The Study On Propulsion Mechanism And Collective Behavior Of Light-Driven Micromotor Based On Photothermal And Photocatalytic Material

Light-driven micromotor is a kind of micro-device that can convert light energy into motion energy of self-propulsion,exhibiting great potential in the application of active material,environmental remediation,biomedicine and environment monitoring.However,the self-propulsion of light-driven mircomotor needs relatively strong driving force,which requires the addition of toxic chemical fuels,thus limiting their application in the practical fields.In addition,the movement control method of light-driven mircomotor is complicated,which makes it difficult to precisely control its motion behavior for different applications.Hence,the current thesis focuses on the research on the propulsion mechanism and the control of motion behavior of light-driven mircomotor based on facile method,which includes the following two parts1.Light-driven PS@PDA based micromotor and its propulsion mechanism and motion control.In this work,we report a kind of infrared light driven micromotor based on polystyrene(PS)and polydopamine(PDA),which exhibits different motion behavior for a single micromotor or a group of micromotors.Under infrared red light irradiation,one single micromotor exhibits negative phototactic motion behavior while multiple micromotors exhibit positive phototatic schooling behavior.Besides,due to the interaction between polydopamine shells,the collective behavior of a group of micromotors is capable of forming controllable aggregation pattern,enabling us to accomplish in-solution painting with different structures2.Light driven C3N4/PPy based micromotor and its motion control and collective behavior.In this work,we report a kind of light driven micromotor based on photocatalytic carbon nitride(C3N4)and photothermal polypyrrole(PPy).The micromotor can sense the change in the irradiation light intensity and exhibits positive motion behavior under weak light intensity and negative motion behavior under strong light intensity.Under light irradiation,photocatalytic chemical reaction could occur on the surface of C3N4,resulting in different ion products,and the different diffusivity of the products leads to diffusiophoresis mechanism.While on the other hand,photothermal effect will occur on PPy under light irradiation,converting light energy into thermal energy,and cause the occurrence of thermophoresis mechanism.The competition between these two different mechanisms leads to the appearance of the unique reciprocating movement of a single micromotor and spinning schooling behavior for a group of micromotors under medium light intensity irradiation.