugated system was established. As a result, the through-plane\nthermal conductivity of MPSO-140 was 0.601 W·m<sup>–1</sup>·K<sup>–1</sup>, which was more than three times that\nof the pure polysiloxane material. Meanwhile, MPSO-140 exhibited excellent\nintrinsic low dielectric properties (<i>D</i><sub>k</sub> = 2.52, <i>D</i><sub>f</sub> = 0.000572, and <i>f</i> = 100 MHz). This was mainly attributed to the reduction of highly\npolar substances and groups as well as the difficulty in polarizing\na π–π conjugated system. Based on rigid biphenyl\nunits and high cross-link density, the tensile strength and modulus\nof MPSO-140 were 17.42 MPa and 2.61 GPa, respectively, showing prominent\nmechanical properties. In addition, MPSO-140 exhibited excellent water\nresistance (water contact angle and 72 h water absorption of 104.8°\nand 0.19%, respectively) and electrical insulation, showing great\npotential for practical applications. The study broadened the way\ntoward overcoming the contradiction between low dielectric and high\nthermal conductivity by simultaneously introducing large free volume\nand modulating the intermolecular forces and molecular structure in\na simple and effective way.