Weber Bart, Nagata Yuki, Ketzetzi Stefania, Tang Fujie, Smit Wilbert J, Bakker Huib J, Backus Ellen H G, Bonn Mischa, Bonn Daniel
Van der Waals-Zeeman Institute, IoP , University of Amsterdam , Science Park 904 , 1098XH Amsterdam , The Netherlands.
Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany.
J Phys Chem Lett. 2018 Jun 7;9(11):2838-2842. doi: 10.1021/acs.jpclett.8b01188. Epub 2018 May 16.
Measurements of the friction coefficient of steel-on-ice over a large temperature range reveal very high friction at low temperatures (-100 °C) and a steep decrease in the friction coefficient with increasing temperature. Very low friction is only found over the limited temperature range typical for ice skating. The strong decrease in the friction coefficient with increasing temperature exhibits Arrhenius behavior with an activation energy of E ≈ 11.5 kJ mol. Remarkably, molecular dynamics simulations of the ice-air interface reveal a very similar activation energy for the mobility of surface molecules. Weakly hydrogen-bonded surface molecules diffuse over the surface in a rolling motion, their number and mobility increasing with increasing temperature. This correlation between macroscopic friction and microscopic molecular mobility indicates that slippery ice arises from the high mobility of its surface molecules, making the ice surface smooth and the shearing of the weakly bonded surface molecules easy.
在很宽的温度范围内对钢与冰之间摩擦系数的测量显示，在低温（-100°C）下摩擦系数非常高，且摩擦系数随温度升高而急剧下降。只有在滑冰的典型有限温度范围内才会出现极低的摩擦。摩擦系数随温度升高而大幅下降呈现出阿仑尼乌斯行为，活化能E≈11.5 kJ/mol。值得注意的是，冰 - 空气界面的分子动力学模拟显示表面分子迁移率具有非常相似的活化能。氢键较弱的表面分子以滚动运动在表面扩散，其数量和迁移率随温度升高而增加。宏观摩擦与微观分子迁移率之间的这种相关性表明，光滑的冰源于其表面分子的高迁移率，使冰表面光滑且易于剪切弱键合的表面分子。
