Browsing by Author "Eceiza, Arantaxa"
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- Advances in waterborne polyurethane and polyurethane-urea dispersions and their eco-friendly derivatives: a reviewPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaPolyurethanes and polyurethane-ureas, particularly their water-based dispersions, have gained relevance as an extremely versatile area based on environmentally friendly approaches. The evolution of their synthesis methods, and the nature of the reactants (or compounds involved in the process) towards increasingly sustainable pathways, has positioned these dispersions as a relevant and essential product for diverse application frameworks. Therefore, in this work, it is intended to show the progress in the field of polyurethane and polyurethane-urea dispersions over decades, since their initial synthesis approaches. Thus, the review covers from the basic concepts of polyure-thane chemistry to the evolution of the dispersion’s preparation strategies. Moreover, an analysis of the recent trends of using renewable reactants and enhanced green strategies, including the current legislation, directed to limit the toxicity and potentiate the sustainability of dispersions, is described. The review also highlights the strengths of the dispersions added with diverse renewable additives, namely, cellulose, starch or chitosan, providing some noteworthy results. Similarly, dispersion’s potential to be processed by diverse methods is shown, evidencing, with different examples, their suitability in a variety of scenarios, outstanding their versatility even for high requirement applications.
- 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.
- Development of waterborne polyurethane-ureas added with plant extracts: Study of different incorporation routes and their influence on particle size, thermal, mechanical and antibacterial propertiesPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Barreiro, M.F.; Retegi, Aloña; Eceiza, Arantaxa; Corcuera, Maria AngelesPolyurethane-ureas are a versatile family of polymers which can be employed in a wide range of applications. Among them, waterborne polyurethane-urea (WBPUU) dispersions are gaining relevance in the field of environmentally-friendly products since their productive process adopts green synthesis routes, avoiding the use of organic solvents. Furthermore, their waterborne character can be exploited to incorporate several water compatible ingredients able to confer functional properties to the final materials. Among them, plant extracts, which are known to have relevant bioactivities, can be viewed as interesting candidates. Therefore, in this work, two extracts known to present antimicrobial activity (Melissa officinalis L. and Salvia officinalis L.) were obtained by the infusion method and incorporated into the WBPUU (1, 3 and 5 wt%) following different incorporation routes comprising its adding during different phases of the productive process (post-, in-situ and pre- methods). Thereafter films were prepared by solvent-casting and characterized from the viewpoint of physicochemical, thermal, mechanical, thermomechanical and antibacterial properties and morphologically. The studied incorporation routes resulted in different intercalation mechanisms that varied from extract positioned among the polyurethane-urea nanoparticles (post-method) to extract partially embedded inside them (in-situ and pre-methods), which produced stiffening or flexibilizing effects in the produced films, enhancing in general the antimicrobial characteristics of films after 4 days of incubation comparing with base WBPUU, especially when the extract is embedded.
- Different environmentaly-friendly strategies for loading waterborne polyurethane and polyurethane-urea dispersionsPublication . Santamaria-Echart, Arantzazu; Ugarte, Lorena; Fernandes, Isabel P.; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaThe environmental awareness has increased the research and development of eco-friendly green synthesis routes for many different applications, such as the waterborne polymer systems. Among others, waterborne polyurethanes (WBPU) and waterborne polyurethane-ureas (WBPUU) have gained attention due to their versatility in terms of composition and properties, making them suitable in a wide range of applications [1]. WBPU and WBPUU synthesis process is based on the incorporation of internal emulsifiers covalently bonded to the polymer obtaining stable water dispersions over months. Furthermore, the waterborne character of the dispersions provides the opportunity of incorporating water dispersible nanoentities and water soluble additives, enhancing or even providing additional properties. In this context, the use of renewable derivatives opens the possibility of enhancing the environmentally-friendly character. Among them, cellulose nanocrystals (CNC) are presented as a suitable candidate for the preparation of nanocomposites, considering their unique properties in the nanoscale dimension, provided by their high length/diameter aspect ratio and high specific mechanical properties [2]. Otherwise, the incorporation of natural water soluble additives has focused attention on extracts obtained from plants, consisting in biologically active compounds [3], whose antimicrobial character can determine the antimicrobial behavior of the WBPU and WBPUU. Therefore, in this work, different strategies have been analyzed for the preparation of WBPU-CNC nanocomposites and WBPUU-plant extracts varying their content as well as their incorporation route.
- Flexible polyurethane foams based on 100% renewably sourced polyolsPublication . Ugarte, Lorena; Saralegi, Ainara; Fernández, Rocío; Martín, L.; Corcuera, Maria Angeles; Eceiza, ArantaxaSince polyol is one of the major components in polyurethane foam synthesis, introducing renewably sourced polyols in the foam formulation leads to materials with high renewable carbon content. A series of flexible polyurethane foams with variations in polyol composition were synthesized with castor oil based Lupranol Balance ® 50 polyether polyol and corn based polytrimethylene ether glycol mixtures. Water was used as the unique and eco-friendly blowing agent. The effect of the relative amount of each polyol on the structure and properties was analyzed by optical microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, tensile and compressive tests, dynamic mechanical analysis and atomic force microscopy. The average molecular weight and hydroxyl number of the polyol components showed to influence the foaming reaction and hence the structure and properties of the polyurethane foam. The newly developed peak force quantitative nano-mechanics technique was used to map the elastic modulus values of foam cell struts and it seemed to be adequate to assess the purity of the different phases.
- Green nanocomposites from Salvia-based waterborne polyurethane-urea dispersions reinforced with nanocellulosePublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Ugarte, Lorena; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaWaterborne polyurethane-urea (WBPUU) dispersions, products having none or low contents of organic solvents, depending on the used synthesis process, can provide suitable environmentally-friendly strategies to prepare novel materials. Moreover, waterborne systems enable the incorporation of aqueous dispersible nanoentities and soluble additives, which provides a strategy to design versatile functional materials with tailored properties. Having demonstrated in previous work the bacteriostatic properties of a 3 wt% Salvia-based WBPUU against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, this work is focused in the preparation of Salvia-based WBPUU added with cellulose nanocrystals (CNC) tackling the preparation of functional green nanocomposite films with increased mechanical properties. Through this strategy, nanocomposites loaded with 1, 3 and 5 wt% of CNC were prepared, showing an effective CNC incorporation avoiding agglomerates. CNC addition is able to modulate soft and hard phase's segregation, inducing enhanced mechanical stiffness, together with improved deformability, while retarding thermomechanical instability to higher temperatures.
- 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.
- Polyurethane films prepared with isophorone diisocyanate functionalized wheat starchPublication . Hosseinpourpia, Reza; Adamopoulos, Stergios; Santamaria-Echart, Arantzazu; Eceiza, ArantaxaThis study reports the fabrication and performance of sustainable polyurethane (PU) films based on wheat starch (native NS, modified MS), bio-polyols (1,3-propanediol PD, glycerol Gly), and polymeric diphenylmethane diisocyanate (pMDI). NS was successfully modified with isophorone diisocyanate, confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). Various PU films were prepared using NS, PD or Gly, MS and pMDI. For comparison, reference films were also synthesized without MS. PU films were analyzed from the viewpoint of their chemical, thermomechanical and flexural properties, and microstructural morphology. FTIR spectra demonstrated the total consumption of NCO groups, while the scanning electron microscopy micrographs of the films revealed that MS addition promoted the interactions between the compounds, enhancing in consequence their mechanical and thermomechanical performance. The study supported the suitability of functionalized carbohydrates to substitute petrochemical compounds in the synthesis of more environmentally-friendly PUs.
- Synthesis of waterborne polyurethane-urea dispersions with chain extension step in homogeneous and heterogeneous mediaPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Saralegi, Ainara; Costa, Mário Rui; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaHypothesis: The possibility of tailoring the final properties of environmentally friendly waterborne polyurethane and polyurethane-urea dispersions and the films they produce makes them attractive for a wide range of applications. Both the reagents content and the synthesis route contribute to the observed final properties. Experiments: A series of polyurethane-urea and polyurethane aqueous dispersions were synthesized using 1,2-ethanediamine and/or 1,4-butanediol as chain extenders. The diamine content was varied from 0 to 4.5 wt%. Its addition was carried out either by the classical heterogeneous reaction medium (after phase inversion step), or else by the alternative homogeneous medium (prior to dispersion formation). Dispersions as well as films prepared from dispersions have been later extensively characterized. Findings: 1,2-Ethanediamine addition in heterogeneous medium leads to dispersions with high particle sizes and broad distributions whereas in homogeneous medium, lower particle sizes and narrow distributions were observed, thus leading to higher uniformity and cohesiveness among particles during film formation. Thereby, stress transfer is favored adding the diamine in a homogeneous medium; and thus the obtained films presented quite higher stress and modulus values. Furthermore, the higher uniformity of films tends to hinder water molecules transport through the film, resulting, in general, in a lower water absorption capacity.