Polymer Clay Nanocomposites by In-situ Atom Transfer Radical Polymerization

Polymer Clay Nanocomposites by In-situ Atom Transfer Radical Polymerization 

Since the publication of Toyota s pioneering work on polymer-silicate (or clay) nanocomposites, the preparation of polymer clay nanocomposites has attracted intense interest in the materials science community [1-6]. By introducing a few weight percent of clay into the polymer matrix, many properties of these nanocomposites will be improved, such as mechanical properties [7], thermal stability [8], and flam retardance [9], 

Most commonly used layered silicate is montmorillonite clay, which is composed of micron-sized particles. The particles are constructed of platelets with thickness of lnm and width of 100-200 nm. Platelets have permanent negative charge and they are held together by charge balancing cations such as Na or Ca [2-i] ions. The significant disruption of individual silicate layers in polymer matrix with nanoscopic dimensions (exfoHated structure) leads to improvements of the nanocomposite properties. However, in many cases, the isolated silicate layers are not completely dispersed throughout the polymer matrix, instead, the clay particles in polymer matrix maintain the hierarchical architecture, and an interlayer expansion occurs (intercalated structure). 

In the in-situ polymerization technique, the cations in the intergallery space of the clay are exchanged to organic ammonium salts (monomers or initiators), which leads to the expansion of the gap between the clay platelets. The in-situ polymerizations are conducted between the intercalated layers. Various different polymerization technologies were employed for preparing polymer clay 

In-situ Synthesis of Polymer Nanocomposites, First Edition. Edited by Vikas Mittal. 

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I 70 Polymer Clay Nanocomposites by In-situ Atom Transfer Radical Polymerization a) b)... 

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