Interlocked silicon nitride nanowires-vertical carbon nanotubes/hydroxyapatite networks for reinforcing PEEK polymer composites

Polyetheretherketone (PEEK) is widely used in preparation of prosthesis due to excellent biocompatibility. However, the limited mechanical stability restricts the application in load-bearing bones. This study aims to develop PEEK composites for hip joint applications by integrating biological functionality with sufficient mechanical strength and biotribological properties. Here, we design an interlocked silicon nitride nanowires-vertical carbon nanotubes/hydroxyapatite network to reinforce PEEK (V-SCNT/HA-PK). Specifically, we control the vertical carbon nanotubes (V-CNT) growth on the surface of the silicon nitride nanowires (SN), forming V-SCNT network. The pulsed electrodeposition was used to induce the growth of hydroxyapatite (HA) nanosheets in the V-SCNT network to form interlocked V-SCNT/HA networks. Meanwhile, curved CNT (C-CNT) were introduced as a contrasting transition layer, facilitating the formation of C-SCNT/HA. The interlocked V-SCNT/HA networks as bioactive filler were incorporated into the PEEK matrix, forming V-SCNT/HA-PK. The interlocked V-SCNT/HA networks promote the penetration of PEEK matrix and improves the interfacial bonding and cohesive strength of the V-SCNT/HA-PK. Thus, this increases the mechanical and biotribological properties of the V-SCNT/HA-PK. Compare with the C-SCNT/HA reinforced PEEK (C-SCNT/HA-PK), V-SCNT/HA-PK have 194.17 %, 113.04 % and 113.32 % improvement in tensile strength, hardness and elastic modulus, respectively. The friction coefficient and wear rate of the V-SCNT/HA-PK reached 0.09 and 0.85 × 10⁻¹⁴ m³(N·m) ⁻¹, which is 70.00 % and 60.09 % lower than that of the C-SCNT/HA-PK. In addition, V-SCNT/HA-PK shows excellent biocompatibility and osseointegration. The present study provides a feasible interlocked V-SCNT/HA network reinforcement for enhancing the mechanical and biotribological properties of PEEK composites, which are expected to be applied in hip joint replacements.