Templating

The long-range order and variety of structures possible in liquid crystals are very attractive in many respects, since this can bring nanoscale properties of the species forming the phase to the macroscopic world. However, sometimes the fluid nature of the liquid crystal is not useful in a targeted application, but we want a solid system. In that case we can use the liquid crystal system as a template, which is then polymerized (provided that we add reactive molecules to the system) into a solid state object that retains the order given by the liquid crystal. This is a type of research that we currently engage in extensively, also because it leads to interesting questions well beyond the practically desirable templating effect, in particular in terms of how the polymer chains grow in the liquid crystalline environment and how this growth affects the liquid crystalline order.

Another approach to liquid crystalline templating is to introduce nanoparticles in a liquid crystal host, which organizes the nanoparticles. We have made significant contributions in particular regarding alignment of carbon nanotubes using liquid crystals, within a long-term collaboration with the Dr. Giusy Scalia. Now we are also exploring liquid crystals in which gold nanoparticles are dispersed, within the scope of the project DISGONA, the main activity of our post-doc Martin Urbanski. On the one hand concerning the effect on conductive properties, on the other concerning the ability of the liquid crystalline order to induce controlled aggregation of the nanoparticles. Since the particles are spherical, they can disturb the liquid crystal director field considerably, and if properly prepared we can expect to have nanoparticles that are well dispersed in a liquid crystal material heated to its isotropic state, but if it is cooled to the nematic state, it pushes the particles together into a percolating network within or at the boundaries of the liquid crystal.

Some of our key publications on carbon nanotube templating by liquid crystals are the following:

• Carbon nanotubes in liquid crystals (Review article)
  Jan P. F. Lagerwall, Giusy Scalia
  J. Mater. Chem. 18, 25, pp. 2890-2898 (2008), special issue on ‘Liquid crystals beyond display applications’.
• Filament formation in carbon nanotube-doped lyotropic liquid crystals
  Stefan Schymura, Sarah Dölle, Jun Yamamoto and Jan Lagerwall
  Soft Matter, 7, 6, 2663 - 2667 (2011)
• Tailor-designed polyphilic promotors for stabilizing dispersions of carbon nanotubes in liquid crystals
  Martin Kühnast, Carsten Tschierske and Jan Lagerwall
  Chem. Commun., 46, pp. 6989-6991 (2010)
• Towards Efficient Dispersion of Carbon Nanotubes in Thermotropic Liquid Crystals
  Stefan Schymura, Martin Kühnast, Vanessa Lutz, Stefan Jagiella, Ursula Dettlaff-Weglikowska, Siegmar Roth, Frank Giesselmann, Carsten Tschierske, Giusy Scalia, and Jan Lagerwall
  Adv. Funct. Mater., 20, 19, pp. 3350–3357 (2010)
• Macroscopic-scale carbon nanotube alignment via self-assembly in lyotropic liquid crystals
  S. Schymura, E. Enz, S. Roth, G. Scalia, J.P.F. Lagerwall
  Synth. Met., 159, 21-22, pp. 2177-2179 (2009)
• Spontaneous macroscopic carbon nanotube alignment via colloidal suspension in
  hexagonal columnar lyotropic liquid crystals
  G. Scalia, C. von Bühler, C. Hägele, S. Roth, F. Giesselmann, and J.P.F. Lagerwall
  Soft Matter, 4, 3, pp. 570-576 (2008)
• Nanotube alignment using lyotropic liquid crystals
  Jan P. F. Lagerwall, Giusy Scalia, Miroslav Haluska, Ursula Dettlaff-Weglikowska, Siegmar Roth, Frank Giesselmann
  Adv. Mater. 19, 3, pp. 359-364 (2007)

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