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Efficient and reversible absorption of SO 2 in six new deep eutectic solvents (DESs) composed of levulinic acid (LA) and quaternary ammonium salts (choline chloride, CC; choline acetyl chloride, CAC; tetraethylammonium chloride, TEAC; tetraethylammonium bromide, TEAB; tetrabutylammonium chloride, TBAC; tetrabutylammonium bromide, TBAB) was systematically investigated. The molar ratio of LA to quaternary ammonium salt was fixed at 3 : 1. The results showed that all DESs possessed satisfactory performance for SO 2 absorption, with the maximum absorption capacity of 0.625 g SO 2 per g DES of LA-TEAC at 293.15 K under ambient pressure. The absorbed SO 2 was easily released by bubbling N 2 at 323.15 K and the regenerated DES was recycled five times without obvious loss of absorption performance. The solubility of SO 2 in DES of LA-CC at T = 293. 15, 303.15, 313.15, and 323.15 K under subatmospheric pressures was also determined. The relative thermodynamic parameters, i.e., absorption enthalpy, absorption entropy, and absorption Gibbs free energy, were further calculated, giving results with small negative values. The influence of water content on the SO 2 absorption was also investigated. According to NMR and FTIR analyses, the absorption of SO 2 in DES was a physical process. Moreover, all the DESs exhibited high selectivity for SO 2 /CO 2 . The present DESs are promising absorbents for SO 2 because of their high absorption capacity and good reversibility.

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Reprocessable acrylate vitrimer needs to enhance its strength to expand the application in photo-three-dimensional (photo-3D) printing. However, the methods for improving mechanical properties by the addition of nanofillers or a multifunctional resin into acrylate vitrimers are inappropriate for photo-3D printing due to the low curing speed of photopolymerization induced by weakening light transmittance or reduction of dimensional accuracy caused by large shrinkage. At present, we demonstrate a new strategy for developing a kind of mechanically robust and reprocessable 3D printing thermosets by combining hydrogen bonds and exchangeable β-hydroxyl esters into acrylate vitrimers. To realize this purpose, diacrylate prepolymer containing β-hydroxyl esters was first synthesized from glycidyl methacrylate and suberic acid. Then, the resin formulations for 3D printing comprising the synthesized diacrylate prepolymer together with acrylamide generate exchanged β-hydroxyl ester and pendent amide in cross-linked networks. Here, hydrogen bonds resulting from the amide group as sacrificial bonds dissipate vast mechanical energy under an external load. With the inclusion of 20 wt % acrylamide, the average tensile strength and Young’s modulus are up to 40.1 and 871 MPa, which increased by about 4.4 and 3.85 times, respectively. The network rearrangement of cross-linked vitrimers can be achieved through the dynamic ester exchange reactions with gradual disappearance of hydrogen bonds at elevated temperatures, imparting reprocessability into the printed structures. Various photo-3D printing or UV irradiation shapes were successfully produced, and these dissolved in ethylene glycol could be remolded again.