Ying Hanze, Zhang Yanfeng, Cheng Jianjun
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 West Green Street, Urbana, Illinois 61801, USA.
Nat Commun. 2014;5:3218. doi: 10.1038/ncomms4218.
Polymers bearing dynamic covalent bonds may exhibit dynamic properties, such as self-healing, shape memory and environmental adaptation. However, most dynamic covalent chemistries developed so far require either catalyst or change of environmental conditions to facilitate bond reversion and dynamic property change in bulk materials. Here we report the rational design of hindered urea bonds (urea with bulky substituent attached to its nitrogen) and the use of them to make polyureas and poly(urethane-urea)s capable of catalyst-free dynamic property change and autonomous repairing at low temperature. Given the simplicity of the hindered urea bond chemistry (reaction of a bulky amine with an isocyanate), incorporation of the catalyst-free dynamic covalent urea bonds to conventional polyurea or urea-containing polymers that typically have stable bulk properties may further broaden the scope of applications of these widely used materials.
带有动态共价键的聚合物可能会展现出动态特性，比如自我修复、形状记忆和环境适应性。然而，目前已开发的大多数动态共价化学方法要么需要催化剂，要么需要改变环境条件，以促进块状材料中的键逆转和动态性能变化。在此，我们报告了受阻脲键（氮原子上连接有庞大取代基的脲）的合理设计，并利用它们制备出了能够在低温下实现无催化剂动态性能变化和自主修复的聚脲和聚（聚氨酯-脲）。鉴于受阻脲键化学的简单性（庞大胺与异氰酸酯的反应），将无催化剂动态共价脲键引入到通常具有稳定块状性能的传统聚脲或含脲聚合物中，可能会进一步拓宽这些广泛使用材料的应用范围。
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