Polymer/clay nanocomposites synthesis

Meneghetti, P. and Qutubuddin, S. 2006. Synthesis, thermal properties and applications of polymer-clay nanocomposites. Thermochimica Acta 442 74-77. 

There are three general approaches to the synthesis of polymer-clay nanocomposites. In the first approach, a monomer or precursor is mixed with organophilic clay and followed by polymerization. This in situ polymerization technique was first developed by the... 

As reflected in this chapter, most of the published literature on polymer-clay nanocomposites focuses on synthesis and characterization. Future work should address is-... 

Usuki, A., Hasegawa, N. and Kato, M. Polymer-Clay Nanocomposites. Vol. 179, pp. 135-195. Uyama, H. and Kobayashi, S. Enzymatic Synthesis and Properties of Polymers from Polyphenols. Vol. 194, pp. 51-67. 

In the past decade, clay-based polymer nanocomposites have attracted considerable attention from the research field and in various applications. This is due to the capacity of clay to improve nanocomposite properties and the strong synergistic effects between the polymer and the silicate platelets on both a molecular and nanometric scale [2,3], Polymer-clay nanocomposites have several advantages (a) they are lighter in weight than the same polymers filled with other types of fillers (b) they have enhanced flame retardance and thermal stability and (c) they exhibit enhanced barrier properties. This chapter focuses on the polymer clay-based nanocomposites, their background, specific characteristics, synthesis, applications and advantages over the other composites. 

K.A. Cairado, L. Xu, In Situ synthesis of polymer-clay nanocomposites from silicate gels. Chemistry of Materials 10 (1998) 1440-1445. 

Soft nanohybrid materials with novel organic-inorganic network structures, such as nanohydrogels, soft nanocomposites (solid), and their derivatives are described in the chapter Soft Nanohybrid Materials Consisting of Polymer-Clay Networks. Synthesis of polymer hybrids based on metal-oxide nanoparticles are discussed in Fabrication of Metal Oxide-Polymer Hybrid Nanocomposites. Some properties and applications of these hybrid nanocomposites are also discussed in this chapter. 

Bottcher and coworkers were the first to report the preparation of polymer clay nanocomposites by ATRP [20]. ATRP initiator-modified layered silicate was prepared by ion exchange between clay and l,T-(N,N,N-trimethylammonium bromide)undecanyl-2-bromoisobutyrate in-situ ATRP was carried out to grow polymer chains from the clay surface. In-situ ATRP between individual silicate layers leads to the direct synthesis of dispersed silicate nanocomposites. Their kinetics study and molecular weight analysis demonstrated that the polymerization followed the ATRP mechanism. 

Templated synthesis of polymer-clay nanocomposites Synthetic flnoro-smectite/ polyvinylpyrrolidone Carrado and Xu (111)... 

FIGURE 17 Schematic representation of the templating synthesis pathway employed to prepare polymer-clay nanocomposites that generate the clay under hydrothermal conditions in the presence of the polymer. 

The model illustrated in Figure 2 summarizes the overall mechanism for formation of epoxy polymer - clay nanocomposites. Upon solvation of the organoclay by the epoxide monomers, the gallery cations reorient from their initial monolayer, lateral bilayer, or inclined paraffin structure to a perpendicular orientation with epoxy molecules inserted between the onium ions. A related reorientation of alkylammonium ions has been observed previously for e-caprolactam intercalated clay intermediates formed in the synthesis of Nylon-6 -exfoliated clay nanocomposites (9). Thus, the ability of the onium ion chains to reorient into a vertical position in order to optimize solvation interactions with the monomer may be a general prerequisite for pre-loading the clay galleries with sufficient monomer to achieve layer exfoliation upon intragallery polymerization. 

It seems that further research on polymer-clay nanocomposites would focus on the synthesis of organic modifiers with enhanced thermal stability and providing additional functionalities for formation of interfacial bonds and interaction through, for example, graft polymerization. 

Polymer/clay nanocomposites exhibit remarkable improvement in material properties relative to unfilled polymers or conventional composites. These improvements can include increased tensile modulus, mechanical strength, and heat resistance and reduced gas permeability and flammability [1], There are various methods of preparing polymer/clay nanocomposites (i) in situ polymerization, (ii) solution intercalation, (iii) melt intercalation, and (iv) in situ template synthesis [2],... 

Intercalation of polymers in layered hosts, such as layered silicates, has proven to be a successful approach to the synthesis of PLS nanocomposites. These polymer/ clay nanocomposites can be prepared in several ways, namely, solution exfoliation, melt intercalation, in situ polymerization, and template synthesis [9]. 

Kaminsky [92] was the first to report a method in which the filler surfaces were treated with metallocene-based catalyst for the production of filled polyolefins. In this method, at first under inert atmosphere, the clay surface is treated with an alkylaluminum compound to reduce the residual water content. In the second step, the catalyst or cocatalyst solution is impregnated onto the clay surface followed by washing with an anhydrous solvent to avoid excess catalyst leaching from the support during the polymerization. Additional alkylaluminum compounds may be used during the course of polymerization. This polymerization-filling technique is a widely used procedure for the synthesis of polymer/clay nanocomposites using coordination catalysts [60, 93, 94]. 

Optimization technique and effective synthesis o f biobased polymer/clay nanocomposites... 

Murray CB, Kagan CR, Bawendi MG (2000) Synthesis and characterizati(Hi of mrmodisperse nanocrystals and close-packed nanocrystal assemblies. Ann Rev Mater Res 30(1) 545-610 Nikonorova NA, Barmatov EB, Pebalk DA, Barmatova MV, Dommguez-Espinosa G, Diaz-Calleja R, Pissis P (2007) Electrical properties of nanocomposites based on comb-shaped nematic polymer and silver nanoparticles. J Phys Chem C 111(24) 8451-8458 Okamoto M (2004) Encyclopedia of nanoscience and nanotechnology. In Nalwa HS (ed) Polymer/clay nanocomposites, vol 8. American Scientific, Stevenson Ranch, pp 791-843 Osipov MA, Gorkunov MV (2014) Molecular theory of phase separation in nematic liquid crystals doped with spherical nanoparticles. ChemPhysChem 15(7) 1496-1501... 

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