Translated Abstract
Electrophoretic microcapsule display technology solves the problem of aggregation and horizontal migration of colloidal particles, and has great potential to be used in military camouflage, color display, civil coating, and other fields. However, it is extremely limited in the process of realizing full-color dynamic display due to its drawbacks such as single color rendering and slow response. The magnetic-responsive colloidal photonic crystals prepared by the author＇s group are a kind of crystalline colloidal arrays with obvious photonic bandgap characteristics formed by the magnetic colloidal particles in solution under the applied magnetic field. The structural parameters of the crystalline colloidal array can be tuned by changing the strength of the magnetic field so that they can display structural colors in the entire visible light region. These materials have potential to be new types of color display material with precise positioning control, flexible and diverse features. However the dependence on the liquid environment makes the photonic ink greatly restricted in practical application. In this paper, the photonic microcapsules with dynamically tunable structure color were successfully obtained by encapsulating the magnetically-responsive photonic crystals in the microcapsules. Then the structure, magnetic properties and optical properties of the microcapsules have been studied thoroughly. The main research contents are as follows:
1. Monodisperse superparamagnetic Fe3O4 colloidal particles with an average particle size of about 200 nm and a saturation magnetization of 73 emu/g were prepared by a hydrothermal method. They can be well dispersed in water and displayed bright structural color under the applied magnetic field. Then, the particles were treated by surface silanization through the modified Stöber method which improves the stability of the colloidal particles in the solution and the structural color further. Then through further hydrophobic modification of the silanized Fe3O4 colloidal particles, realized its stable dispersion in tetrachloroethylene, n-octane and and the tunable structural color characteristic under the applied magnetic field can be maintained.
2. The photonic microcapsule with magnetic response with about 150um was successfully prepared by using the complex coagulation method, with gelatin/arabica gum as the cyst wall and hydrophobic Fe3O4 colloidal solution as the capsule core. The colloidal particles in the microcapsules can form crystalline colloidal arrangement under the external magnetic field and show quick response to the magnetic field. The structural color of the microcapsule can be tuned by changing of the magnetic field strength. In addition, Fe3O4 colloidal particles can maintain their tunability for a long time due to the special structure of microcapsules.
3. Magnetically-responsive photonic microcapsules with an average diameter of about 300 μm were successfully prepared by encapsulating the microdroplets of Fe3O4 colloidal solution light-curable transparent ETPTA gels. Compared with the traditional emulsification method, as-prepared microcapsules have uniform size, uniform shell thickness, good dispersibility, and can self-assemble into an ordered structure. Moreover, the size of its core and shell can be controlled, which makes them have great opportunity to become more ideal tunable photonic materials.
These photonic crystal microcapsules with dynamic full-color display ability have great potential to be applied in civil painting, printing, and flexible color display.
Translated Keyword
[Collidal photonics crystals, Magnetoelectric-response, Microcapsule, Optical property, Structural color]
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