Particle surface engineering at the nano-micro scale interfaces of metal-nonmetal bonded polymeric coatings: experimental and <i>in silico</i> evaluations

Polyvinyl alcohol (PVA) is a well-known and cost-effective synthetic polymer that offers a variety of applications, including medical, food, aerospace, automotive, and material industries, for the construction of structures. However, the weak adhesion, low wear resistance, and mechanical properties of PVA usually limit their functionality and durability. Herein, the strength and bonding of the polymeric matrix were enhanced by metallization and reinforcement of carbonaceous allotropes. The nickel and diamond-containing PVA coating (PVA-Ni-D) was found to be the most wear-resistant coating with the lowest wear rate (7.34 × 10^-3 mm³), reduced penetration depth (19.2 μm) and highest scratch hardness (4.92 GPa) compared to the carbon nanotubes (PVA-Ni-CNT) and graphene (PVA-Ni-Gr)-containing composite coatings. The significant enhancement in the wear resistance of the composite coatings was further linked with the contact depth, contact radius and shear stress, as calculated by different theoretical models. The results from the interfacial interaction estimation demonstrated a strong strengthening of the diamond particles with the matrix due to particle-matrix interaction. Meanwhile, the large surface area per unit volume (in the case of CNT and graphene) results in inter-particle interactions, followed by easy sliding of these reinforcements from the matrix, which causes decreased mechanical strength and tribological performance. Density functional theory (DFT) was used to perform electronic structure calculations on the metallized polymeric composite models (two configurations were used), and the <i>in silico</i> research seemed to promote relevant and evocative outputs for the diamond-encapsulated PVA-Ni system. Therefore, the improved strength and bonding of the PVA-Ni-D coating make it a promising composite coating for multi-functional applications in materials industries.