Preparation of a novel (polymer/inorganic nanofiber) composite through surface modification of natural aluminosilicate nanofiber

Imogolite is one of the aluminosilicates with a chemical formula of Al(2)O(3)SiO(2) (H(2)O)(n), consisting of hollow nanotubes with an external diameter of about 2.5 nm and a length from several hundred nanometers to a micrometer. Atomic force microscopic (AFM) observation revealed that the imogolite molecules form a fibrous network at pH=3.0. Since the outer surface of imogolite consists of the Al-OH group, a strong interaction can be expected between the Al-OH and the -PO(OH)(2) groups. Octadecylphosphonic acid (OPA) was chosen as a model amphiphilic molecule, and it chemisorbed onto the surface of imogolite. Surface coverage of imogolite with OPA was confirmed by infrared spectroscopy, thermogravimetric analysis, and adhesion force measurement by (AFM). The OPA-chemisorbed imogolite was dispersed in hexane whereas it forms precipitates in water. Since imogolite engages in a specific interaction with -PO(OH)(2) groups, it is expected that imogolite can be molecularly dispersed in -PO(OH)(2) group-modified poly(vinyl alcohol) (PVA). Temperature dependence of dynamic viscoelasticity exhibited a higher temperature shift of the alpha a -absorption of the matrix phosphorylated PVA for the (imogolite/phosphorylated PVA) hybrid compared with that for phosphorylated PVA.