Pairs of entangled colloids |
  FIGURE 1: Assembling entangled colloidal pairs by thermal quench using light.  MOVIE: By quenching a pair of quadrupolar particles from the isotropic melt into the nematic phase we can get again two single quadrupoles or an entangled pair. | We have shown that colloidal dimmers bound by topological defect loops can be created by locally thermally quenching a thin layer of the nematic liquid crystal around selected colloidal pair (Movie 1). Figure 1 summarizes what happens, when a pair of colloidal particles is quenched from the isotropic melt into the nematic phase using local heating by an intense laser light. First, a pair of separated quadrupolar colloidal particles are positioned close to each other, and then their liquid crystalline surrounding is molten into the isotropic phase by intense laser light. Immediately after switching-off the light, a dense tangle of defect loops is created (1a and 1b), which in the course of time annihilate and "dilute". After few seconds entangled states "figure of eight" and "figure of omega" can be formed (1c and 1d). The figure of omega is unstable and can transforms into the "entangled hyperbolic defect" (1e). Coloured figures represent calculated entangled structures, which were observed in the experiment. RAVNIK, Miha, ŠKARABOT, Miha, ŽUMER, Slobodan, TKALEC, Uroš, POBERAJ, Igor, BABIČ, Dušan, OSTERMAN, Natan, MUŠEVIČ, Igor. Entangled nematic colloidal dimers and wires. Phys. rev. lett., 2007, vol. 99, no. 24, 247801-1-247801-4. |
