Elasticity-controlled jamming criticality in soft composite solids

• Published in: Nature communications Vol. 15; no. 1; p. 1691
• Main Authors: Zhao, Yiqiu, Hu, Haitao, Huang, Yulu, Liu, Hanqing, Yan, Caishan, Xu, Chang, Zhang, Rui, Wang, Yifan, Xu, Qin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.02.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1023/1025; 639/301/923/1027; 639/301/923/1029; 639/766/530/2795; 639/766/530/2803; Biological materials; Composite materials; composites; Elasticity; Elastomers; gels and hydrogels; Humanities and Social Sciences; Inclusions; Jamming; MATERIALS SCIENCE; Mechanical properties; Mechanics; Mechanics (physics); Microspheres; multidisciplinary; nonlinear phenomena; phase transitions and critical phenomena; rheology; Science; Science (multidisciplinary); Solids; Stiffening; Tissues
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-45964-y

Soft composite solids are made of inclusions dispersed within soft matrices. They are ubiquitous in nature and form the basis of many biological tissues. In the field of materials science, synthetic soft composites are promising candidates for building various engineering devices due to their highly programmable features. However, when the volume fraction of the inclusions increases, predicting the mechanical properties of these materials poses a significant challenge for the classical theories of composite mechanics. The difficulty arises from the inherently disordered, multi-scale interactions between the inclusions and the matrix. To address this challenge, we systematically investigated the mechanics of densely filled soft elastomers containing stiff microspheres. We experimentally demonstrate how the strain-stiffening response of the soft composites is governed by the critical scalings in the vicinity of a shear-jamming transition of the included particles. The proposed criticality framework quantitatively connects the overall mechanics of a soft composite with the elasticity of the matrix and the particles, and captures the diverse mechanical responses observed across a wide range of material parameters. The findings uncover a novel design paradigm of composite mechanics that relies on engineering the jamming properties of the embedded inclusions. Soft composite solids are building blocks for many functional and biological materials, yet it remains challenging to predict their mechanical properties. Zhao et al. propose a criticality framework to connect the mechanics to the critical behaviour near the shear-jamming transition of the dispersed inclusions.