Search

Research on hexagonal boron nitride (hBN) 2-dimensional nanostructures has gained traction due to their unique chemical, thermal, and electronic properties. However, to make use of these exceptional properties and fabricate macroscopic materials, hBN often needs to be exfoliated and dispersed in a solvent. In this review, we provide an overview of the many different methods that have been used for dispersing hBN. The approaches that will be covered in this review include solvents, covalent functionalization, acids and bases, surfactants and polymers, biomolecules, intercalating agents, and thermal expansion. The properties of the exfoliated sheets obtained and the dispersions are discussed, and an overview of the work in the field throughout the years is provided.

Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs. These studies show that the photoluminescence of both, that is, of the ruthenium complexes and of SWCNTs, are quenched when they interact with each other. Pump-probe transient absorption experiments were performed to shed light onto the nature of the photoluminescence quenching, showing carbon nanotube-based bands with picosecond lifetimes, but no new bands which could be unambigously assigned to photoinduced charge transfer process. Thus, from the spectroscopic data, we conclude that quenching of the photoluminescence of the ruthenium complexes is due to energy transfer to proximal SWCNTs.

In this review, we systematically describe the state-of-knowledge in the area of carbon nanotubides (CNTDs). CNTDs can be used for achieving highly concentrated dispersions of SWCNTs and can also be used as an important intermediate for covalent chemical modification. In recent years, researchers have used SWCNTDs as starting materials for the functionalization of SWCNTs with functionalities such as alkyl chains, carboxylic acids, sulfide, amino, hydroxyl, silyl, bromide, ethers, ketones and polymers. Also, we discussed the observed selectivity on the covalent functionalization towards certain classes of CNTs. Finally, we describe the use of SWCNTDs in the manufacture of fibers, films and other functional materials.