Magnetically Induced Metastable Colloidal Crystals

Colloidal crystal is one-dimensional,two-dimensional or three-dimensional ordered structure,which is assembled by colloidal particles as building blocks.In the past,more attention has been paid to the colloidal crystal structure in the stable state.However,there are few reports on the structure,properties and applications of the metastable colloidal crystals.Lack of effective and controllable metastable colloidal crystal preparation method and highly reproducible research objects are the main reasons for the slow progress of the related research.As a result,the study of metastable colloidal crystals is facing great opportunities and challenges.In this paper,the assembled system was chosen to assemble monodisperse polystyrene particles in the solution of ferrofluid.First of all,in order to obtain the photonic crystal,the structure elements need to be well dispersed,and the stability between the particles and solvents are required.In order to investigate the controlled synthesis and related properties of PS beads and Fe₃O₄,TEM,XRD,SEM,VSM,TGA,PH,surface potential measurement,electrophoresis and some other experimental characterizations are used.Through the experiments,it is concluded that the polystyrene and the magnetic fluid have good dispersibility and uniform particle size,and the surface potential is negative under different PH which is perfect for the assembly.The polystyrene in the system tends to be enriched in the direction away from the magnetic field,which leads to the formation of metastable colloidal crystal.The method of using the magnetic assembly to form the metastable colloidal crystal has the advantages of shorter time consuming and convenient compared with the evaporation and concentration method,the invention also can rapidly stimulate the external stimuli,and easy to recover.In order to further explore the difference between the metastable assembly and typical magnetic assembly,? designed two kinds of assembly oriented,which are assembled polystyrene with high volume fraction and low volume fraction and the magnetic fluid system.Through the microscope,behavior of assembly and assembly and solution recovery,it can be further confirmed that the former is the metastable state assembly and the latter is the typical magnetic assembly,and their behavior can be different by different stress response.