Symmetrical “Sandwich” Polybutadiene Film with High-Frequency Low Dielectric Constants, Ultralow Dielectric Loss, and High Adhesive Strength

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To solve film formation and creep of nonvulcanized polybutadiene liquid rubber, it was designed and fabricated as a thermosetting, transferable, and symmetrical “sandwich” structure adhesive film through solution coating processing. The adhesive failure evolved from an independent cohesive failure or interfacial failure to a randomly staggered interfacial failure. According to the molecular dynamic simulation, compared to the molecular structure of 1,4-polybutadiene, the isolated π electron cloud of the vinyl side chain of 1,2-polybutadiene can form “chemical-like bonding” with the outer electrons of copper atoms. Meanwhile, the peel strength of the surface-modified polybutadiene adhesive (28.16 N/25 mm) was about three times that of the untreated one (10.11 N/25 mm), and its dielectric properties (ε′ = 2.416 and tan δ = 0.0026) maintained an ultralow level at 10 GHz, which was mainly decided by the electronic and atomic polarization of vinyl. This strategy was helpful to develop a processing method for the adhesive film of nonvulcanized liquid rubber and apply to high-speed signal transmission.