A synergistic compatibilization strategy for NBR/PA6 blends with ethylene–butadiene–fluorostyrene multiblock terpolymers

Abstract

Nitrile rubber (NBR) offers exceptional oil resistance and high elasticity, while polyamide 6 (PA6) provides outstanding mechanical strength and thermal stability; therefore, blending them allows the synthesis of high-performance blends for advanced engineering applications, but the strategy suffers from the inherent thermodynamic immiscibility and obvious phase separation. Herein, we report the preparation of ethylene–butadiene–para-fluorostyrene (E–BD–S^F) multiblock terpolymers via coordination polymerization using thioanisole ligated lutetium complexes. The terpolymers strategically incorporate para-fluorostyrene (S^F) units capable of forming hydrogen bonds and dipole–dipole interactions with PA6, along with ethylene (E) units that enhance chain entanglement, while the consecutive butadiene (BD) segments are intrinsically compatible with BD-enriched NBR to co-form covalent sulfur-anchored bridges during the vulcanization process. With the addition of 1.5 wt% E–BD–S^F, the compatibilized NBR/PA6 blends show remarkable mechanical properties, where the elongation at break doubles to 235 ± 10.60%, the tensile strength reaches 17.86 ± 0.45 MPa, and the tear strength enhances to 66.06 ± 7.14 kN m⁻¹ with improved thermal stability, while the excellent solvent resistance is maintained. This work presents a synergistic compatibilization approach based on multiblock terpolymers that integrate physical interactions with chemical bonding, providing a versatile platform for the development of high-performance polymer blends.