Magnetic Field-Induced Optical Properties And Application Of Magnetorheological Elastomer Films Based On Polydimethylsiloxane

Magnetorheological elastomer(MRE) is a class of intelligent material with wide application prospect. Typically it is prepared by distributing the micron sized magnetic particles in nonmagnetic elastic polymer. By applying external magnetic field, a chain structure of the magnetic particles formed in the matrix along the magnetic field, which shows the anisotropy of the material properties. At present, the research of MREs focuses on the field of vibration control, and little effort is devoted to the field of micro and optics. To expand the research of MREs to the field of micro and optics,MRE films based on polydimethylsiloxane (PDMS) were prepared and the influence of magnetic particle content, microstructure, magnetic field on there optical transmittance was studied. The preparation method and relevant process parameters of MRE films were determined. The measurement of film optical transmittance was completed, and the methods of film optical transmittance measurement were determined.Through the study found that the optical transmittance of anisotropic PDMS-Fe3O4 MRE film is higher than that of isotropic film, when particle content is the same and no external magnetic field. In particle content is 5wt%, the difference of optical transmittance between anisotropic film and isotropic film reached the maximum, anisotropic film higher 16.66%. The optical transmittance has increased significantly when applied external magnetic field, it increases to maximum when particle content is lwt%, isotropic film increased 17.04%, anisotropic film increased 23.01%.The optical transmittance increased by magnetic field-induced of anisotropic films is always higher than that of isotropic films, in the same particle content. For PDMS-Fe MRE film, when particle content is 7wt%and no external magnetic field, the difference of optical transmittance between anisotropic film and isotropic film reached the maximum anisotropic film higher 5.39%. The optical transmittance has decreased when applied external magnetic field, anisotropic film in particle content is 7wt% decreased most, reduce 4.86%, the isotropic film in particle content 13wt%decreased most, reduce 3.23%. The optical transmittance decreased by magnetic field-induced of isotropic film is always higher than the anisotropic film, in the same particle content. According to the above measurement results, access to literature, analysis model to analyze the reasons for the light transmittance changing caused by the micro-structure and external magnetic field. Different degrees of scattering light different microstructures, resulting in a difference in the light transmittance of the film. After applying an external magnetic field, different film microstructure will produce different deformation, resulting in a difference in the light transmittance of the film after loading the magnetic field.Through theoretical analysis, we find that the refractive index of MRE films based on PDMS higher than that of pure PDMS. The refractive index of film increased with the increase of content of magnetic particles.MRE film based on PDMS will be in a state of stress by applied an external magnetic field, the refraction index of PDMS will change in a state of stress, this means that the refractive index of MRE films based on PDMS will change by applied an external magnetic field.Based on the above research results, magnetic field-induced micro lens array of the MRE films based on PDMS was designed.