Resumen de Development of polymeric nanocomposites with enhanced distribution of catalytically active or bactericide nanoparticles
This PhD thesis is an interdisciplinary work aimed at obtaining new nanocomposites synthesized from functional ion-exchange polymeric materials modified with nanoparticles (NPs) of different composition.
The development of nanomaterials is of great current interest because of their special properties that differ from those of matter on a macroscopic scale and can result in technological advantages. However, there is some concern about the toxicity of those materials.
Therefore, in this work we have developed a new method for the manufacture of nanomaterials with two levels of safety: the NPs stabilization in the polymer matrix and their magnetic retention. The Intermatrix Synthesis (IMS), method developed in this work, controls the growth and stabilization of the NPs. It also allows obtaining mono-or bicomponent NPs with core-shell structure. The core component of these structures can be an economic material and/or a material with some additional property of interest (e.g., magnetism). The core is coated with a specific functional material for the corresponding application of interest. Also, the magnetic core allows the recovery of the NPs which could be leached, for example, from a disinfection treatment and, thus, avoiding the possible toxicity from the NPs. Similarly, the recovery of NCs with catalytic properties in order to reuse them in successive catalytic cycles can also take place.
Thus, in this work the IMS technique has been optimized for obtaining monocomponent NPs (Ag, Co, Pd or Fe3O4) and bicomponent core-shell NPs (Ag@Co, Ag@Fe3O4 or Pd @Co) stabilized in polymeric matrices of various physical types (films, fibres and resins) containing different functional groups (sulfonic, carboxylic or ammonium salts).
Furthermore, we have characterized the different nanocomposites to evaluate their properties. Microscopic techniques (e.g., SEM and TEM) provide information about the size and location of the NPs within the material. Other techniques (e.g., ICP-AES, XRD, XANES or SQUID) have yielded information on the composition and magnetic properties of NPs and nanocomposites. The distribution of the NPs, concentrated on the surface of the matrix, is due to the Donnan-exclusion effect and some other various parameters optimized regarding the synthesis and polymer characteristics. Thus, the NPs are maximally accessible to the species involved in the application of interest. On one hand, the catalytic activity of Pd- and Pd@Co-based nanocomposites for the reaction of Suzuki cross-coupling has been shown and optimized. Also, the application of Ag and magnetic core-based nanocomposites as antibacterial agents for water treatment has been studied obtaining successful results.
All in all, we believe this work provides and consolidates knowledge of interest related to polymer-metal nanocomposite materials and the evaluation of their applications.
