The photo-induced cis-trans isomerization of azobenzene molecules, known for their significant color changes, is extensively utilized in the functional modification of polymeric materials. However, the research on the functionalization of biomass-based polyesters with azobenzene is limited. A key raw material for biomass-based coatings possess reactive double bonds and excellent film-forming capabilities, offering significant advantages for azobenzene functionalization in biomass-based polyester applications. In this study, AESO served as the polyester matrix and acrylate azobenzene derivatives as the functional molecules. Under ultraviolet radiation, AESO underwent a carbon–carbon crosslinking reaction with the azobenzene derivatives to synthesize a novel resin. The coating of this resin on a PET substrate exhibited excellent pencil hardness (3B), adhesion (5B), and solvent resistance. By alternating exposure to ultraviolet and blue light, the coating displayed reversible switching between cis and trans isomers, enabling reversible writing and erasing of patterns. Even after 20 cycles of writing and erasing, high-resolution patterns could still be observed (clearly visible under a 12x microscope). Furthermore, the image could be retained for up to 2 h under sunlight irradiation. This study presents a new method for functionalizing biobased polyesters.
Xiaochao Zhang,Jiabing Wei,Guangmin Ren,Changming Zhang,Zhanfeng Zheng,Caimei Fan
This work reported for the first time a systematic investigation on a BiOBr photocatalyzed oleic acid isomerization process in different (air, N2 and O2) atmospheres and proposed the cis–trans isomerization mechanism to effectively restrain the formation of trans fatty acids with deleterious effects on human health. The phase structures, optical properties, and morphologies of as-prepared BiOBr were characterized by XRD, UV-vis DRS, SEM and TEM. Besides, the photocatalyzed isomerization products over BiOBr in different atmospheres were analyzed with FT-IR and 1H NMR for comparison. The results demonstrate that there are significant differences in the photocatalytic isomerization process of oleic acid in different atmospheres, and especially the N2 atmosphere is the most favorable atmosphere, while the presence of O2 will inhibit the formation of elaidic acid. Moreover, density functional theory (DFT) was employed to calculate the charge density and energy difference of ground states between cis- and trans-isomers of oleic acid. Combining the theoretical and experimental findings, the radical cation and photo-induced h+ action mechanisms in the photocatalytic isomerization process were discussed and proposed. Our findings should provide new insights and basic data for understanding the photocatalytic isomerization of unsaturated fatty acids.
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