Highly Ordered and Highly Aligned Two‐Dimensional Binary Superlattice of a SWNT/Cylindrical‐Micellar System

Abstract

We report a highly ordered intercalated hexagonal binary superlattice of hydrophilically functionalized singlewalled carbon nanotubes (p-SWNTs) and surfactant (C 12 E 5 ) cylindrical micelles. When p-SWNTs (with a diameter slightly larger than that of the C 12 E 5 cylinders) were added to the hexagonally packed C 12 E 5 cylindrical-micellar system, p-SWNTs positioned themselves in such a way that the freevolume entropies for both p-SWNTs and C 12 E 5 cylinders were maximized, thus resulting in the intercalated hexagonal binary superlattice. In this binary superlattice, a hexagonal array of p-SWNTs is embedded in a honeycomb lattice of C 12 E 5 cylinders. The intercalated hexagonal binary superlattice can be highly aligned in one direction by an oscillatory shear field and remains aligned after the shear is removed.One-dimensional (1D) nanoparticles, such as single-walled carbon nanotubes (SWNTs) and metallic, semiconducting, or magnetic nanorods, have unique anisotropic physical properties suitable for a broad range of potential applications, such as optical and electronic devices, [1] sensing [2] and imaging, [3] energy storage, [4] and drug delivery. [5] The self-assembly or guided assembly of 1D nanoparticles into highly ordered superstructures with well-defined symmetry, direction, and density has been of great interest as a route to collectively enhance their physical properties and is the key to the practical realization of various potential applications. Many efforts have been made with this purpose, by the use of various methods, such as solvent evaporation, [6] external fields with patterned substrates, [7] and solution-based assembly based on various interactions. [8] Among these methods, solution-based assembly, which does not require complicated experimental setup or extensive control of evaporation conditions, has been of great interest. [8] For example, solubility control of functional groups, [9] linker-mediated interactions, [10] depletion attraction, [11] dipole-dipole [12] and electrostatic interactions, [13] and the phase behavior of amphiphilic molecules [14] have been utilized to induce the selfassembly of ordered superstructures of 1D nanoparticles, such as Au, PbSe, CdSe, CdSe/CdS nanorods, and SWNTs. However, these techniques are still in their early stages and have been focused on assemblies of single-component 1D nanoparticles.The synthesis of binary or multicomponent superstructures of nanoparticles, which may provide new properties through synergetic coupling between different types of nanoparticles, [15] are of great interest for various potential applications as well as its own scientific merit. Exciting progress has been made in the fabrication of binary spherical-nanoparticle superlattices with various symmetries by using an interplay of entropy and van der Waals, electrostatic, and other interactions. [16] Colloidal mixtures of 1D and spherical nanoparticles have also been reported to self-assemble into three-dimensional superlattices. [17] However, systematic experimental stud...

Molecular Weight-Dependent, Flexible Phase Behaviors of Amphiphilic Block Copolymer/Additive Complexes in Aqueous Solution

“…The peak ratios of and can be indexed to the FCC nanostructure by the Bragg peak index ( Figure 2 a) [ 28 , 29 , 30 ]. Although the sample phases of the P105-5mS complex were visually unchanged, the SAXS signal patterns slowly changed from the FCC nanostructure to the hexagonal phase (peak ratio of ) with an increase in the temperature above 50 °C (light blue arrow in Figure 2 b,c) [ 28 , 31 , 32 ]. The SAXS measurements showed that the interesting phase behavior in the nanoscale region differed from a visual inspection, which revealed only a solid-like gel.…”

Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research

“…For example, the local signature of yielding during large amplitude oscillatory shear has been detected in concentrated oil-in-water nanoemulsions [120]. The shear flow is also an elegant method to orient the sample and deduce high resolution structural information as shown in the case of hexagonal honeycomb and kagome superlattices in surfactant lyotropic hexagonal phase intercalated with single-walled carbon nanotubes [121] and polymer nanorods [122], respectively. Figure 14 illustrates the shear-induced orientation of binary supperlattices with hexagonal honeycomb and kagome structures.…”