Clay minerals are believed to play an important role in the origin of life. Bio-molecules initially formed in the shallow ocean could be adsorbed by clay minerals (e.g. montmorillonite) and/or intercalated between their interlayers, thereby protected from damage by cosmic ray and UV irradiation. The mineral particles could sink to the ocean floor and release bio-molecules under basic pH condition, such as near a highly basic hydrothermal vent. The mineral particles also serve as the location and catalyst for the polymerization of these bio-molecules, which is a crucial step in chemical evolution. As a model system, we experimentally investigated the adsorption and desorption of adenine on montmorillonite. Adsorption at pH 2.5 was found to be much larger than at pH 8.5. Since adenine is positively charged in the acidic condition, it is readily adsorbed by montmorillonite and/or intercalated into its interlayers. It was difficult to remove adenine from the interlayer, as it does not desorb in neutral or acidic (HCl) solutions. In a basic solution adenine is charge neutral, and the amount of its adsorption by montmorillonite at pH 8.5 is very small. Meanwhile, at pH 8.5, adenine in the montmorillonite interlayers is readily replaced by Na⁺ in the solution, and therefore desorbs easily. pH value clearly affects the adsorption/desorption behavior of adenine on/from montmorillonite.

The solubility product of a layered double hydrotalcite (LDH), Ksp,_LDH, was obtained for [Mg₂Al(OH)₈] [A]_l/nH₂O] with a different kind of intercalated anion, Aⁿ⁻. The pH titration of a solution containing Mg(NO₃)₂, Al(NO₃)₃ and Aⁿ⁻ salts was performed on adding an aqueous NaOH solution under CO₂⁻ free atmosphere. Ksp,_LDH was calculated from the titration curves for Aⁿ⁻ = NO₃⁻, [Fe(CN)₆]³⁻ and [Fe(CN)₆]⁴⁻. The effects of Aⁿ⁻ on the stability of LDH was discussed on the basis of the free energy change of formation.

The effect of maleic anhydride (MAH)-grafted polypropylene (PP) on the structure and mechanical properties of PP nanocomposites was examined using identical experimental conditions. MAH-grafted PP was prepared with various concentrations of MAH, using tert-butylbenzoxylate as the initiator in xylene at 140℃. The MAH grafting ratio of the resulting three samples was estimated by ¹H-NMR measurement. The MAH content were controlled to PP/MAH = 100/0.1 to 100/0.5 by mass ratio. An organically modified clay was melt-kneaded with PP and the MAH-grafted PP in a twin-screw kneader. The exfoliation of the clay layers in the polymer matrix was fairly advanced with the grafting ratio. Depending upon the morphology change, the tensile modulus of the nanocomposite is increased by a factor of roughly 1.5 compared to that of the non-reinforced polymer. Dynamic mechanical analyses (DMA) were conducted to compare the rheological properties of PP and high MAH-grafted PP systems. The incorporation of clay layers in the MAH-grafted PP led to a considerable increase in the storage modulus (E') and a shift to higher temperatures in the α relaxation peaks for polymer.