Formation of Colloids with Optical Traps

Hagay Shpaisman, Bar-Ilan University, Ramat-Gan, Israel
Ifat Jacob, Bar-Ilan University, Ramat-Gan, Israel
Eitan Edri, Bar-Ilan University, Ramat-Gan, Israel
Erel Lasnoy, Bar-Ilan University, Ramat-Gan, Israel
Silvia Piperno, Bar-Ilan University, Ramat-Gan, Israel

During the last decade significant advances in controlling nano objects and polymer/DNA clusters with optical traps have been demonstrated along with the ability to create various phase changes induced by photon pressure. Here we present a novel method were colloidal particles are created when an optical trap is introduced while an emulsion polymerization is taking place. Nucleation seeds, oligomers and micelles are attracted to the trap and (under certain parameters) can coalesce or partly fuse before final polymerization, creating spherical or rod like colloids. Furthermore, we can create organic/inorganic colloidal hybrids if inorganic nanoparticles (NP) are introduced to the organic system undergoing polymerization while optical traps are present. Via a physical absorption process these nanoparticles are incorporated in the growing colloidal particle.

These methods hold great promise for creating on demand tailor made colloidal systems where size, shape and composition could be precisely controlled. The versatility and ease of making various changes to the end product without the need for chemical modifications (as the optical trap influences any material with higher polarizability than the surrounding medium) makes this approach appealing for testing model systems.