Creation of functional tribo-surfaces using cross-interactions between molecularly thin film and surface nano-structure

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We optimize the conditions for fabricating the chemical texture and clarified the mechanism of the formation of the chemical texture. Also, we constituted a new tester for measuring the friction force on lubricant molecule-layered surface. In addition, Using the molecular dynamics simulation, we quantified surface morphology and clarified the mechanism that the surface morphology changes depending on the layering of the polar lubricant molecules. We summarize the results as follows :1) Through the observation of weting/dewetting, measurements of surface energy and spreading profiles, the relationships between the number of layers, surface energy distribution and surface stability were clarified based on the unified understandings.2) We succeeded to form nano-size concavo-convex lubricant texture by applying ultra-violet rays on a lubricant film through a mask pattern. We firstly found that such texture was formed by molecules flow from non-UV irradiated zone to UV irradiated zone, which enable us to form arbitrary shape of texture. We confirmed that texturing is possible not only polar lubricants but also non-polar lubricants.3) Using a pin-on-disk type sliding tester, depletion and replenishment characteristics of chemical textured surfaces are compared between different PFPE lubricants with and without polar end groups. We confirmed that the texturing treatment is possible not only polar lubricants but also non-polar lubricants.4) Using a coarse-grained molecular dynamics simulation based on the bead-spring polymer model, we reproduced the film distribution of molecularly thin lubricant films with polar end groups on a disk surface. We found that the film surface morphology changed periodically with the aggregation formed by inducing the polar end groups to attain more stable polar interactions.