Direct Nanorod Assembly Using Block Copolymer-Based Supramolecules

Abstract

Developing routes to control the organization of one-dimensional nanomaterials, such as nanorods, with high precision is critical to generate functional materials since the collective properties depend on their spatial arrangements, interparticle ordering, and macroscopic alignment. We have systematically investigated the coassemblies of nanorods and block copolymer (BCP)-based supramolecules and showed that the energetic contributions from nanorod ligand-polymer interactions, polymer chain deformation, and rod-rod interactions are comparable and can be tailored to disperse nanorods with control over inter-rod ordering and the alignment of nanorods within BCP microdomains. By varying the supramolecular morphology and chemical nature of the nanorods, two highly sought-after morphologies, that is, nanoscopic networks of nanorods and nanorod arrays parallel to cylindrical BCP microdomains can be obtained. The supramolecular approach can be applied to achieve morphological control in nanorod-containing nanocomposites toward fabrication of optical and electronic nanodevices.

End-to-End Alignment of Nanorods in Thin Films

“…The last group of terms encompasses additional energetic contributions due to the anisotropy of the NRs and applies to NR nanocomposites in both bulk form and in thin films. 38 The particle−particle interaction, ΔG p−p , favors side-toside NR assembly due to the dipole−dipole attraction and the depletion attraction. 8 The orientational entropy of the NRs, ΔS orient , accounts for the entropy originating from the anisotropic shape of NR.…”

“…For NR nanocomposites, ΔS con depends on the NR orientation and can be modulated by varying the morphology of supramolecular framework. 38 The geometric confinement from the surpamolecular framework not only controls NR location but also NR orientation. As shown in bulk, 38 the NR assembly upon blending with supramolecule mainly reflects the energetic competition between ΔG p-p and ΔS con .…”

Binary colloidal structures assembled through Ising interactions

“…Multi-component colloidal systems [26][27][28][29][30][31][32][33][34][35] (that is, 'colloidal alloys') as well as systems of particles with non-trivial internal structure, such as Janus particles [36][37][38][39] and particles with shape anisotropy [40][41][42] , are currently being explored due to their ability to tailor the particle interactions and enable the assembly of diverse crystalline structures. Current methods for assembling ordered structures with two or three particle types include kinetic techniques based on controlled drying [26][27][28][29][30][31] and thermodynamic techniques [32][33][34][35]43,44 that rely on spontaneous assembly into minimum free-energy configurations.…”

Orientational ordering of nanorods in diblock copolymers

“…At the same time, the polystyrene functionalized nano-rods are orientationally ordered in the hexagonal phase of the same block copolymer with their long axes perpendicular to the cylinders [25,26]. In contrast, the alkyl phosphonic acid capped nano-rods are ordered parallel to the cylinders [27]. In block copolymers, each block is isotropic in the bulk but there exists also a regular structure of interfaces between the blocks which determines the macroscopic anisotropy of the system.…”