“Combination and complement of stiffnessand compliance” is theessence of Chinese traditional Kung Fu (e.g. Tai Chi), it is also one of the most important strategy to maintain superior mechanical performances for natural biological organisms. Although transferring this nature’s idea to synthetic structures and materials seems simple and straightforward,it has long been a challenge to manufacture nature-comparable composites with controlled combination of stiff and compliant phases. The manufacturing becomes even more challenging for interfaces and surfaces where the length scale is usually in the order of microns or less and the loadings are often the most complicated.
In view of this, Wang Zhengzhi from School of Civil Engineering, Wuhan University and his collaborators recentlydeveloped a spatially- and temporally-tunable technique for functional gradient composites using magnetic actuations. By precisely controlling the spatial distribution of nanoreinforcements inside monomeric liquid and then photopolymerizing together, composites with locally-tuned and site-specific mechanical properties were achieved. Based on this technique, Wang proposed and realized two types of biomimetic interfaces: stiff-outside-compliant-inside functional gradient coatings and compliant-outside-stiff-inside functional gradient micropillars. The former was reported to exhibit simultaneously high surface hardness, stiffness, wear-resistance, as well as good coating/substrate interfacial integrity, a combination of which is essential for protective coatings but cannot be achieved with homogeneous counterparts. The later design well resolved the conflict between contact flexibility and structural stability for adhesive pillar arrays, and consequently achieved both strong and durable bioinspired dry adhesion.
These resultsnot only deepen our understanding on the structure-property relationships for biological interfaces, it also provides a practical route to construct various bioinspired heterogeneous composites with attractive combinations of mechanical performances.
The series ofstudies have resulted in three publications respectively in the journalsMaterials Horizons (IF 13.183), ACS Nano(IF 13.709), and Small (IF 9.598). Wang Zhengzhi is the first and corresponding authors and Wuhan University is the first affiliation unit. The research was supported by the Natural Science Foundation of China (NSFC), the Natural Science Foundation of Hubei Province, and the Fundamental Research Funds for the Central Universities.
Dr. Wang Zhengzhi has been engaged in the research of multi-disciplinary and multi-scale experimental and bio-related mechanics. He joined Wuhan University in 2015 and has been currently focused on studies of dental biomechanics, polymer nanocomposites, and biomimetic micro/nanostructures.
