Light-controlled friction realized by a photorheological fluid

• Published in: Tribology international 2022-12, Vol.176, p.107914, Article 107914
• Main Authors: Tang, Shuangxi, Li, Shayu, Zhu, Shicai, Ma, Liran, Tian, Yu
• Format: Article
• Language: English
• Subjects: Adsorption; Azobenzene oligomer; Friction; Photorheological fluid
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2022.107914

Intelligent friction and lubrication technologies have attracted widespread interest in the fields of surface engineering, smart fluids and mechanical transmission. Here, we show reversible light-controlled friction in a photorheological fluid composed of azobenzene oligomers. The viscosity of the azobenzene oligomer solution irradiated by ultraviolet light was 19.0% higher than that irradiated with near-infrared light. The friction coefficient upon near-infrared irradiation was up to 3.62 times that under ultraviolet light. The higher friction was ascribed to the poor film forming capacity of the photosensitive rheological fluid and the higher shear resistance of the azobenzene oligomer adsorption layer upon near infrared irradiation. This light-controlled friction and viscosity could inspire more novel applications in self-adaptive liquids, photosensitive dampers, intelligent braking and fluid pipe transportation. [Display omitted] •The feasibility of light-controlled friction and lubrication was proven due to huge friction coefficient difference (up to 3.62 times).•A group of photorheological fluid was developed by utilizing the light-induced conformation transition of azobenzene oligomers.•The viscosity of the photorheological solution irradiated by ultraviolet light was 19.0% higher than that irradiated with near-infrared light.•It inspires more valuable applications in damper and brake, pipeline transportation and self-adaptive fluid.