The ability to rearrange microstructures and self-stiffen in response to dynamic external mechanical stimuli is critical for biological tissues to adapt to the environment. While for most synthetic materials, subjecting to repeated mechanical stress lower than their yield point would lead to structural failure. Here, it is reported that the graphene-based polydimethylsiloxane (PDMS) nanocomposite, a chemically and physically cross-linked system, exhibits an increase in the storage modulus under low-frequency, low-amplitude dynamic compressive loading. Cross-linking density statistics and molecular dynamics calculations show that the dynamic self-stiffening could be attributed to the increase in physical cross-linking density, resulted from the re-alignment and re-orientation of polymer chains along the surface of nano-fillers that constitute an interphase. Consequently, the interfacial interaction between PDMS-nano-fillers and the mobility of polymer chain, which depend on the degree of chemical cross-linking and temperature, are important factors defining the observed performance of self-stiffening. The understanding of the dynamic self-stiffening mechanism lays the ground for the future development of adaptive structural materials and bio-compatible, load-bearing materials for tissue engineering applications.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the Air Force Office of Scientific Research (Grant No. FA9550-13-1-0084) for funding this research, and the program director Dr. Joycelyn Harrison for her guidance. L.C. acknowledges the financial support from the program of China Scholarships Council (No. 201206230164). Y.W. and Z.X. acknowledge the National Natural Science Foundation of China for the support through Grant No. 11222217. The authors thank Prof. Verduzco (Chemical and Biomolecular Engineering Department, Rice University) for helpful discussions regarding the research.
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
All Science Journal Classification (ASJC) codes
- Materials Science(all)