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Smectites are phyllosilicate minerals characterized by a 2 : 1 layer structure in which two tetrahedrally coordinated silica and a length or breadth from a few tens of nm up to 1 mm. Negative charges of the sheet generated by the isomorphous substitution of the layer are counterbalanced by cationic species placed in the galleries. These cations in the gallery can be easily exchanged with organic ions, such as ammonium and phosphonium, to give organically modified materials.
Fig.1 Crystal structure of a dioctahedral smectite nanosheet.
The polymer–clay nanocomposites where the polymer chains are intercalated into the interlayer galleries of clay exhibit useful properties such as mechanical strength, thermal stability, gas barrier and flame retardancy even at very low clay contents as a few mass %. Our research group has been studying the incorporation of polymers, both water soluble and insoluble polymers, into smectites clay. That can lead many useful applications as seen in the following
Some layered clay minerals are known to accommodate various organic substances in their interlayer spaces to form intercalation compounds. Montmorillonite, which is one of typical swelling clay minerals, has been widely used as a host material. In this work, montmorillonite-acrylamide intercalation compounds were prepared by treating sodium montmorillonite with acrylamide aqueous solution. The intercalated acrylamide was polymerized to form montmorillonite-polyacrylamide intercalation compounds. These compounds absorbed more water than raw sodium montmorillonite that can use as water absorbents.
Bionanocomposite materials, a group of organic-inorganic hybrid materials involving naturally occurring polymers and inorganic solids that show at least one dimension at nanometer scale, can exhibit improved structural and functional properties together with biocompatible and biodegradable character associated with the biopolymer. Sacran, an anionic megamolecular polysaccharide extracted from the cyanobacterium. Aphanothece sacran, is an interesting biopolymer for developing functional clay-based bionanocomposites due to its colloidal and metal complexing properties. This work introduces novel bionanocomposites based on the assembly of sacran to sepiolite, a fibrous hydrated magnesium silicate. The prepared sacran–sepiolite bionanocomposites could be of great interest as biosorbents for the selective recovery of neodymium ions from aqueous solutions.
A layered titanate-epoxy nanocomposite was synthesized by the reaction of a layered titanate modified with glycidyl and octadecyl groups and an epoxy resin followed by curing. The nanocomposite exhibited durability toward UV light compared with the pristine epoxy resin.
Tris(2,2’-bipyridine) ruthenium(II) complex [Ru(bpy)3]2+ is one of the molecules studied most extensively for photo/ electrochemistry because of its unique combination of chemical stability and luminescence. In order to avoid aggregation of the complex, a water soluble polymer poly(vinylpyrrolidone) (PVP) was intercalated. [Ru(bpy)3]2+- fluortetrasilicic mica (TSM)-PVP intercalation compounds were prepared by cation exchange after the adsorption of PVP. The cointercalated PVP prevented self-aggregation of [Ru(bpy)3]2+ by surrounding [Ru(bpy)3]2+ in close contact in the sterically limited interlayer spaces.
PVP was intercalated into the two dimensional interlayer space of a synthetic saponite which adsorbed rhodamine 6G (R6G) by ion exchange. The expansion of the interlayer space depended on the composition. R6G degradation upon sunlight irradiation was suppressed in the presence of PVP.
Excellent Poster Award from the Forum on Low-dimensional Photo-functional Materials of Chemical Society of Japan:
Aranee TEEPAKAKORN (Vidyasirimedhi Institute of Science and Technology)
"Interactions of smectites with poly (vinyl pyrrolidone)"
Vidyasirimedhi Institute of Science and Technology (VISTEC)
Wangchan Valley 555 Moo 1 Payupnai, Wangchan, Rayong 21210 Thailand
