Polymer-silicate composite organic polymers polymerization within

Depending on the nature of the components used (layered silicate, organic cation, and polymer matrix) and the preparation method, three types of hybrid PCNs can be obtained [17]. Phase-separated microcomposites (conventional composites) are obtained when the polymer chains are unable to intercalate within the inorganic sheets clay lamellae remain stacked in structures marked as tactoids as in the pristine mineral. Otherwise, when the polymer chains penetrate in between the clay galleries, an intercalative system is obtained. In this case, the nanocomposite shows, at least in principle, a well-ordered multilayer morphology built up with alternating polymeric and clay layers. When clay platelets are randomly dispersed in the polymer matrix and the lamellae are far apart from each other, so that the periodicity of this platelet arrangement is totally lost, an exfoliated structure is achieved. 

In a simple approach, monomers of the guest polymer are first impregnated into a preformed porous silicate film, and subsequently polymerization is initiated either by a free radical initiator (UV, peroxides), by thermal treatment, or by electrochemical means. On the positive side, this procedure is favorable for the incorporation of linear polymers in silicates, but on the downside, some of the major advantages of composites, such as biocompatibility and adhesion to the substrate, are lost. The polymerization of organic moieties within the interconnected pores of the organic material can be carried out by two general methods that are addressed in the following text. 

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