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采用分子动力学方法,模拟了由脂肪酸CnH2n+1COOH和C17H35COOH(n=12,13,14,15,16,17)按1:1比例组成的7种混合单层Langmuir-Blodgett(LB)膜和由C16H33COOH分子组成的单层膜的摩擦性质.结果显示:1)随着混合单层膜内的不同分子链长差的减小,其剪切压随之减小,摩擦力主要来自单层膜间的库伦作用;2)混合膜内的两种不同分子的尾基排列对其摩擦性能影响较大,当混合LB膜中所有分子尾基全同排列时剪切压较小.当分子链长差为1个C-C键长时,分子尾基排列对膜的摩擦性质影响较大.3)同种分子尾基全同排列组成的单层膜,当上下两单层膜的尾基呈镜面对称时,其剪切压随着分子链长的增加而减小,摩擦力主要来自膜间的库伦作用;当上下两单层膜的尾基呈中心对称时,膜间摩擦力主要来自膜间的范德华(VDW)作用.
Seven hybrid monolayers of Langmuir-Blodgett (LB) membranes composed of fatty acids CnH2n + 1COOH and C17H35COOH (n = 12, 13, 14, 15, 16 and 17) in a 1: 1 ratio were simulated by molecular dynamics method The frictional properties of monolayer films composed of C16H33COOH molecules show that: 1) the shear pressure decreases with the decrease of the difference of molecular chains in the mixed monolayers, and the friction mainly comes from the monolayer (2) the tail-end arrangement of two different molecules in the mixed membrane has a great influence on the tribological properties, and the shear pressure is small when all the tail molecules in the mixed LB membrane are arranged in the same order When the difference is a CC bond length, the molecular tailing arrangement has a great influence on the frictional properties of the film.3) The monolayer films with the same tail of the same kind of molecules, when the tail groups of the upper and lower monolayers are mirror symmetry , The shear pressure decreases with the increase of molecular chain length, and the friction mainly comes from the interaction between the membranes. When the tail groups of the upper and lower monolayers are symmetric, the friction between the membranes mainly comes from the membrane Van der Waals (VDW) role.