Clay nanotubes/ionic surfactant: Smart hybrid nanomaterials for the solubilization of hydrophobic compounds in aqueous media

The functionalization of nanoclays is a relevant strategy to tune their properties in aqueous media.1,2 Among this kind of nanomaterials, natural halloysite nanotubes (HNTs) are very promising.3,4 The HNTs surface is composed of Si−O−Si groups in the external part, whereas it consists of a gibbsite-like array of Al-OH groups in the lumen. This different chemical structure confers, in water, the negative and positive charge at the outer and inner surfaces, respectively.3,5 As concerns the HNTs characteristic sizes, they are quite polydisperse with a length of ca. 1 µm, the outer diameter is 30-50 nm while the inner cavity is in the range 1-30 nm.3 Recently it has been demonstrated that the inner cavity size can be changed in a controlled way by means of selective ...