Dynamics And Application Of The Active Nanoparticles In Nonequilibrium Systems

Chemically active nonequilibrium systems derived from the disciplinary fields of biology,physics and chemistry have recently attracted extensive attention.Motor proteins in eukaryotic cells convert the energy generated by the hydrolysis of adenosine triphosphate into mechanical energy for their movement,and carry substances along the cell axial filament to help meiosis and mitosis lives.Motivated by the biomolecular motors,the micro/nanomotors are studied and built,which can be used in environmental governance,biomedicine and other fields.Self-propelled micro/nanomotors which are capable for effectively converting the energy from external environment to autonomous movement.However,it is very important and difficult to design the faster nanomotor and describe the motion mechanism in detail during the driving process.In this Ph.D thesis,we are devoted to design a new motor configuration and study the driving mechanism,collective dynamics and application of micro/nanomotors in nonequilibrium systems.The research work is carried out from the following three aspects.Firstly,we propose a scheme to separate the suspending colloids by means of surfing on substrate chemical wavefronts.The previous separation technology is mainly dependent on the physical properties of the mixture.The new separation technology based on the tendency of active colloids to the substrate can be used to separate the mixtures with similar physical properties.In the beginning the active colloids and nonactive colloids are placed randomly in the solution environment.With the propagation of the chemical wave,the active colloid sensitive to the substrate is activated after encountering the corresponding substrate,and exhibited a chemotactic effect on the traveling chemical wave,resulting in their spontaneous separation from the multicomponent complex mixture via self-diffusiophoresis.In addition,the particle size also influences the separation.Because the smaller active colloid is more easily influenced by the viscous resistance and random thermal force,we can separate active colloids with different sizes by adjusting the propagation speed of the chemical wave.The mechanisms for the chemical and physical separation processes are discussed,and the implications with the reaction rate constant and particle size are also presented.Next,we use the hybrid MD-MPC simulation methods to study the dynamic behavior and self-assembly configuration of the sphere-dimer motor consisting of a noncatalytic colloid with a Janus colloid.A chemical reaction occurring on the catalytic surface of the Janus particle would create asymmetric concentration gradients,which enable the sphere-dimer motor to perform translational and rotational propulsion simultaneously.Without the consideration of hydrodynamic interaction,the dimer motors will repel each other due to the depleted force.The sphere dimers interact with each other by sensing the concentration gradient field generated by another dimer in the simulation system.Thus,the sphere-dimer motors with the same chirality assemble into stable antiparallel pairs in the system through hydrodynamic coupling and execute rotation together.Finally,we study the self-assembly behavior of a pair of self-propelled nanomotor propelling in autocatalytic chemical system.The active colloids are capable of catalyzing the solvent particles which collide with its surface,resulting in the inhomogeneous distribution of solvent particles around itself,which influences the dynamics behavior of sphere-dimer motor.By introducing reactive multiparticle collision dynamics(RMPC)to macro-control the distribution of solvent particles near the motors.It is shown that three different configurations are formed during the regulation process:Brownian dimer pair,Rotating dimer pair,and Independent dimer pair.At the end we summarize the dependence of assembly configuration on the activation environment.