Significantly improved interfacial properties and wave-transparent performance of PBO fibers/cyanate esters laminated composites via introducing a polydopamine/ZIF-8 hybrid membrane

Polydopamine hybrid zeolitic imidazolate framework-8 (PDA*ZIF-8) membrane, synthesized by zinc nitrate hexahydrate (ZnNO₃•6H₂O), 2-methylimidazole (2-MI), and dopamine (DA), uniformly grows on the surface of poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibers by heterogeneous nucleation method to obtain PBO@PDA*ZIF-8 fibers. PBO@PDA*ZIF-8 fibers are then applied as the reinforcement, bisphenol A dicyanate ester (BADCy) as the matrix, and PBO@PDA*ZIF-8 fibers/BADCy wave-transparent laminated composites are prepared by high-temperature molding. Results indicate that PDA*ZIF-8 membrane increases the surface roughness and chemical activity of PBO fibers. The interlaminar shear strength (ILSS) and flexural strength of PBO@PDA*ZIF-8 fibers/BADCy laminated composites are 45.3 and 656.3 MPa, respectively, which are increased by 23.4% and 11.7% compared with those of PBO fibers/BADCy composites (587.4 and 36.7 MPa). The dielectric constant and dielectric loss values at 1 MHz are 2.76 and 0.0046, respectively, lower than PBO fibers/BADCy (3.06 and 0.006). At 0.3–40 GHz, PBO@PDA*ZIF-8 fibers/BADCy laminated composites have excellent wave-transparent performance (The simulated wave-transparent rate is greater than 87%, d = 1.5–3.5 mm). Meanwhile, the corresponding volume resistivity and breakdown strength are 3.7 × 10¹⁵ Ω•cm and 23.61 kV/mm, higher than PBO fibers/BADCy composites (2.2 × 10¹⁵ Ω•cm and 17.69 kV/mm), respectively.