Facile functionalization strategy of PBO fibres for synchronous improving the mechanical and wave-transparent properties of the PBO fibres/cyanate ester laminated composites

A copolymer of P(S-co-BCB-co-GMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization was coated on the surface of poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibres, followed by grafting 2, 2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (AHHFP) to obtain 6F-PBO@P-GMA fibres. The corresponding 6F-PBO@P-GMA fibres/modified cyanate ester wave-transparent laminated composites are then fabricated. The introduction of copolymer membrane and AHHFP reduces interfacial polarization and enhances the interfacial strength of the wave-transparent laminated composites. The corresponding flexural strength and interlaminar shear strength (ILSS) of the 6F-PBO@P-GMA fibres/modified cyanate ester wave-transparent laminated composites are 701.5 and 46.4 MPa, 19.3% and 12.9% higher than those of laminated composites reinforced by pristine PBO fibres, respectively. Meantime, the obtained wave-transparent laminated composites also possess the lowest complex permittivity, and wide high wave-transparent rate area at X-band (|T|² > 93.5%, thickness: 0–2.10 mm).