Because of the environmental issues associated with thermoset or network polymers, recyclable polymers are highly in demand, and the use of sustainable biomass-derived ingredients is also becoming increasingly important. In this work, we utilized 2,5bis(hydroxymethyl)furan as a starting material to produce network polyurethanes (NPUs) under facile, solvent-free (solid-state) ball milling conditions. Urethane bonds may undergo thermally controlled transcarbamoylation, a reversible dynamic covalent bond exchange, enabling reshaping of NPUs. Taking advantage of this chemistry, we demonstrate the self-healing, reprocessing, and shapememory properties of biomass-derived NPU films using mesoerythritol as a cross-linking agent. Interestingly, in urethane-bondforming reactions, the relative reactivity of the secondary alcohol group of meso-erythritol over the primary one is remarkably different in the solid state, resulting in NPU films with much enhanced mechanical properties. Dynamic mechanical thermal and stress relaxation analyses indicate that the NPU films possess typical characteristics of vitrimers, such as constant cross-link density and Arrhenius-like reduction in viscosity at elevated temperatures, even though the dissociative exchange of urethane bonds may work here. Our mechanochemical approach is facile and scalable, enabling the preparation of sustainable and recyclable polymers from various biomass-derived chemicals.

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Fe x O y H z nanostructures were incorporated into commercially available and highly porous alumina using the temperature-regulated chemical vapor deposition method with ferrocene as an Fe precursor and subsequent annealing. All processes were conducted under ambient pressure conditions without using any high-vacuum equipment. The entire internal micro- and mesopores of the Al 2 O 3 substrate with a bead diameter of ∼2 mm were evenly decorated with Fe x O y H z nanoparticles. The Fe x O y H z /Al 2 O 3 structures showed substantially high activity for acetaldehyde oxidation. Most importantly, Fe x O y H z /Al 2 O 3 with a high surface area (∼200 m 2 /g) and abundant mesopores was found to uptake a large amount of acetaldehyde at room temperature, and subsequent thermal regeneration of Fe x O y H z /Al 2 O 3 in air resulted in the emission of CO 2 with only a negligibly small amount of acetaldehyde because Fe x O y H z nanoparticles can catalyze total oxidation of adsorbed acetaldehyde during the thermal treatment. Increase in the humidity of the atmosphere decreased the amount of acetaldehyde adsorbed on the surface due to the competitive adsorption of acetaldehyde and water molecules, although the adsorptive removal of acetaldehyde and total oxidative regeneration were verified under a broad range of humidity conditions (0–70%). Combinatory use of room-temperature adsorption and catalytic oxidation of adsorbed volatile organic compounds using Fe x O y H z /Al 2 O 3 can be of potential application in indoor and outdoor pollution treatments.

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