We prepared biocompatible hybrid halloysite nanotubes (HNTs) with a tunable hydrophobic/hydrophilic interface. The HNTs inner cavity selective surface modification generates inorganic micelles with a hydrophobic pocket and a cylindrical symmetry. The colloidal stability of surfactant/HNTs materials in water is reviewed showing the strategy and the mechanism to obtain stable dispersions in the low and the high concentration regime. The ability of these non-foaming surfactant in entrapping oils and gas is highlighted. The selective modification of the HNTs external surface with cationic surfactants endows to generate tubular nanostructures with an hydrophobic shell and an hydrophilic cavity. To this aim alkyltrimethylammonium bromides have been tested. The influence of the surfactants alkyl chain on the HNTs functionalization degree has been investigated. The dynamic behavior of the surfactant/HNT hybrids in solvents with variable polarity has been correlated to their affinity towards hydrophobic media explored through partition experiments. Water contact angle experiments proved that lengthening the alkyl chain of the surfactant generates the enhancement of surface hydrophobicity. The water-in-oil emulsion is able to solubilize copper sulphate proving the incorporation and the loading of hydrophilic compounds into the HNTs lumen. The prepared inorganic micelles are efficient nanocontainers for the selective entrapment of hydrophilic/hydrophobic active agents. These features may be further exploited for biotechnological, conservation of cultural heritage and pharmaceutical applications.

Halloysite/surfactant hybrids as sustainable nanomaterials

251st National Meeting (2016)

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