Exploring collagen fibers as sustainable materials for indoor humidity regulation

Leather, composed of chemically modified collagen fibers, exhibits high porosity, strong hydrophilicity, and excellent permeability, making it a promising candidate for natural humidity regulation. In this study, four types of leather were evaluated, including samples treated with inorganic and organic crosslinking agents, alongside unmodified collagen fibers as a control, to investigate their humidity regulating capabilities and underlying mechanisms. Results demonstrated that collagen fibers possess abundant functional groups, a multilayered porous structure, and remarkable thermal stability, which collectively contribute to their superior performance in humidity control. Notably, chromium-modified collagen fibers exhibited exceptional recyclability, maintaining ambient humidity levels within the ideal range of 40–60 % even under environmental relative humidity fluctuations during 30–90 %. The mechanism of humidity regulation was primarily attributed to multilayer water absorption and capillary condensation, as modelled by the modified Guggenheim–Anderson–de Boer (GAB) equation. Thermodynamic analysis revealed that the humidity-regulating process is predominantly driven by enthalpic changes. This study not only establishes collagen fibers as effective and sustainable materials for humidity control but also offers valuable insights for designing advanced humidity-regulating materials • Assessment of the humidity regulation capacity of five collagen fibers (CF). • The multilevel pore size is the key factor in humidity regulation. • Cr-CF exhibits outstanding recycling potential and humidity regulation capacity. • Humidity regulation relies multilayer water absorption and capillary condensation. • The humidity regulation process is predominantly driven by enthalpy changes.