Still Tim, Goodrich Carl P, Chen Ke, Yunker Peter J, Schoenholz Samuel, Liu Andrea J, Yodh A G
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA and Complex Assemblies of Soft Matter, CNRS-Rhodia-UPenn UMI 3254, Bristol, Pennsylvania 19007, USA.
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jan;89(1):012301. doi: 10.1103/PhysRevE.89.012301. Epub 2014 Jan 3.
Particle tracking and displacement covariance matrix techniques are employed to investigate the phonon dispersion relations of two-dimensional colloidal glasses composed of soft, thermoresponsive microgel particles whose temperature-sensitive size permits in situ variation of particle packing fraction. Bulk, B, and shear, G, moduli of the colloidal glasses are extracted from the dispersion relations as a function of packing fraction, and variation of the ratio G/B with packing fraction is found to agree quantitatively with predictions for jammed packings of frictional soft particles. In addition, G and B individually agree with numerical predictions for frictional particles. This remarkable level of agreement enabled us to extract an energy scale for the interparticle interaction from the individual elastic constants and to derive an approximate estimate for the interparticle friction coefficient.
采用粒子追踪和位移协方差矩阵技术来研究由柔软的、热响应性微凝胶颗粒组成的二维胶体玻璃的声子色散关系，这些颗粒对温度敏感的尺寸允许颗粒堆积分数发生原位变化。从色散关系中提取胶体玻璃的体模量(B)和剪切模量(G)作为堆积分数的函数，发现(G/B)比值随堆积分数的变化与摩擦软颗粒堵塞堆积的预测在定量上一致。此外，(G)和(B)分别与摩擦颗粒的数值预测一致。这种显著的一致性水平使我们能够从各个弹性常数中提取粒子间相互作用的能量尺度，并推导出粒子间摩擦系数的近似估计值。
