Porous materials impregnated with lubricants can be used in conditions where limited lubricant is desirable. In this work, three porous polyimides (PPI) with different densities were prepared. Polyalphaolefin (PAO) impregnated PPI (iPPI) discs were rubbed against steel and sapphire balls. In operando observations of the iPPI–sapphire contacts show that oil is released under an applied load, forming a meniscus around contacts. Cavitation at the outlet is created at high sliding speeds. The amount of released oil increases with increasing PPI porosity. Contact moduli, E*, estimated based on the actual contact size show that trapped oil in iPPIs contributes to load support. At higher speeds, tribological rehydration of the contact occurs in low density iPPI, with that E* rises with speed. For high density PPIs, high speeds give a constantly high E* which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil exudation. Friction of iPPI–steel contacts is governed by the mechanical properties of the PPI, the flow of the lubricant, and the roughness of the PPI surfaces. For low- and medium- density (highly porous, high roughness) PPIs, large amount of oil is released, and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological rehydration. For high density (low porosity) PPI, with lower roughness, hydrodynamic lubrication is achieved which gives the lowest friction. Our results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness, stiffness, oil flow, and oil retentions.

浸渍有润滑剂的多孔材料可用于需要有限润滑剂的情况。在这项工作中，制备了三种不同密度的多孔聚酰亚胺（PPI）。将聚 α 烯烃 (PAO) 浸渍的 PPI (iPPI) 圆盘与钢球和蓝宝石球进行摩擦。对iPPI-蓝宝石触点的操作观察表明，油在施加的载荷下释放，在触点周围形成弯月面。高滑动速度时会在出口处产生空化。释放的油量随着 PPI 孔隙率的增加而增加。根据实际接触尺寸估算的接触模量E * 表明 iPPI 中滞留的油有助于负载支撑。在较高速度下，低密度 iPPI 中会发生接触面的摩擦再水化，其中E * 随速度增加。对于高密度 PPI，高速度会产生恒定的高E *，这受到 PPI 网络的粘弹性特性以及可能的石油渗出率的限制。 iPPI-钢接触的摩擦力由 PPI 的机械性能、润滑剂的流动和 PPI 表面的粗糙度决定。对于低密度和中密度（高孔隙、高粗糙度）PPI，会释放大量油，润滑主要通过限制在孔内接触的润滑剂以及可能的摩擦再水化来实现。对于高密度（低孔隙率）PPI，粗糙度较低，可实现流体动力润滑，从而实现最低摩擦。我们的结果表明，要实现有效润滑，聚合物多孔材料需要优化其表面粗糙度、刚度、油流动性和油保留性。