弹性体
共价键
光化学
激进的
化学
动态力学分析
高分子化学
流变仪
动态共价化学
硅酮
材料科学
聚合物
分子
有机化学
超分子化学
作者
Miao Huo,Jerry Hu,David R. Clarke
出处
期刊:Macromolecules
[American Chemical Society]
日期:2023-11-15
卷期号:56 (22): 9107-9116
被引量:1
标识
DOI:10.1021/acs.macromol.3c01841
摘要
PhotoCAN silicone elastomers, based on the thiol–ene reaction, exhibit rapid and reversible changes in dynamic modulus at room temperature when illuminated by UV. By combining results from magic angle spinning solid-state NMR as well as EPR and rheometry measurements, both under UV, it is concluded that the mechanical response can be attributed to a combination of dissociative, associative, and oxidation reactions. The cleavage of the C–S bonds under UV in the presence of an excess of thiyl radicals is identified as the reversible dissociative reaction responsible for abrupt drops in the storage modulus. A slower but concurrent reaction is a termination process involving thiyl radicals to form disulfide bonds. A kinetic model is developed that successfully relates the rates of the underlying reaction mechanisms to changes in the storage modulus. The results provide a basis for designing new, ambient temperature photoresponsive covalently adaptive network materials.
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