Fluid viscosity is ubiquitous property and is of practical importance in intelligent fluids,industrial lubrication,and pipeline fluid transportation.Recently,there has been a surging interest in viscosity regulation.Here,we have developed a group of photorheological fluids by utilizing azobenzene polymers with a light-induced microstructure transformation.In this work,a photosensitive polymer with 4,4'-bis-hydroxyazobenzene as the main chain was designed and synthesized as a pivotal functional material.The sufficiently large structural difference under ultraviolet and near-infrared light makes it possible to regulate the viscosity of a polyethylene glycol solution.The viscosity of the photosensitive rheological fluids under ultraviolet light radiation is found to be up to 45.1％higher than that under near-infrared light radiation.To explore this intelligent lubricating technology,the friction regulation of ceramic sliding bearings was investigated utilizing photosensitive rheological fluids.Reversible friction regulation with a ratio of up to 3.77 has been achieved by the alternative irradiation of near-infrared and ultraviolet light,which can be attributed to the differences in mechanical properties and molecular structures under ultraviolet and near-infrared light according to both simulations and experiments.Such photorheological fluids will have promising applications in controllable lubrication,intelligent rheological fluids,and photosensitive dampers.

Shuangxi TANG;Shayu LI;Liran MA;Yu TIAN

State Key Laboratory of Tribology,Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China;College of Chemistry and Chemical Engineering,Chongqing University,Chongqing 401331,China

摩擦（英文）

[1]Shuangxi TANG;Shayu LI;Liran MA;Yu TIAN-.Photorheological fluids of azobenzene polymers for lubrication regulation)[J].摩擦（英文）,2022(07):1078-1090

Photorheological,photorheological,hydroxyazobenzene

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