Controlled-release clove oil nanocapsules integrated with cellulose nanowhiskers for durable toughening of palm leaf manuscripts

Palm leaf manuscripts (PLMs), as invaluable organic cultural heritage, are prone to embrittlement. Clove oil (CO) has traditionally been used as a toughening agent, but its high volatility limits durability. Herein, we develop a novel material comprising CO-controlled release nanocapsules, prepared via Pickering emulsion templating and solvent evaporation, using cellulose nanowhiskers (CNW) as stabilizers and polymethyl methacrylate (PMMA) as the shell. This strategy reduces CO volatilization by more than 11-fold. Applied to simulated PLMs, the material causes no visible alteration while markedly enhancing tensile strength, fracture toughness, and elongation at break by 43.5%, 101.9%, and 57.8%, respectively. Furthermore, aging tests show that the novel material maintains enhanced mechanical properties of PLMs for 4 days, while CO alone loses them after 1 day. Characterizations demonstrate that the controlled CO release, together with CNW reinforcement, provides both enhanced performance and durability. This study presents a promising strategy for the preservation of PLMs.