Tuning the Solubility Parameters of Carbon Nanotubes by Means of Their Adducts with Janus Pyrrole Compounds

Abstract

The solubility parameters of multiwalled carbon nanotubes (CNTs) was tuned via their chemical modification with pyrrole compounds (PyCs), by means of a simple and sustainable methodology. PyCs were synthesized with high atom efficiency through the Paal–Knorr reaction of primary amines with 2,5-hexanedione, in the absence of solvents and catalysts. Methylamine, 1-dodecylamine, 2-amino-1,3-propanediol, and 3-(triethoxysilyl)propan-1-amine were selected. PyCs are characterized by two moieties, the pyrrole ring and the substituent of the nitrogen atom, and can be considered as Janus molecules. The functionalization of CNTs occurred with a high yield by simply heating CNTs and PyC. The whole reaction pathway did not produce any waste and was characterized by a carbon efficiency up to almost 100%. Thanks to the variety of PyC chemical structures, the CNT solubility parameter was modified in a pretty broad range of values, in the expected direction. Stable CNT dispersions were prepared in different solvents. From the aqueous dispersion, coating layers were prepared with high electrical conductivity, larger with respect to a top commercial product. The “pyrrole methodology” reported here is based on one reaction and allows almost infinite variations of the CNT solubility parameter, thus promoting their compatibility with target matrices and allowing the preparation of nanocomposite materials with improved properties. This work thus paves the way for a highly efficient exploitation of CNTs.

Bionanocomposites based on a covalent network of chitosan and edge functionalized graphene layers

“…Moving from these observations, the solubility parameters were estimated, by adopting the method described in the literature. 43,51,53,54 Solubility spheres, which enclose the good solvents and exclude the bad ones, were generated.…”

“…The detailed procedure for the determination of the Hansen solubility parameters have been reported as Supplementary material (S2). 51 Characterization of G-CHO/chitosan nanocomposites. UV-Vis spectroscopy -G-CHO and G-CHO/CS suspensions (3 mL) were placed, by using a Pasteur pipette, in quartz cuvettes of 1 cm optical path (volume 1 or 3 mL) and analyzed by a spectrophotometer Hewlett Packard 8452A Diode Array Spectrophotometer.…”

“…The detailed procedure for the determination of the Hansen solubility parameters have been reported as Supplementary material (S2). 51…”

Facile Edge Functionalization of Graphene Layers with a Biosourced 2-Pyrone

“…The Hansen 55 and Hildebrand 64 solubility parameters of HSAG and HASG-Pyr-COOEt have been evaluated, elaborating the Hansen solubility sphere and have been summarized elsewhere by some of the authors. 56 In brief, by the Hansen method, it is possible to estimate the solubility parameters (HSP) based on supramolecular interactions between a solvent and a solute: dispersion forces (δ D ), polar forces (δ P ), and hydrogen bonding (δ H ). The Hildebrand total (δ T ) solubility parameter is obtained by the sum of the squares of the HSP.…”

Curing, thermal, tensile and flammability characteristics of sepiolite/ethylene propylene diene monomer rubber composites with glut palmitate salt and silane coupling agents

“…[27] In other studies, SEP was treated with three ionic liquids using the ion-exchange method [28] and SEP was modified with the acid treatment (HCl). [29,30] The alkali treatment was used to modify SEP with rubber in another study. [31] Also, SEP was organically modified using ammonium cations (CTAB and TTAB) to compare with the mechanical properties of the unmodified SEP. [32] Besides, grafting silane is the most commonly used method for modifying SEP, as reported in a few studies.…”