Study On Self-assembly Dynamics Of Self-propelled Sphere Dimers

In biological systems,molecular machines can perform extremely complex tasks,overcoming the problems of scale,viscosity,and non-equilibrium environments.Inspired by nature,scientists are aiming to find the best architecture for the controlled motion of self-propelled nanoscale artificial objects in solutions and at interfaces.Synthetic self-propelled small swimmers can also be autonomous,converting energy available from their environment into directed mechanical motion or rotation in various ways.Recent work has addressed the physics of synthetic self-propelled motors and rotors in low-Reynolds-number chemical environments.Examples of such particles include Janus particles,nanorods,and sphere dimers,where catalytic reactions occur at specific parts of these objects.This paper first introduces the motion environment,common structure and driving mode of nanomotors.In this paper,the basic computational processes of molecular dynamics(MD)and multi-particle collision dynamics(MPC)are introduced,and the MD-MPC method is used to build the model to simulate the motion evolution process of self-assembled sphere dimers in the solution system.The dynamics of chemically powered sphere dimers at the micro-and nano-scales confined in a quasi-two-dimensional geometry are investigated.The dimer consists of a Janus particle and a non-catalytic sphere.The asymmetric distribution of the catalytic activity on the dimer gave rise to an asymmetric radient field of the product particles along and perpendicular to the internuclear bonds,which resulted in translational and rotational motion,respectively.When the concentration gradient field is fixed,the rotation speed of the sphere dimers is related to the difference of potential energy parameters between solution particles and sphere dimers.The greater the difference of energy,the greater the rotation speed of the sphere dimers will be.Due to the chemical interactions,ensembles of dimers spontaneously form anti-parallel aligned doublets that exhibit the same rotation direction and lose translational motion.The chirality of the dimer plays an important role in the process of doublet formation.The study displays new collective dynamics and structures when both translational and rotational self-propulsion occur.In this paper,we set up a particle-based model to study the dynamics of a sphere dimer that exhibited both translational and rotational motion in terms of a self-diffusiophoresis mechanism.The rotation motion of the self-assembled sphere dimer was quantitatively analyzed and it was found that the spin characteristic of the dimer motor plays an important role in the formation of the motor pair.These results have high reference value for the preparation of nanomotors with specific function in actual experiment.