## 1 Introduction  
The production of polymer nanocomposites containing layered silicates (clays) has been a case of great interest for many industries through the last decades, for example, automotive, aerospace, sports, pharmaceuticals, and others [1, 2]. The increased research activity on polymer/clay nanocomposites may be attributed to the great improvement in properties achieved when using clay nanoadditives [3, 4], combined with the fact that clays are natural products in high abundance and with rich intercalation chemistry [5, 6]. Nylon was the first type of polymer used to produce clay nanocomposites commercially [7], and since then, numerous types of polymers have also been used as matrices, such as epoxies [8], polyesters [9], polyglycols [10], and other. Homogeneous dispersion of silicate nanolayers is the key point for attaining the maximum benefit of polymer/clay interaction and many physical and chemical methods have been implemented for this purpose. Most of these composites are prepared by melt-mixing processes (e.g., extrusion, injection, or mixing). These processes are considered as some of the most rapidly growing technologies and are already used widely, except for those of polymer and food processing, also in drug delivery research [11] and pharmaceutical product development [12; 13; 14; 15; 16; 17; 18; 19]. Melt mixing is a process that involves the mixing of a polymer, one or more active pharmaceutical ingredients (APIs), and perhaps other additives such as clays or other excipients, at elevated temperatures just above their melting point to provide a molten material of uniform shape by using processing machines equipped with one or more rotating screws. This process offers many advantages as it is a solvent-free technique, which is an important environmental consideration, and provides the ability of continuous operation while being economically viable at the same time, since a lot of processing steps can be eliminated [20]. Thus, less time is needed for the preparation of the final formulation. Furthermore, melt mixing enhances the solubility of poorly water-soluble drugs and hence it improves the APIs' bioavailability [21; 22; 23; 24; 25]. Various types of polymers have been used for the development of drug-loaded systems via hot melt processes, and poly(ethylene oxide) (PEO) is one of them. PEO is a semicrystalline, hydrophilic, nonionic, water-soluble polymer, with a relatively low melting point (below 80 \({}^{\circ}\)C for PEO used in this study (M\({}_{\rm v}\) \(\sim\)2,000,000 g/mol). PEO has been used as the matrix of several release systems [26] and as a carrier of drugs such as ibuprofen [27], ketoprofen [28], and flurbiprofen [29]. PEO creates a matrix inside which the drug is trapped and generally homogeneously distributed. When the carrier/drug system is administered, the already-existing water penetrates the system, which leads to the swelling of the polymer and the drug's dissolution. Once the carrier system is dissolved, the drug starts to diffuse, going through the polymeric matrix, while the PEO chains start to disentangle and result in system erosion [30; 31]. Except in a polymer matrix, the addition of nanoadditives such as clays, SiO\({}_{2}\), TiO\({}_{2}\), carbon-based nanomaterials, and so forth also plays an important role in drug dissolution. Polymeric nanocomposite materials are used in drug delivery system applications with the nanofiller playing a crucial double functionality. Concerning the drug, nanofillers can act as transport vehicles/carriers for the efficient delivery of therapeutic molecules by modifying the rate and/or time of release, increasing the stability of the drug, or improving the dissolution profile of a drug concerning self-healing [32; 33]. The high surface area of nanoadditives (200-1500 m\({}^{2}\)/g) is an advantage that cannot be found in polymeric matrices because drug can be dispersed in a huge surface area, increasing in most cases its dissolution rate.