Elastic wood sponge with excellent fatigue resistance for cushioning applications

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The widespread use of petroleum-based foam materials in cushioning applications has raised increasing environmental concern, thereby accelerating the development of biomass-derived and renewable-resource-based alternatives. In this study, a hydrophilic elastic wood sponge was engineered from balsa wood through deep eutectic solvent (DES) treatment followed by PVA–CA/glycerol incorporation and thermal curing. Partial removal of lignin and hemicellulose by DES preserved the cellulose framework while increasing structural compliance, and subsequent PVA–CA/glycerol incorporation and thermal curing reinforced the cellular architecture without destroying the intrinsic honeycomb-like porous structure of the wood. As a result, the resulting elastic wood exhibited elastomer-like compressive recovery and remarkable structural stability under repeated loading. The material recovered more than 90% of its original height after severe compression and retained 88.8 ± 1.6% of its height after 500 compression cycles, demonstrating excellent elasticity and fatigue resistance. Pressure-sensitive film analysis and drop-impact tests further demonstrated the excellent dynamic cushioning performance of elastic wood, which exhibited a markedly lower cumulative film response and limited thickness reduction under repeated impacts, consistently maintained egg integrity at a drop height of 1.0 m, and outperformed the four tested commercial cushioning materials under the present 0.5 m drop-test configuration. These results indicate that regulation of the wood framework, coupled with polymer incorporation and thermal curing, offers an effective strategy for developing wood-derived cushioning materials with mechanical robustness, compression recovery, and impact-buffering capability.