Excellent Lubricating Behavior of Brasenia schreberi Mucilage

Abstract

The present work reports an excellent lubrication property of an aquatic plant called Brasenia schreberi (BS). To investigate the lubrication characteristics of the BS mucilage, a novel measuring system is designed, and an ultralow friction coefficient about 0.005 between the mucilage and glass surface has been obtained. It is found that the ultralow friction is closely related to the structure of mucilage and water molecules in the mucilage. The microstructure analysis indicates that the mucilage surrounding BS forms a kind of polysaccharide gel with many nanosheets. A possible lubrication mechanism is proposed that the formation of hydration layers among these polymer nanosheets with plenty of bonded water molecules causes the ultralow friction. The excellent lubrication property has a potential application for reducing the friction between a glossy pill coated with such layer of mucilage and people's throats.

Slippery when sticky: Lubricating properties of thin films of Taxus baccata aril mucilage

“…8 Recently, lubricity of mucilage, a seemingly opposite characteristic to its adhesive properties, has drawn an increasing interest. For example, tribological studies of the mucilage from aloe, 9 quince, 10 and Brasenia schreberi 11,12 have shown effective boundary lubrication of engineering materials, such as tungsten carbide/diamondlike carbon (WC/DLC), polyethylene/stainless steel, and self-mated quartz glass pairs. Interest in the tribological properties of mucilage is partly initiated from recent social demands of development and/or fabrication of ecofriendly lubricants.…”

“…13,14 More importantly, the lubrication mechanism of mucilage is very unique and different from conventional lubricants in many senses; while the viscosities of mucilage 15,16 are similar to conventional lubricant base stock, 17 boundary lubricating performance of mucilage is exceptionally effective between two moving surfaces. [9][10][11][12] It was observed that lubricating efficacy appears to be closely related to their wetting properties on the tribopair surfaces. For example, B. schreberi mucilage showed a coefficient of friction 0.004-0.006 between two quartz glass surfaces, and its tenacious bonding to the glass surface was proposed as a reason for extremely low interfacial friction forces.…”

Investigations of the superlubricity of sapphire against ruby under phosphoric acid lubrication

“…Kato et al obtained superlubricity between two ceramic surfaces (Si 3 N 4 /CN x /SiC) with water lubrication at a macro-scale using a traditional tribometer [15,16]. Superlubricity has also been achieved using lubricants such as glycerol (between two DLC surfaces) [17,18], a polymer brush (between two SiO 2 surfaces) [19], and plant mucilage (between two glass surfaces) [20]. In our previous work, we also obtained superlubricity between ceramic (Si 3 N 4 ) and glass surfaces lubricated by a phosphoric acid solution and mixtures of polyhydroxy alcohol and acid solutions [21][22][23].…”

Thin film lubrication in the past 20 years

“…Superlubricity achieved with such mixtures was found to be dependent on both the concentration of polyhydroxy alcohol and the number of hydroxyl groups, but not the number of carbon atoms and the arrangement of hydroxyl groups. Furthermore, superlubricity was also achieved with polysaccharide mucilage extracted from brasenia schreberi by Li et al [139]. It has been indicated that the ultra-low friction resulted from the formation of hydration layers between the polymer nano-sheets in the polysaccharide gel, as shown in Fig.…”

“…It has been indicated that the ultra-low friction resulted from the formation of hydration layers between the polymer nano-sheets in the polysaccharide gel, as shown in Fig. 27 [139]. They attribute the mechanism of liquid superlubricity to mechanical effects and chemical effects.…”