Modeling of the Halloysite Spiral Nanotube

Abstract

A computational SCC-DFTB investigation dealing with the structure of hydrated and anhydrous halloysite nanotubes with a spiral geometry is reported. The peculiar characteristics of these systems are described in terms of tetrahedral and octahedral distortions, of hydrogen bonds geometries involving water molecules and the surfaces in the hydrated nanotube, and of the interlayer interactions in the anhydrous one. When the properties of the spiral nanotube are compared with those of the kaolinite sheet, a certain degree of intrinsic disorder in the halloysite systems is revealed, due to the intrinsic nature of the spiral folding. This is particularly evident in the hydrogen bonds network occurring in the hydrated nanotube

Covalently modified halloysite clay nanotubes: synthesis, properties, biological and medical applications

“…A first attempt to model halloysite nanotubes was made by Guimaraes et al, 14 more recently, Ferrante et al reported, 15 for the first time, the molecular ab initio calculations on spiral halloysite nanotubes, both in the hydrated form and in the anhydrous form. The authors found that, in the hydrated HNT form, the water molecules should have a major effect on stabilizing the spiral structure compared to the unrolled one.…”

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

“…Halloysite nanotubes are composed of a silicon oxygen tetrahedron and alumina oxygen octahedrons forming a kaolinite-like sheet that rolls up, giving the clay its own hollow tubular structure ( Figure 1a) [11,12]. Since the lumen and the external surface are chemically different, they are positive and negative in water, respectively, in the 2-8 pH range [13].…”

Molecular Modeling of Adsorption of 5-Aminosalicylic Acid in the Halloysite Nanotube

“…Although the internal diameter of a natural halloysite nanotube is around 15-50 nm, our model can be a good scenario to reproduce the interactions of the adsorption process at the molecular level. diameter [23][24][25]. Halloysite nanotubes are common excipients in pharmaceutical products and can modify drug bioavailability.…”

“…Halloysite, Al 2 Si 2 O 5 (OH) 4 ·nH 2 O, is a multilayer nanotubular clay mineral resulting from the wrapping of 1:1 layers of kaolinite with dimensions of 500-1000 nm in length and 15-100 nm in inner diameter [23][24][25]. Halloysite nanotubes are common excipients in pharmaceutical products and can modify drug bioavailability.…”