An Epidermis-like Hierarchical Smart Coating with a Hardness of Tooth Enamel

作者：Qi, Xiaodong; Zhang, Dan; Ma, Zhongbao; Cao, Wenxin; Hou, Ying; Zhu, Jiaqi; Gan, Yang; Yang, Ming^*

来源：ACS Nano, 2018, 12(2): 1062-1073.

DOI：10.1021/acsnano.7b05478

• biomimetics
• molecular assembly
• hybrid structures
• nanocomposites
• graphene oxide
• self-healing
• mechanical properties

We overcome the fundamental dilemma in achieving hard materials with self-healing capability by integrating an epidermis-like hierarchical stratified structure with attractive mechanical and barrier properties of graphene oxide and show that such biomimetic design enables a smart hierarchical coating system with a synergetic healing effect and a record-high stiffness (31.4 +/- 1.8 GPa)/hardness (2.27 +/- 0.09 GPa) among all self-healable polymeric films even comparable to that of tooth enamel. A quasi-linear layer-by-layer (LBL) film with constituent graphene oxide is deposited on top of an exponential LBL counterpart as a protective hard layer, forming a hierarchical stratified assembly mimicking the structure of epidermis. The hybrid multilayers can achieve a complete restoration after scratching thanks to the mutual benefit: The soft underneath cushion can provide additional polymers to assist the recovery of the outer hard layer, which in turn can be a sealing barrier promoting the self-healing of the soft layer during stimulated polymer diffusion. The presenting hybridization mode of LBL assembly represents a promising tool for integrating seemingly contradictory properties in artificial materials with potential performances surpassing those in nature.

• 出版日期2018-2
• 单位哈尔滨工业大学