水润滑环境下聚合物PLL-g-PEG的宏观摩擦学性能的研究

将聚(L-赖氨酸)-g-聚(乙二醇)(以下简称PLL-g-PEG)溶解在HEPES水溶液中时，通过球-3板式摩擦试验机研究了添加聚合物PLL-g-PEG对摩擦磨损性能的影响；利用光干涉法在球-盘式纳米薄膜测量装置上初步研究了水基润滑环境下PLL-g-PEG对成膜特性的影响. 结果表明:PLL-g-PEG可降低摩擦并减小磨损，主要归因于表面接枝PLL-g-PEG后形成的一层“刷”状的水化层(Hydration)起到了良好润滑作用，且摩擦性能的改善程度主要受接触应力、卷吸速度和摩擦表面基底材料的影响. 试验过程中发现了水基润滑条件下，PLL-g-PEG聚合物刷在摩擦过程中不断遭到破坏，与此同时又快速吸附到摩擦表面上而进行“自我治愈”的行为，故而有效改善了润滑效果. 光干涉的测量结果表明:添加PLL-g-PEG后，在接枝聚合物刷的球和玻璃盘的接触面间形成了一层由聚合物刷促成的且具有一定承载能力的水化层，这层水膜保护层虽然非常薄，却可以在卷吸速度为1~64 mm/s时有效分离上下接触面从而达到良好的润滑效果. 该研究工作将为深入理解水基润滑的成膜特性及机理提供必要的支持. 

Macro-Tribological Studies of Polymer PLL-g-PEG in Aqueous Lubrication

This work aims to investigate the effects of poly(L-lysine)-g-poly(ethylene glycol) (hereinafter referred to as PLL-g-PEG) on friction and wear conducted on ball-3 plates friction testing machine, and the influences on film formation characteristics in aqueoussenvironment using a ball-disc film measuring apparatus with nanometer resolution based on optical interferometry principle, when PLL-g-PEG was added in HEPES solution. The experimental results show that PLL-g-PEG can reduce friction and wear, mainly due to a layer of hydration with" brushed”structure formed on the rubbing surfaces graftedby polymer PLL-g-PEG; andthe improvement of tribological performance mainly depended on contact stress, entrainment speed and the substrate materials. The " self-healing” behavior of PLL-g-PEG polymer brushwas reported during aqueous lubrication of a tribosystem, which meansthat PLL-g-PEG polymer brush was continuously damaged by peeled off from the surface due to rubbing,at the same time they may quickly adsorb onto the rubbing surface, thereby it can be well explained why PLL-g-PEG polymer brush can effectively improve the tribologicalproperties.It was demonstrated bytheopticalinterference results that a layer of hydrated layer, which was formedassisted by polymer brush with limitedload capacity, may appear in the gap between the steel ball and glass disk grafted by polymer brush by adding PLL-g-PEG in HEPES solution. Although this projective filmis very thin, it can effectively apart from the two rubbing interface in the contact area and then improve the lubrication properties. This research work provides the necessary support for understanding the film forming characteristics and mechanism of water-based lubrication.