Halloysite nanotube with fluorinated lumen: Non-foaming nanocontainer for storage and controlled release of oxygen in aqueous media

Abstract

Halloysite clay nanotubes were selectivity modified by adsorbing perfluoroalkylated anionic surfactants at the inner surface. The modified nanotubes formed kinetically stable dispersions due to the enhanced electrostatic repulsions exercised between the particles. We proved that the modified nanotubes can be used as non-foaming oxygen nanocontainers in aqueous media. The gas release from supersaturated dispersions can be controlled by external stimuli and system composition. In conclusion, we managed to put forward an easy strategy to develop smart materials from natural nanoclays, which can endow important applications like the storage and delivery of gas.

A synergic nanoantioxidant based on covalently modified halloysite–trolox nanotubes with intra-lumen loaded quercetin

“…In acetonitrile, quercetin bound to sites L 1 and L 2 is rapidly and almost completely released, while that bound to the high affinity site L 3 is negligibly released. Halloysite has specific surface area of 65 m 2 g À1 ; 11 taking the average length of 770 nm and an external diameter of 73 nm, 51 considering that its cavity accounts for about 10% its volume 51 and quercetin has a molecular surface of about 70 Å 2 , it can be calculated that a monolayer of quercetin adsorbed in the inner lumen would account for about 1.5 wt%, in line with previous calculations for the load of monolayer surfactants. 51,52 This calculated value, which would correspond to 63% of the quercetin loading into HNTs, is equivalent to the value of 61% obtained form our fittings for the binding site L 3 .…”

“…Halloysite has specific surface area of 65 m 2 g À1 ; 11 taking the average length of 770 nm and an external diameter of 73 nm, 51 considering that its cavity accounts for about 10% its volume 51 and quercetin has a molecular surface of about 70 Å 2 , it can be calculated that a monolayer of quercetin adsorbed in the inner lumen would account for about 1.5 wt%, in line with previous calculations for the load of monolayer surfactants. 51,52 This calculated value, which would correspond to 63% of the quercetin loading into HNTs, is equivalent to the value of 61% obtained form our fittings for the binding site L 3 . We suggest that the high affinity site corresponds to the surface of the inner lumen, which is expected to bind the mildly acidic quercetin through strong H-bonding and Coulombic interactions, from which it is slowly released following solid-liquid reversible adsorption-desorption kinetics.…”

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

“…More interestingly, it was shown that the concentration effect was negligible and that the hybrid materials did not associate; however, nanotubes diffuse as single particles [61].…”

“…It was also found that perfluoroalkylated surfactants, when adsorbed at the internal surface, created stable suspensions, and these systems can be exploited as nanocontainers of non-foaming oxygen in aqueous media for gas delivery by external stimuli [61].…”

Smart Nanocontainers: Preparation, Loading/Release Processes and Applications

“…Regarding the nanostructures, nanocontainer can be divided into 3 main groups including: i) nanoparticles based nanomaterials (three-dimensional nanostructure) [1][2][3][4], ii) nanotubes (one dimension) [5][6][7][8], and iii) nanolayers based nanomaterials (two-dimensional nanostructure) [9][10][11]. Similarly, in terms of synthetic materials, nanocontainers consist of organic or inorganic scaffolds in which the encapsulation of active substances has been carried out.…”