聚合物PLL-g-PEG构象变化对宏观摩擦学性能的影响

Effect of Polymer PLL-g-PEG Conformation on Macro-Tribological Properties

通过将聚赖氨酸-聚乙二醇(PLL-g-PEG)加入至不同体积分数的HEPES-甘油混合溶液中来改变聚合物的构象,研究其构象变化对摩擦性能的影响.利用晶体微量天平(QCM)定量表征了不良溶剂(甘油)的加入所导致聚合物刷构象发生的改变;摩擦试验结果表明在良性溶剂(HEPES)中聚合物刷高度水化作用对于摩擦磨损性能的改善起主导作用,而不良溶剂中起决定作用的是甘油的黏度效应;利用纳米级光干涉薄膜测量装置试验证实了表面修饰聚合物刷后的钢球-玻璃盘界面间的成膜特性既与聚合物刷的构象变化相关,也与流体动压效应相关,且随卷吸速度的改变二者对接触区内成膜的贡献会发生转变;对二者共同作用下的水基润滑机理进行了初步探讨,这对于拓宽水基润滑的应用具有较为重要的意义.

It was designed to change polymer conformation by adding poly(L-lysine)-g-poly(ethylene glycol)(PLL-gPEG)to 3 HEPES-glycerol solutions mixed with different volume ratio glycerol in this work for studying the effect of polymer conformation on tribological performance.Conformation change of polymer PLL-g-PEG was quantitatively characterized.Quartz Crystal Microbalance(QCM)was used to quantitatively characterize the change of polymer brush conformation with the addition of poor solvents.The results showed that the highly hydration effect of polymer brushes in good solvents played a critical role in improving the friction and wear,while the viscosity effect of glycerol was dominated in poor solvents.It was verified by nano-scale optical interference thin film measurement device that filmforming properties in the gap between the steel ball and glass disk,which were both grafted by polymer brush,was determined by both hydration effect induced by conformational change of the polymer brush and hydrodynamic effect.And the influence of hydration effect and hydrodynamic effect on film formation in contact changed with entrainment velocity.The water-based lubrication mechanism under the combined effect of the two was preliminary probed,which was very important for broadening the application of water-based lubrication.