References of "Dettlaff-Weglikowska, Ursula"
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See detailTowards efficient dispersion of carbon nanotubes in thermotropic liquid crystals
Schymura, Stefan; Kühnast, Martin; Lutz, Vanessa et al

in Advanced Functional Materials (2010), 20(19), 3350-3357

Motivated by numerous recent reports indicating attractive properties of composite materials of carbon nanotubes (CNTs) and liquid crystals (LCs) and a lack of research aimed at optimizing such composites ... [more ▼]

Motivated by numerous recent reports indicating attractive properties of composite materials of carbon nanotubes (CNTs) and liquid crystals (LCs) and a lack of research aimed at optimizing such composites, the process of dispersing CNTs in thermotropic LCs is systematically studied. LC hosts can perform comparably or even better than the best known organic solvents for CNTs such as N-methyl pyrrolidone (NMP), provided that the dispersion process and choice of LC material are optimized. The chemical structure of the molecules in the LC is very important; variations in core as well as in terminal alkyl chain influence the result. Several observations moreover indicate that the anisotropic nematic phase, aligning the nanotubes in the matrix, per se stabilizes the dispersion compared to a host that is isotropic and thus yields random tube orientation. The chemical and physical phenomena governing the preparation of the dispersion and its stability are identified, taking into account enthalpic, entropic, as well as kinetic factors. This allows a guideline on how to best design and prepare CNT–LC composites to be sketched, following which tailored development of new LCs may take the advanced functional material that CNT–LC composites comprise to the stage of commercial application. [less ▲]

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See detailNanotube alignment using lyotropic liquid crystals
Lagerwall, Jan UL; Scalia, G.; Haluska, Miroslav et al

in Advanced Materials (2007), 19(3), 359-364

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See detailEffect of phenyl rings in liquid crystal molecules on swcnts studied by raman spectroscopy
Scalia, G.; Lagerwall, Jan UL; Haluska, Miroslav et al

in Physica Status Solidi B. Basic Research (2006), 243(13), 3238-3241

Carbon nanotubes can be aligned by dispersing them in a liquid crystalline matrix. To control and opti- mize the obtained alignment it is important to understand the interactions between the molecules of ... [more ▼]

Carbon nanotubes can be aligned by dispersing them in a liquid crystalline matrix. To control and opti- mize the obtained alignment it is important to understand the interactions between the molecules of the liquid crystal host phase and the carbon nanotubes. To this end we have carried out resonant Raman spec- troscopy investigations of dispersions of single-wall carbon nanotubes (SWCNTs) in a liquid crystal com- pound comprising molecules with a biphenyl rigid core structure. We detect a distinct wavenumber shift of the radial breathing modes, confirming that the carbon nanotubes interact with the surrounding liquid crystal molecules, most likely through aromatic interactions (π-stacking). The interactions between liquid crystal host and nanotube guests are also evident from a polarizing microscopy study of the liquid crys- tal – isotropic phase transition in the proximity of bundles of nanotubes. The ordered liquid crystal phase is stable up to higher temperatures around the bundles than in areas without visible signs of CNTs. Con- versely, the transition from the disordered isotropic phase to the liquid crystal phase on cooling always nucleates at the carbon nanotube bundles. [less ▲]

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See detailSimultaneous alignment and dispersion of carbon nanotubes with lyotropic liquid crystals
Lagerwall, Jan UL; Scalia, G.; Haluska, Miroslav et al

in Physica Status Solidi B. Basic Research (2006), 243(13), 3046-3049

We demonstrate that single-wall carbon nanotubes (SWCNTs) can be macroscopically aligned by means of templating in a lyotropic nematic liquid crystal (LC), a self-assembling anisotropic fluid with orienta ... [more ▼]

We demonstrate that single-wall carbon nanotubes (SWCNTs) can be macroscopically aligned by means of templating in a lyotropic nematic liquid crystal (LC), a self-assembling anisotropic fluid with orienta- tional but no translational order. The CNTs spontaneously adopt the alignment of the host, as we verify by means of resonant Raman spectroscopy. The aqueous LC host, based on the surfactant SDS, simultane- ously keeps the nanotubes well dispersed over time scales of months or longer. The LC can be loaded with CNTs to almost the same extent as the standard isotropic 1% surfactant solutions normally used for dispersing CNTs without any optically visible bundling occurring. [less ▲]

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