Hybrid Polymer Membrane Functionalized PBO Fibers/Cyanate Esters Wave-Transparent Laminated Composites

Hybrid polymer membrane (TA-APTES), synthesized by tannic acid (TA) and aminopropyl trethoxysilane (APTES) based on the Schiff’s base and Michael addition reaction, is deposited on the surface of poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibers, and then grafted with epoxy-terminated polysesquisiloxane (POSS) to obtain POSS-g-PBO@TA-APTES fibers. The POSS-g-PBO@TA-APTES fibers reinforced bisphenol A dicyanate ester (BADCy) resins (POSS-g-PBO@TA-APTES fibers/BADCy) wave-transparent laminated composites are prepared. The interlaminar shear strength and flexural strength of POSS-g-PBO@TA-APTES fibers/BADCy composites are respectively enhanced from 36.7 and 587.4 MPa to 42.8 and 645.8 MPa, increased by 16.6% and 9.9% compared with those of PBO fibers/BADCy composites. At 1 MHz, the corresponding dielectric constant and dielectric loss are reduced to 2.85 and 0.0047, respectively, lower than those of PBO fibers/BADCy (3.06 and 0.006) composites. Meanwhile, the simulated wave transmittance rate of POSS-g-PBO@TA-APTES fibers/BADCy composites with the thicknesses of 1.5–3.5 mm is higher than 86.2% at 0.3–40 GHz. The volume resistivity and breakdown strength of POSS-g-PBO@TA-APTES fibers/BADCy composites are 2.8 × 10¹⁵ Ω·cm and 19.80 kV/mm, higher than PBO fibers/BADCy composites (2.2 × 10¹⁵ Ω·cm and 17.69 kV/mm), respectively. And the corresponding heat resistant index is 221.5 °C, lower than PBO fibers/BADCy composites (229.6 °C). Graphical abstract: [Figure not available: see fulltext.]