University of California

Snu Rdb Foundation

Kwon, Sunghoon

Jianping Ge

Yadong Yin

Sunghoon Kwon

Hyoki Kim

Provided is a method of forming a microsphere having a structural color, which includes providing a composition for generating a structural color including a curable material and magnetic nanoparticles dispersed in the curable material, forming an emulsion by adding the composition for generating a structural color to an immiscible solvent, arranging the magnetic nanoparticles located in the emulsion droplet of the curable material in a one-dimensional chain structure by applying a magnetic field to the emulsion, and fixing the chain structure by curing the emulsion droplet.

Method of forming microsphere having structural color

Monodisperse colloidal nanocrystal clusters of magnetite (FeO) with tunable sizes from about thirty to about three hundred nanometers have been synthesized using a high-temperature hydrolysis process. The colloidal nanocrystal clusters are capped with polyelectrolytes, and highly water soluble. Each cluster is composed of many single magnetite crystallites, thus retaining the superparamagnetic behavior at room temperature. The combination of superparamagnetic property, high magnetization, and high water dispersibility makes the colloidal nanocrystal clusters ideal candidates for various important biomedical applications such as drug delivery and bioseparation. The present invention is further directed to methods for forming colloidal photonic crystals from both aqueous and nonaqueous solutions of the superparamagnetic colloidal nanocrystal clusters with an external magnetic field applied thereto. The diffraction of the photonic crystals can be tuned from near infrared to visible and further ultraviolet spectral region by varying the external magnetic field.

Superparamagnetic colloidal photonic structures

A method of assembling superparamagnetic colloids into ordered structures with magnetically tunable photonic properties in nonpolar solvents by establishing long-range electrostatic repulsive forces using charge control agents. Reverse micelles resulted from the introduction of charge control agents such as AOT molecules can enhance the charge separation on the surfaces of n-octadecyltrimethoxysilane modified FeO@SiOparticles. The significantly improved long-range electrostatic repulsion can counterbalance the magnetically induced attraction and therefore allow ordering of superparamagnetic colloids in nonpolar solvents. This system possesses fast and fully reversible optical response to the external magnetic fields, long-term stability in performance, and good diffraction intensity.

Growing community of inventors

Shanghai, China

Jianping Ge