Surface studies of halloysite nanotubes by XPS and ToF‐SIMS

Abstract

This report provides detailed experimental results of thermal and surface characterization on untreated and surface-treated halloysite nanotubes (HNTs) obtained from two geographic areas. Surface characterization techniques, including XPS and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used. ToF-SIMS surface analysis experiments were performed with both atomic and cluster ion beams. Higher ion yields and more high-mass ions were obtained with the cluster ion beams. Static ToF-SIMS spectra were analyzed with principal component analysis (PCA). Morphological diversities were observed in the samples although they mainly contained tubular structures. Thermogravimetric data indicated that aqueous hydrogen peroxide solution could remove inorganic salt impurities, such as alkali metal salts. The amount of grafting of benzalkonium chloride of HNT surface was determined by thermogravimetic analysis. PCA of ToF-SIMS spectra could distinguish the samples mined from different geographical locations as well as among surface-treated and untreated samples.

Synthesis of pH-sensitive poly (N,N-dimethylaminoethyl methacrylate)-grafted halloysite nanotubes for adsorption and controlled release of DPH and DS drugs

“…According to the results of Table 2, the ratio of Si and Al in both of nanotubes, HNT and HNTBr, is greater than unity, which shows that the proportion of silicate is larger than the aluminate groups in the outer surface of halloysite [35]. Also, this value is larger in the case of HNT-Br which assigned to the presence of APTES groups on its surface.…”

High-impact polystyrene/halloysite nanocomposites prepared by emulsion polymerization using sodium dodecyl sulfate as surfactant

“…Depending on different mining geographic areas, the lengths and diameters of the nanotubes can vary significantly [17]. SDS, which is an anionic surfactant, is a good dispersing agent for HNTs in aqueous solution [18]. With the addition of SDS, the HNT aqueous suspension was very uniform and stable and could last for a few days.…”

Halloysite for Controllable Loading and Release

“…The first detailed study on the functionalisation of halloysite walls by cationic and anionic surfactants was performed by Ng et al (2011) on the other hand, showed significant levels of carbon and nitrogen on the external surface (Ng et al, 2011). The internal lumen of halloysite was hydrophobised with anionic perfluoro C5-C7 alkyl surfactants (Cavallaro et al, 2014).…”