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276 p. Photocurable multifunctional polymer composites have been obtained and characterized according totheir photopolymerization capability, physico-chemical and functional properties. Polyurethane acrylate(PUA) has been selected as polymer matrix combined with multi-walled carbon nanotubes (MWCNT),barium titante (BaTiO3), indium tin oxide (ITO), magnetite (Fe3O4), cobalt ferrite (CFO), neodymiumiron boron alloy (NdFeB) and 1-buthyl-3-methylimidazolium tetracholonickelate ([Bmim]2NiCl4) ionicliquid (IL) to obtain different functional and multifunctional responses.Different functional and multifunctional responses have been added to the UV curable polymer,depending on the filler type and content. The inclusion of MWCNTs induce a piezoresistive responsecharacterized by GF values between 0.8 and 2.6. BaTiO3 and ITO, strongly increase the dielectricconstant from 7.5 to 25 and up to 33, respectively. In the case of Fe3O4, CFO and NdFeB, magneticcomposites with tailored magnetic properties (from hard to soft magnetic ones) are obtained. Saturationmagnetization values up to 63.86 emu/g, remanence up to 44.95 emu/g and coercivity up to 7000 Oe havebeen obtained depending on filler type and content. Finally, IL allows the preparation of temperatureactivated thermochromic humidity sensing materials with a colour change from blue to colourless,depending on relative humidity.Thus, this work successfully demonstrated the development of UV photocurable functional andmultifunctional materials, compatible with printing technologies, for electronic and sensing applications. BcMaterials: Basque Center for materials applications & nanostructures

312 p. The present thesis was focused on the development of new gel-type biomaterials form chitosan withexcellent stimuli-responsive properties using different click reactions. To this end, in the first place,chitosan was endowed with specific functionalities, after the controlled insertion of furan, maleimide,thiol or tetrazole groups in the main chain of the biopolymer, maintaining its original biocompatiblecharacter. Hereafter, hydrogels with different size and chemical structure were synthesized by means ofclick type cross-linking reactions (Diels-Alder, thiol-Michael addition or nitrile imine-mediated tetrazoleenecycloaddition). The final physico-chemical, swelling, viscoelastic and morphological properties ofthe different hydrogel systems were studied. So that the new developed biomaterials would be competentin the biomedical field, biodegradability studies under specific enzymes, controlled drug release assays,mucoadhesion experiments with mucin, antibacterial studies against Escherichia coli and Staphylococcusaureus and short-term cytotoxicity assays were conducted, depending on the intended final application. GMT :Materials Technologies Research Group