Institute of Chemical Industry of Forest Products, CAF; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Province; Key Laboratory of Biomass Energy and Material, Jiangsu Province; Key Laboratory of Chemical Engineering of Forest Products, National Forestry and Grassland Administration, National Engineering Laboratory for Biomass Chemical Utilization, Nanjing 210042, Jiangsu, China.
Department of Natural Sciences, University of Michigan-Flint, 303 E. Kearsley Street, Flint, Michigan 48502, United States.
J Agric Food Chem. 2021 Sep 29;69(38):11282-11291. doi: 10.1021/acs.jafc.1c02375. Epub 2021 Sep 15.
A novel rosin-based photoresponsive anionic amphiphile, sodium -azophenyl maleopimaric acid imide carboxylate (AzoMPCOONa), has been successfully synthesized. Its molecular structure was characterized by H and C NMR and mass spectrometry (MS). The photoisomerization of AzoMPCOONa was evaluated by ultraviolet (UV)-visible spectrometry and H NMR. The structure of AzoMPCOONa could be converted between the trans and cis isomers by irradiation with UV/visible light. Importantly, a fascinating photoresponsive viscoelastic solution was prepared by mixing AzoMPCOONa and cetyltrimethylammonium bromide (CTAB). The properties of the photoresponsive viscoelastic solution were further investigated by rheology, circular dichroism (CD), and cryogenic transmission electron microscopy (cryo-TEM). Initially, the AzoMPCOONa/CTAB system was a gel-like solution composed of entangled wormlike micelles possessing the right-handed chiral structure. After UV irradiation for 10 min, the gel-like solution transformed into a slightly viscous solution, its zero-shear viscosity dramatically reduced by 2 orders of magnitude, and the aggregates were converted into rod-like micelles and spherical micelles. In addition, the right-handed chiral structure of the aggregates disappeared. These dramatic changes in the viscosity and the aggregate structure can be attributed to the photoisomerization of the azobenzene group in AzoMPCOONa, which led to changes in the molecular geometry and the packing parameter of the AzoMPCOONa/CTAB system. Interestingly, the right-handed chiral structure of wormlike micelles also is photoresponsive. The results reveal the superiority of forest resources for preparing viscoelastic solutions.
一种新型松香基光响应阴离子两亲性化合物，即对偶氮苯基马来海松酸酰亚胺羧酸钠（AzoMPCOONa），已成功合成。其分子结构通过 H 和 C NMR 以及质谱（MS）进行了表征。通过紫外（UV）-可见光谱和 H NMR 评估了 AzoMPCOONa 的光异构化。AzoMPCOONa 的结构可以通过紫外/可见光照射在顺式和反式异构体之间转换。重要的是，通过混合 AzoMPCOONa 和十六烷基三甲基溴化铵（CTAB）制备了一种迷人的光响应粘弹性溶液。通过流变学、圆二色性（CD）和低温透射电子显微镜（cryo-TEM）进一步研究了光响应粘弹性溶液的性质。最初，AzoMPCOONa/CTAB 体系是一种凝胶状溶液，由缠结的蠕虫状胶束组成，具有右手手性结构。在 UV 照射 10 分钟后，凝胶状溶液转变为略带粘性的溶液，其零剪切粘度急剧降低 2 个数量级，并且聚集物转变为棒状胶束和球形胶束。此外，聚集物的右手手性结构消失。这些粘度和聚集物结构的剧烈变化可归因于 AzoMPCOONa 中偶氮苯基团的光异构化，这导致 AzoMPCOONa/CTAB 体系的分子几何形状和堆积参数发生变化。有趣的是，蠕虫状胶束的右手手性结构也是光响应的。结果揭示了森林资源在制备粘弹性溶液方面的优越性。
