Hybrid powder coatings (HPC) with low friction and high hardness enhance the sliding speed and allow interlocking or meshing products to slide effortlessly within each other, saving energy. In automobiles, they decrease fuel consumption and greenhouse gas emission. In the present work, a new insight of the key role played by the coverage density of triethoxyphenylsilane (TPS) grafted to SiO₂ nanoparticles over the friction coefficient, hardness, elastic modulus, and roughness of HPC is presented for the first time. In all cases, a very low amount (0.1 wt %) of functionalized or unfunctionalized SiO₂ nanoparticles were added to a powder-coating formulation based on polyester resin. HPC formulated with functionalized nanoparticles at a suitable coverage density (HPC–TPS3) exhibited significantly low friction coefficient (μ = 0.12), strong wear resistance (under dry sliding conditions at 1 and 5 N of load), low roughness (R_q = 3.5 nm), and high hardness and elastic modulus on the surface. We demonstrated that it is possible to tune the macroscopic properties by varying only the coverage density of TPS that is chemically attached to SiO₂ nanoparticles. Also, a physicochemical explanation was disclosed, wherein a hydrophilic–hydrophobic balance between −OH and phenyl groups was proposed. In all cases, the phenyl group allows the migration of functionalized nanoparticles through the polyester matrix, enhancing the hardness and elastic modulus on the surface. Thus, the functional nanomaterial design with tunable coverage density is a powerful tool to improve the physical and superficial properties of powder coatings using low amounts of nanomaterial.

中文翻译：

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优化官能团在SiO ₂纳米颗粒上的覆盖密度：迈向高强度和低摩擦的混合粉末涂料

具有低摩擦和高硬度的混合粉末涂料（HPC）可以提高滑动速度，并使互锁或啮合产品在彼此之间轻松滑动，从而节省了能源。在汽车中，它们减少了燃料消耗和温室气体排放。在本工作中，首次提出了对接枝到SiO ₂纳米颗粒上的三乙氧基_苯基硅烷（TPS）的覆盖密度在HPC的摩擦系数，硬度，弹性模量和粗糙度方面所起的关键作用的新见解。在所有情况下，极少量（0.1 wt％）的官能化或未官能化SiO ₂将纳米颗粒添加到基于聚酯树脂的粉末涂料配方中。用功能化的纳米颗粒以合适的覆盖密度（HPC–TPS3）配制的HPC表现出极低的摩擦系数（μ= 0.12），强耐磨性（在1和5 N的干滑动条件下），低粗糙度（R _q = 3.5）纳米），并在表面具有高硬度和弹性模量。我们证明，仅通过改变化学附着在SiO _2上的TPS的覆盖密度，就可以调节宏观性能。纳米粒子。另外，公开了一种理化解释，其中提出了-OH和苯基之间的亲水-疏水平衡。在所有情况下，苯基都能使官能化的纳米颗粒迁移通过聚酯基质，从而提高表面的硬度和弹性模量。因此，具有可调覆盖密度的功能性纳米材料设计是使用少量纳米材料改善粉末涂料物理和表面性质的有力工具。