The Fabrication And Application Of The Non-spherical Colloidal Particles

Recently, there is a growing interest in synthesis of non-spherical particles such as colloidal dimmers, snowmen and ellipsoids.Because of their unique properties in chemical, physical or optical, such anisotropic colloidal particles may find tremendous potential applications in adva-nced materials, anisotropic photonic crystals, directed self-assembly, and specific binding or bonding. Take the "Janus" particles for example, this kind of "snowman" janus particle can be used as the solid surfactant to stablize the oil/water emulsion. A special photonic crystals with triclinic crystal form can be fabricated by a kind of magnetic ellipsoid. The dumbbell particles can be also used to form photonic crystals with more dense packing ratio of78.62%, bigger than the densest crystalline sphere packing ratio of74.05%. Besides, the lock-and-key specific bonding between the concave particles with single dimple and the spheres particles could used as colloidal molecule model.Generally, there are serveral appro-aches to fabricate anisotropic colloidal particles: confined self-assembly, template assisted synthesis, controlled deformation of spherical particles, microfludics and seeded emulsion polymerization (SEP). For example, the template assisted method can synthesis kinds of colloids with different shapes only if there exist these template particles with the wanted shapes. The non-spherical particles obtained by microfludics method always too big to see a self-assembly, because the particles size is no less than several dozens of micrometers. In a word, there is a emergency need to design the new method to fabricate different shaped colloidal particles.Besides, these techniques often suffer from drawbacks, including (1) sophisticated and highcost procedures such as lithography and micro-fabrication (2) low throughput production, usually particle-by-particle fabrication, and (3) polydispersity in size and/or shape. Although the SEP is a classcial method to synthesize non-spherical colloids high-yieldly, it also has an limitation in the resultant paricles1shapes:only convex shaped colloidal paricles can be fabricated.To explore new preparation method and novel shaped colloids, we had tried two parts of interesting work:(1) useing the dispersion polymerization to fabricate a kind of special mutli-dimple paricles;(2) used as seeded particles, our special mutli-dimple paricles are swelled out to synthsize non-spherical colloids with a spectra of shapes:not only the convex shapes, but also including the non-convex shapes such as bowl-like, hemispherical.Moreover, we successfully extended the potential application of our non-spherical particl-es.Such as the speical mutli-dimple paricle with its unique bonds numbers and sites is a perfect model to explore the recognition and bonding interaction among the spheres. The bowl-like paritcles have a unique self-assembly phenomenon under the applied electric field. After the alternating electric field applied to the bowl-like particles sample, the first anisotropy packing bowls became more order. Because of the mass’s uneven distribution, the bowls can not be polarized isotropic like spheres. The electric dipole moment induced by the electric field make the bowl particles moving with a side-direction way. These side-direction moving particles could aggregated together due to the induced-charge electroosmotic interaction. Our hemispheres may find uses in advanced materials such as solid emulsifier. We demonstrated that this kind bare hemispheres with any further modification can stablize the oil droplets in the water phase. Last but not the least, the egg-shaped composite colloid with its unique opticlal property could be a special block patitcle to fabricate anisotropic photonic crystal.In brief, we introduced two kind of new/or advanced method to design and produce non-spherical colloidal particles. The dispersion polymerization method can be easily developed to scaled production. The multi-dimpled particles used as seeds to fabricate non-spherical particles is a important supplement to the seeded emulsion polymerization. Furthermore, our resultant particles would be perfect model or block particles to find the potential application in advanced functional materials or specific bonding and self-aseembly in the near-future.