Energy barriers to changes microstructure dictates the time dependent behavior of materials. Hard materials have the energy barrier much higher than the energy of thermal fluctuation at room temperature. Consequently, typical behavior of hard materials at room temperature (e.g. elasticity and plasticity) is rate independent. On the contrary, soft materials have the energy barriers comparable to the energy of thermal fluctuation. Consequently, soft materials are known for complex time dependent behaviors such as viscoelasticity, swelling, and stimuli-responsiveness. Properly managed relaxation behavior underlies both the manufacturing and the operation of functional soft structures.
- Liu, Q., & Parker, K.K. (2018). A viscoelastic beam theory of polymer jets with application to rotary jet spinning. EXTREME MECHANICS LETTERS, 25, 37-44. doi: 10.1016/j.eml.2018.10.005.
- Brassart, L., Liu, Q., & Suo, Z. (2018). Mixing by shear, dilation, swap, and diffusion. JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, 112, 253-272. doi: 10.1016/j.jmps.2017.12.008.
- Brassart, L., Liu, Q., & Suo, Z. (2016). Shear, dilation, and swap: Mixing in the limit of fast diffusion. JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, 96, 48-64. doi: 10.1016/j.jmps.2016.06.013.
- Liu, Q., Huang, S., & Suo, Z. (2015). Brownian Motion of Molecular Probes in Supercooled Liquids. PHYSICAL REVIEW LETTERS, 114(22). doi: 10.1103/PhysRevLett.114.224301.