Hindered urea bond for the design of dynamic materials

Dynamic covalent chemistry;Hindered urea bond (HUB);Dynamic polymers;Self-healing;Hydrolyzable;Malleable thermoset

Ying, Hanze

关键词: Dynamic covalent chemistry;    Hindered urea bond (HUB);    Dynamic polymers;    Self-healing;    Hydrolyzable;    Malleable thermoset;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/97648/YING-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Dynamic covalent bonds (DCBs) featuring reversible bonding/debonding properties have found various applications in dynamic materials designs such as self-healing, malleable, shape-memory or environmentally-adaptive materials. However, most DCBs developed so far require either catalyst or harsh environments to facilitate bond reversion and involve special building blocks for synthesis. Here we seek to develop a novel platform for dynamic materials design using a new type of DCB – hindered urea bond (HUB). Differing from normal urea bond, HUB bears bulky substituents on one of the nitrogen atom, which distorts the atomic co-planarity, weakens the bonding stability, and allows reversible dissociation of HUB to isocyanate and hindered amine. The dynamic properties of HUB enables the design of self-healing polymeric elastomers/malleable thermosets through bond exchange and hydrolyzable polymers through quenching of dissociative intermediate – isocyanate. HUB shows many advantages in dynamic materials designs compared with other DCB systems in terms of simplicity, dynamicity, tunability and cost.