With the ever-increasing need of more efficient and long lasting machinery and devices, certain issues such as control of wear and fatigue of machine parts have become extremely challenging. The design of lubricating fluids able to protect surfaces against wear and high friction has been one the several tools used by engineers to improve machines’ life time. Several design strategies aimed to enhance wear protection have emerged involving polymer brushes either in their molecular form as bottle brush polymers, or grafted on the surface as polymer brush coatings. All these strategies require the lubricating or wear protecting molecules to be strongly anchored to the surfaces in order to avoid close contact between the surfaces. Strong anchoring of molecules on surfaces requires a good knowledge of the chemistry and structure of the surface which complicates dramatically the translation of these technologies towards industrial settings.<br/>We describe the design of lubricating and wear protecting fluids based on synergistic mixtures of bottlebrushes (BB) and linear polymers solutions. To illustrate this concept we used hyaluronic acid (HA) - a naturally occurring linear polyelectrolyte, and water soluble synthetic BB polymers. Individually, these two polymers exhibit poor wear protecting capabilities compared to saline solutions. Mixture of the two polymers in pure water or in saline allows to drastically increase wear protection of surfaces under a wide range of shearing conditions. We demonstrate that this synergy between the BB and HA polymer emerges from a strong, yet transient, cohesion between the two components forming the boundary film due to entanglements between both polymers. We show that this concept can be applied to other types of linear polymers and surfaces and is independent of the chemical and mechanical properties of the surfaces.

Wear protection without surface modification: Is it possible?

253rd National Meeting (2017)

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