(287f) Preparation, Assembly and Application of Surface Anisotropic (Janus) Particles

The chemical and physical properties of materials rely on their composition, shape and size.¹ Micro and sub-micron scale composites containing nano-structure such as core-shell particles have received attention because of their special properties attributed to both their size and their variation in composition.² Anisotropic composites, e.g., core-half shell particles, are of interest because of their directional property in addition to their size and composition.³ Partial surface decoration of symmetric particles is one of the approaches used to fabricate Janus particles employing either templating or vapor deposition methods. The vapor deposition techniques are widely applied taking advantage of their line-of-sight directional deposition, however, at the cost of high temperature, vacuum, and expensive equipment requirements.

In this talk, a liquid phase templating process, electroless deposition (ELD), is introduced because of its moderate conditions, material flexibility, and low cost. A solid template preparation procedure and the asymmetric deposition of various metals such as silver, gold, and platinum on microspheres are discussed.⁴ We will show that ELD modified spheres posses a much rougher surface compared to spheres modified using vapor deposition, effecting the self- and directed assembly of these Janus particles. Preliminary results on the combination of both vapor and electroless deposition resulting in dual-patch Janus microspheres will be reported. In addition, Janus particles are loaded into an electroactive polymer and their effect on the elctromechanical deformation of the polymer actuator will be discussed as one application of Janus particles.⁵

1. N. L. Rosi, C. A. Mirkin, Chem. Rev. 2005, 105, 1547-1562

2. A. S. Edelstein, R. C. Cammarata, Nanomaterials: Synthesis, Properties and Applications, Institute of Physics Publishing, Bristol an Philadelphia, 1996

3. A. Perro, S. Reculusa, S. Ravaine, E. Bourgeat-Lami and E. Duguet, J. Mater. Chem., 2005, 15, 3745?3760

4. J.-Q. Cui and I. Kretzschmar, Langmuir, 2006, 22, 8281-8284

5. J.-Q. Cui, A. Maliakal and I. Kretzschmar, ?TiO2 nanoparticles/poly(acrylate) elastomer composite films as actuators?, 2008 MRS Spring Meeting, March 2008, San Francisco (Oral presentation J8.4)