Polymeric and Soft Nanocomposites Based on Cyclodextrin-Modified Barium Titanate Nanoparticles

Resumen

The Ph.D. Thesis presented with the title “Polymeric and soft nanocomposites based on cyclodextrin-modified barium titanate nanoparticles” is the outcome of a few years of research on different topics covering nanomaterials, nanocomposites, polymers and cyclodextrins. In the next few lines a summary of the contents is presented. There are two guiding threads, Barium Titanate (BT) nanoparticles and Cyclodextrins (CDs), which had never been combined before this project was started. Barium Titanate is commonly known for its dielectric and piezoelectric properties, and CDs are known as stabilizing and solubilizing agents. Our idea is to prepare different kinds of polymeric nanocomposites that have in common the presence of BT as a filler, with special interest in nanocomposites from soluble polymeric precursors. For that purpose, CDs are proposed as a tool to stabilize the dispersion of the nanoparticles in the polymer solution. On a first step, we present the preparation of nanocomposites based on the thermoplastic polymer Ethylene Vinyl Acetate (EVA) and BT by means of a novel technique: cryogenic High Energy Ball Milling (HEBM). The analysis and characterization of the results show a successful dispersion of the nanoparticles within the nanocomposite. Further on, with the idea of introducing the CD in the surface of the nanoparticles in mind, we studied the inclusion complex of βCD and Rhodamine B (RhB), a fluorescent probe, characterizing it in solution and in solid state. This serves as a proof of concept for the ability of the CD to encapsulate molecules of interest for transport and further release. The next step was the modification of the BT surface to make them stable in water solution. Different approaches were studied, and the successful one with βCD, was optimized and fully characterized, with a special interest in the cytotoxicity results of the modified nanoparticles. Finally, after the good results of the modified nanoparticles in terms of cytotoxicity, the culmination of the project is the preparation and characterization of a hydrogel nanocomposite based on the poloxamine Tetronic® 1107. This soft nanocomposite combines the characteristic properties of BT and the host-guest complexation ability of the CDs. At the same time, the introduction of the nanoparticles in the hydrogel allows for the tailoring of the gelling properties, as well as an improvement of the mechanical properties of the hydrogel.