Xylem fiber-wrapped organogel improved lubrication performance of epoxy coatings under dry and wet conditions

Abstract

Conventional oil-based microcapsules face critical limitations such as lubricant leakage and instability in humid environments, leading to diminished durability and performance. To overcome these challenges, this study develops a novel epoxy (EP) composite coating incorporating xylem fiber-wrapped polyacrylamide (XFP) organogel particles. The XFP organogel, synthesized via solvent co-absorption and physical isolation, encapsulates glycerol within a polyacrylamide matrix stabilized by xylem fibers. This design effectively retains glycerol within the matrix, enabling it to function as an internal lubricant that contributes to the formation of a stable lubricating film while minimizing premature dissolution in aqueous conditions. Tribological tests under dry friction revealed that the EP-XFP₂₅ coating (25 wt% XFP) reduced the friction coefficient (COF) by 77.3 % and wear rate by 77.5 % compared to pure EP, driven by glycerol lubrication and enhanced fiber flexibility. In simulated seawater, the EP-XFP₁₀ coating (10 wt% XFP) achieved a 53.4 % lower COF and 87.3 % reduced wear rate, benefiting from synergistic hydration lubrication and glycerol-seawater interactions. The XFP organogel exhibited robust thermal stability (< 120 °C) and anti-freezing properties (−40 °C), ensuring reliability in extreme environments. This work pioneers a sustainable, leakage-resistant self-lubricating coating, offering transformative potential for mechanical, marine, and aerospace applications requiring adaptive wear resistance.