Incorporation of Carbon Nanotubes into a Lyotropic Liquid Crystal by Phase Separation in the Presence of a Hydrophilic Polymer

Abstract

Single-walled carbon nanotubes (SWNTs) were incorporated into a lyotropic liquid crystal (LLC) matrix formed by n-dodecyl octaoxyethene monoether (C(12)E(6)) at room temperature through spontaneous phase separation induced by nonionic hydrophilic polymer poly(ethylene glycol) (PEG). The quality of SWNTs/LLC composite was evaluated by polarized microscopy observations and small-angle X-ray scattering (SAXS) measurements. The results obtained clearly indicated that SWNTs have been successfully incorporated into the LLC matrix up to a considerable high content without destroying the LLC matrix, although interesting changes of the LLC matrix were also induced by SWNTs incorporation. By varying the ratio of PEG to C(12)E(6), the type of LLC matrix can be controlled from hexagonal phase to lamellar phase. Temperature was found to have a significant influence on the quality of SWNTs/LLC composite, and tube aggregation can be induced at higher temperature. When SWNTs were changed to multiwalled carbon nanotubes (MWNTs), they became difficult to be incorporated into LLC matrix because of an increase in the average tube diameter.

Thermo-responsive graphene dispersions by liquid phase exfoliation of graphite aided by an alkylated Percec monodendron

“…4), the homogeneous dispersion became to precipitate. This unstability of G-dl can be ascribed to the desorption of 1 from the graphene lattice, which is reminiscent of the phenomenon observed in surfactant-wrapped CNTs [24,25]. In fact, the influence of temperature on the adsorption-desorption of 1 on the graphene surface can be already seen during the exfoliation of graphite.…”

“…Previously, we have reported that the dispersion state of surfactant-wrapped CNTs can be controlled by the variation of temperature [24,25]. Considering the structural similarity between graphene and CNTs, such rule might be also applied in graphene dispersions.…”

Lyotropic Liquid Crystals Incorporated with Different Kinds of Carbon Nanomaterials or Biomolecules

“…The heating process may also induce the desorption of the amphiphilic molecules from the surface of the CNTs, leading to the aggregation of the CNTs [26]. To overcome these problems, Xin and coworkers developed a nondestructive strategy to incorporate SWNTs into LLCs utilizing the spontaneous phase separation between a nonionic surfactant (n-dodecyl hexaoxyethylene glycol monoether, C 12 E 6 ) and a hydrophilic polymer (poly(ethyiene glycol), (PEG)) [27]. After phase separation, an upper phase contains hexagonal LLCs incorporated by SWNTs together with a bottom isotropic phase consisting of PEG (Figure 1A and B).…”

Carbon Nanotubes in Liquid Crystals: Fundamental Properties and Applications

“…For effective incorporation of SWCNTs into LLCs the method of phase separation in the presence of water soluble polymers was proposed [252][253][254]. The method consist of the initial incorporation of CNTs into the LLC phase formed by an anionic surfactant SDS or a cationic surfactant CTAB [252].…”

“…In the similar work the CNTs were initially incorporated in LLC formed by C 12 E 6 . Then the spontaneous phase separation was induced by addition of nonionic hydrophilic polymer PEG [253]. The hexagonal and lamellar phases were observed in dependence of the ratio of PEG to C 12 E 6 .…”