Colloids with uniform, well-controlled Bond-Angles

Colloids can just like atoms bind to form colloidal molecules

Tunable patchiness

Cross-linked latex particles with liquid protrusions were found to self-assemble into a wide variety of colloidal molecules by merging of liquid protrusions. Driven by surface energy the system strives to minimize the total interface between the protrusions and the water phase by fusion of the liquid protrusions. The obtained colloidal particles have a well controlled topology with unique configurations for each number of seed particles at given synthesis conditions. The wetting angle and the size of the liquid protrusions determine which colloidal molecules are formed upon coalescence (Kraft et al. JACS 2009). When the seed particles are restricted inside the fused protrusions, they form clusters that minimize the second moment of the mass distribution.

Large assemblies containing 100-1000 seed particles were found up to a size of 14μm in diameter. The seed particles at the oil-water interface show strain relief by scar formation.

See also “A Colloidal Erector Set, Science

Colloidal Molecules with a controlled bond angle

With this technique, we can also synthesize colloids with a well-controlled a bond angle (Figure 4), such as colloidal water and ammonia. This is achieved by increasing the swelling ratio to the point where the seed particles can freely move inside the fused liquid protrusions. Polymerization induces clustering, which leads to well controlled bond angles that can be "made-to-order" by adjusting the swelling ratio (Kraft et al. Soft Matter 2009).

Polymer colloids with controllable number of protrusions

By tuning the synthesis conditions, we can control the number of protrusions appearing on the surface of highly cross-linked polymer spheres. High particle yields > 90% are achievable. We employed the technique for polyNIPAM, polystyrene, and magnetite filled polyNIPAM spheres. Partial roughness is achieved through adsorption of secondary particles, or wrinkling of the seed particle surface. (Kraft et al., JPCB (2011))

Rotating a 3 dimensional model confirms that all colloidal particles with a particular number of seed spheres have uniform shape.

Colloidal Molecules
Pickering EmulsionsEquilibrium_Emulsions.html
Colloidal MicellesColloidal_Micelles.html
Zipper model for TMVKinetic_Zipper_Model.html

Our particles were featured on the Cover of the special issue of JPCB

Colloidal Molecules

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