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The tribological properties of liquid paraffin (LP) containing molybdenum disulfide (MoS 2 ) additives, including nano-balls, nano-slices, and bulk 2H-MoS 2 , are evaluated using a four-ball tribometer. Results show that all MoS 2 additives used can improve the tribological properties of LP, and that nanosized MoS 2 particles function as lubrication additives in LP better than micro-MoS 2 particles do. The LP with nano-balls presents the best antifriction and antiwear properties at the MoS 2 content of 1.5 wt%. This is ascribed to the chemical stability of the layerclosed spherical structure of nano-balls. The Stribeck curves confirm that the rotation speed of 1,450 rpm used is located at the mixed lubrication region under 300 N. MoS 2 nano-slices have small sizes and easily enter into the interface of the friction pair with a roughness of 0.032 lm, functioning as a lubricant in LP better than nano-balls do at the MoS 2 content of 1.0 wt%. The Stribeck curves also show that the differences between the two nano samples were magnified at high rotation speeds in hydrodynamic lubrication region. The application of nano-slices in high sliding speeds will be more advantageous. This work furthers the understanding of the relationship between the tribological properties and morphology of MoS 2 .

Because of their unique pendant‐side chain structures and excellent properties, zwitterionic polymers and membranes, especially zwitterionic hybrids, have attracted increasing interest in recent years. Presently, they can be potentially applied in such fields as nonlinear optical systems, ionic conduction, biomedical processing and chemical separation. In view of their significance to academia and industrial processes, this review gives a brief summary of current developments in the preparation, characterization and potential application of zwitterionic polymers and membranes. Novel approaches to prepare zwitterionic hybrids are highlighted. The present state and future perspective are also discussed. Hopefully, this review can promote the understanding of zwitterionic hybrid polymers and membranes. Copyright © 2009 Society of Chemical Industry

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