Polymer interlayer expandable

Micro-composites are formed when the polymer chain is unable to intercalate into the silicate layer and therefore phase separated polymer/clay composites are formed. Their properties remain the same as the conventional micro-composites as shown in Figure 2(a). Intercalated nano-composite is obtained when the polymer chain is inserted between clay layers such that the interlayer spacing is expanded, but the layers still bear a well-defined spatial relationship to each other as shown in Figure 2(b). Exfoliated nano-composites are formed when the layers of the day have been completely separated and the individual layers are distributed throughout the organic matrix as shown in Figure 2(c). 

Vermiculites. Vermiculites are 2 1 expanding minerals with a structure similar to micas (Table 7-4). They are considered to be derived from the alteration of micas (Douglas, 1977). Cation exchange capacity is high, as is the surface area. Potassium or NHj in solution tends to be strongly fixed by vermiculites. Upon fixation of these ions, the CEC decreases and the properties of vermiculite become like those of mica. In acid soil, hydroxy aluminum polymers can be fixed in the interlayer position to form an "island-like" structure (Jackson,... 

In the early nineties, clays once more have come to the attention of researchers because thermally and hydrothermally stable expanded materials have been synthesized by interlayering 2 1 clay minerals with oligomeric molecules and colloidal particles derived from the hydrolysis of polyvalent cations. On heating, these inorganic polymers (or colloidal particles) form pillars that permanently prop open the clay layers generating high surface area solids enclosing cavities available to sorption and catalysis. 

The immiscible state corresponds to the situation in which the individual silicate layers do not separate at aU and are confined to multilayer stacks, which may even be agglomerated, as expected when the silicates are incompatible with the polymer matrix. The intercalated state is typically described as a situation in which the sihcate layers expand to accommodate some small number of polymer molecules, but where the layers retain a relatively small interlayer spacing and an ordered layered structure, analogous to the swelling of a multilayer stack. Finally, the exfoliated state refers to the situation in which the sihcate layers are individually dispersed. 

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