Poly(ethylene terephthalate) nanocomposites using nanoclays modified with thermally stable surfactants

The term “nanocomposite” is widely used to describe a very broad range of materials, where one of the phases has a submicrometer dimension [1–4].1 In the case of polymerbased nanocomposites, this typically involves the incorporation of “nano” fillers with one (platelets), two (fibers, tubes), or all three dimensions at the submicrometer scale. However, strictly speaking, simply using nanometer-scaled fillers is not sufficient for obtaining genuine/true nanocomposites [5]: these fillers must also be well dispersed down to individual particles and give rise to intrinsically new properties, which are not present in the respective macroscopic composites or the pure components. In this chapter, we shall use a broader definition, encompassing also “nanofilled polymer composites” [5], where – even without complete dispersion or in the absence of any new/novel functionalities – there exist substantial concurrent enhancements of multiple properties (for example, mechanical, thermal, thermomechanical, barrier, and flammability). Further, we shall limit our discussion to one example, focusing on poly(ethylene terephthalate) (PET) with mica-type layered aluminosilicates. The fact that nanometer-thin layered inorganics can be dispersed in macromolecular matrices is ubiquitous in nature, and it has also long been established in the laboratory; for example, synthetic polymers were shown to disperse appropriately-modified clay minerals before the 1960s [6, 7]. However, the field of polymer/layered-silicate