Percorrer por autor "Arbelaiz, Aitor"
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- Bacteriostatic ecffect of waterborne polyurethane-ureia films containing bioactive plant extracts incorporated by different routesPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Arbelaiz, Aitor; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaThe environmental awarenessh as promoted the development of new materiats towards eco-friendty systems based on both,green synthesis processes as well as the renewable origin of the raw compounds. In this way,focusing on synthesis methods, the use of waterborne polyurethane-urea dispersions have gained attention due to their versatility leading to a wide variety of apptications broadening the range of appLications. In addition, it is worth nothing that the dispersibitity in water offers the possibitity of incorporating soluble additives such as plant extracts. Therefore, in this work Melissa officinalis L . ptant was setected in order to obtain bioactive plant extract, in order to be incorporated to a waterborne polyurethane-urea disspersion varying their content as well as using three differernt incorporation routes. These dispersions were characterized and employed in the preparation of films which were analyzed from the viewpoint of physicochemical, thermal and mechanical properties, among others. Finatty, the antibacterial properties of the films were analyzed after 1 and 4 days of incubation. Where it was observed that the content and incorporation route of the extract influenced in the behavior of the films against common pathogens (Staphylococcus aureus, Escherichio coli ond Pseudomonas aeruginosa.
- Bioinks functionalized with natural extracts for 3D printingPublication . Larraza, Izaskun; Santamaria-Echart, Arantzazu; Fernandes, Isabel Rodrigues; Barreiro, M.F.; Arbelaiz, Aitor; Eceiza, ArantaxaIn the search of materials valid for direct ink writing (DIW) 3D printing and with special interest for the biomedical and pharmaceutical applications, the development of bioactive inks for DIW is of great interest. For that purpose, in this work bioactive waterborne polyurethane–urea inks were prepared by addition of natural extracts (logwood, chestnut, and alder buckthorn) and cellulose nanofibers (CNF). The rheological behavior of the inks proved to be strongly dependent on the extract type and content, and the addition route used. Inks prepared by ex-situ incorporation of the extracts showed a strong gel-like behavior, as did inks prepared with chestnut and alder buckthorn extracts, which, in turn, hindered a continuous flow during the printing process, resulting in 3D printed parts with poor shape fidelity. On the other hand, inks prepared insitu and with logwood extract showed more facility to flow and higher homogeneity, which translated in better printability and better shape fidelity, further enhanced for CNF containing inks. 3D printed composites showed reinforced mechanical behavior, as well as in materials with enhanced antibacterial behavior. Overall, the possibility to successfully prepare bioactive inks valid for 3D printing was proven.
- Modulating the microstructure of waterborne polyurethanes for preparation of environmentally friendly nanocomposites by incorporating cellulose nanocrystalsPublication . Santamaria-Echart, Arantzazu; Ugarte, Lorena; Arbelaiz, Aitor; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaIncreasing environmental awareness has promoted development of ecofriendly materials incorporating renewable raw materials and using green synthesis routes such as waterborne dispersion, avoiding employment of organic solvents and thus reducing generation of volatile organic compounds. In this regard, waterborne polyurethanes (WBPU) present an opportunity to tailor material properties while meeting application requirements and avoiding use of organic solvents. In addition, WBPU dispersions offer the possibility to incorporate hydrophilicwater-dispersible reinforcement materials, such as cellulose nanocrystals (CNC), which represent a suitable candidate for preparation of nanocomposites due to their renewability, availability, and unique properties resulting from their nanoscale dimension. Therefore, in this work, different WBPU having small particle size with narrow distribution were synthesized at various isocyanate/hydroxyl (NCO/OH) group ratios, and CNC were isolated for preparation of nanocomposites with 1, 3, or 5 wt% CNC by solvent casting. It was observed that, just by varying the NCO/OH ratio, the polyurethane microstructure was altered, resulting in different ordered structures. At low NCO/OH ratio, soft ordered domains were observed, whereas at higher NCO/OH ratio, hard ordered domains were obtained. These different microstructures of the matrix induced different behaviors of the CNC reinforcement, acting either as crystal growth inhibitor or nucleating agent, thereby modulating the properties of the final material in different ways.
- Waterborne polyurethane-urea dispersion with chain extension step in homogeneous medium reinforced with cellulose nanocrystalsPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Ugarte, Lorena; Barreiro, M.F.; Arbelaiz, Aitor; Corcuera, Maria Angeles; Eceiza, ArantaxaWaterborne polyurethane-urea (WBPUU) dispersions have gained attention towards environmentally-friendly synthesis routes. Differing from the conventional WBPUU synthesis route where the diamine chain extension is performed in heterogeneous medium in the surface of the already formed particles, in this case the chain ex- tension was carried out in homogeneous medium, prior to WBPUU nanoparticles formation. Thus, stable WBPUU dispersion with small particle sizes and narrow distribution was synthesized. Furthermore, cellulose nanocrystals (CNC) were isolated for the preparation of eco-friendly nanocomposites just by mixing. Nanocomposites with different CNC contents were prepared and extensively characterized in terms of physicochemical, thermal, thermomechanical and mechanical properties, hydrophilic behavior and morphology.