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Item type:Publication, Bacterial-Polymer-Based Electrolytes: Recent Progress and Applications(American Chemical Society, 2020-12-28)Bacteria can naturally synthesize a wide range of biopolymers that have appealing material properties for numerous applications. In the past decade, the development of green electronics based on bacterial polymers has gained major attention. Polymer electrolytes are key components in electrochemical devices owing to their mechanical properties, thermal stability, and ionic conductivity. The present review focuses on the recent progress of bacterial-polymer-based electrolytes and their applications in electrochemical energy conversion and storage. First, we described the ion transfer mechanism of polymer electrolytes and the multiple approaches for improving ionic conductivity and mechanical properties. Then, we summarized the composition, performance, and approaches applied for the development of multiple bacterial polymer electrolytes, namely, polysaccharides, polyanhydrides, and polyesters. Lastly, the practical applications of bacterial-polymer-based electrolytes in electrochemical energy storage and conversion, namely, fuel cells, batteries, supercapacitors, and other electrochemicals, are reviewed. Bacterial polymer electrolytes are presented as a fruitful, eco-friendly, and high-performance alternative for traditional solid polymer electrolytes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Mechanical properties of calcite- and aragonite-based structures by nanoindentation tests(ICE Publishing, 2020-06-05)Nacre has been considered as one of the most important models for the development of hard bioinspired materials. This aragonite-based layered structure has been extensively studied because of its excellent mechanical properties, superior to those of monolithic aragonite. Calcite-based seashells have received less attention, as they display lower hardness and Young's modulus. However, layered calcitic structures also have a superior fracture toughness value compared with monolithic calcite. In this paper, seashells of six species were studied by correlating the mechanical properties of the calcite- and aragonite-based layers with their mineral building blocks. Morphological studies revealed nacreous and fibrous prismatic microstructures for aragonite-based layers, whereas calcite-based layers have prismatic and foliated microstructures. The hardness and stiffness of the aragonitic structures were slightly higher than those of calcite. A toughening factor was calculated comparing the fracture toughness of the aragonitic and calcitic layers with the toughness of monolithic aragonite and calcite. The toughening factors of calcitic and aragonitic structures were in the same range (1.6-9.2). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Synthesis of highly stable κ/ι-hybrid carrageenan micro- and nanogels via a sonication-assisted microemulsion route(SAGE Publishing, 2020-08-01)Novel carrageenan micro- and nanogels were developed via a sonication-assisted microemulsion processing route. The diameter of the dry samples ranged 197.3 −421.35 nm whereas the diameter of the samples suspended in water ranged 467.8–605.9 nm. Hybrid κ/ι-carrageenan, rather than κ- or ι-carrageenan was used for the first time for the preparation of micro- and nanogels. KCl was used as a cross-linking agent and Tween 80 was used as surfactant. The micro- and nanogels suspended in water were found to simultaneously exhibit a lower diameter, and a lower swelling ratio with higher Tween 80 content. The micro- and nanogel suspension yields a zeta potential value of −50.5 mV, superior to values reported elsewhere for pure κ- or ι-carrageenan micro- and nanogels. The high stability was attributed to the high hydrophile-lipophile balance (HLB = 15) value of Tween 80. These results suggest that hybrid κ/ι-carrageenan micro- and nanogels are promising candidates for smart therapeutics applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Application of the Spider Silk Standardization Initiative (S3I) methodology to the characterization of major ampullate gland silk fibers spun by spiders from Pantanos de Villa wetlands (Lima, Peru)(Elsevier, 2020-11-01)Spider silk is a natural material with unique properties and a great potential for engineering and biomedical applications. In spite of its simple composition and highly conserved and stereotypical production, spider silks show a wide range of variability in their mechanical properties which, for long, have defied their classification and standardization. Here we propose to launch the Spider Silk Standardization Initiative (S3I), a methodology based on the definition of the α* parameter, in an attempt to define a systematic procedure to classify the tensile properties exhibited by major ampullate gland silk (MAS) spun by Entelegynae spiders. The α* parameter is calculated from the comparison of the true stress-true strain curve of any MAS fiber after being subjected to maximum supercontraction, with the true stress-true strain curve of the species Argiope aurantia, which is set as a reference curve. This work presents the details of the S3I methodology and, as an example, shows its application to an assemblage of Entelegynae spiders from different families collected at the Pantanos de Villa wetlands (Lima, Peru). The systematic and objective classification of the tensile properties of MAS fibers allowed by the S3I will offer insights into key aspects of the biological evolution of the material, and address questions such as how history and adaptation contributed to shape those properties. In addition, it will surely have far reaching consequences in fields such as Materials Science, and Molecular and Evolutionary Biology, by organizing the range of tensile properties exhibited by spider silk fibers. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bacterial cellulose—graphene based nanocomposites(MDPI, 2020-09-02)Bacterial cellulose (BC) and graphene are materials that have attracted the attention of researchers due to their outstanding properties. BC is a nanostructured 3D network of pure and highly crystalline cellulose nanofibres that can act as a host matrix for the incorporation of other nano-sized materials. Graphene features high mechanical properties, thermal and electric conductivity and specific surface area. In this paper we review the most recent studies regarding the development of novel BC-graphene nanocomposites that take advantage of the exceptional properties of BC and graphene. The most important applications of these novel BC-graphene nanocomposites include the development of novel electric conductive materials and energy storage devices, the preparation of aerogels and membranes with very high specific area as sorbent materials for the removal of oil and metal ions from water and a variety of biomedical applications, such as tissue engineering and drug delivery. The main properties of these BC-graphene nanocomposites associated with these applications, such as electric conductivity, biocompatibility and specific surface area, are systematically presented together with the processing routes used to fabricate such nanocomposites. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Molecular α-relaxation process of exopolysaccharides extracted from Nostoc commune cyanobacteria(Elsevier, 2020-10-15)Broadband dielectric spectroscopy was used to investigate the molecular α-relaxation of the exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria. The EPS were modified in different ways. EPS were carboxymethylated to obtain carboxymethyl-exopolysaccharides (CEPS). EPS and CEPS were doped with ammonium iodide and 1-butyl-3-methylimidazolium chloride. An α relaxation process was observed for all specimens. The temperature dependence of the relaxation times for pure and doped, EPS and CEPS polymers exhibited non-Arrhenius behavior. This relaxation process was associated with the glass transition of the complex heteropolysaccharides produced by the cyanobacteria. The molecular mobility at the glass transition, Tg, was affected by both the carboxymethylation treatment and the doping. The fragility index also decreased for the doped specimens, which may be attributed to an increase in the mobility of the polymer chains due to the plasticizing effect of the doping agents. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tailoring size and release kinetics of κ/ι-hybrid carrageenan microgels via a surfactant-assisted technique(Taylor & Francis, 2020-01-25)κ/ι-Hybrid carrageenan microgels were prepared to be used as drug delivery systems. A surfactant-assisted microemulsion technique was used. Tween® 80 was used as surfactant and enrofloxacin was used as a model drug. The results showed that the amount of surfactant used during processing determines the size of the microgels as well as the amount of enrofloxacin that can be loaded. At low surfactant content, the initial burst release effect is dominant whereas at high surfactant content the burst release effect is negligible and the Fickian diffusion mechanism is dominant. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Sustainable synthesis, reduction and applications of graphene obtained from renewable resources(Elsevier, 2021-09-01)Graphene is a revolutionary material with outstanding electrical, mechanical, thermal, and structural properties. The synthesis of graphene and its derivatives generally requires expensive and poisonous reagents. However, contemporary research efforts are switching towards more sustainable routes. The present review focused on the synthesis, performance, and applications of graphene-derived nanomaterials synthesized from waste biomass and reduced by green alternatives. Graphitization of waste carbon precursors is the most used method to obtain high purity graphite alternatives. Other methods, such as CVD, hydrothermal, laser, and CAS, have been investigated. Graphene yielded from biomass precursors exhibits properties similar to those from conventional sources. Green reduction of graphene oxide is carried out mostly by plant extracts from fruits, leaves, and other parts, which contain a high concentration of phenolic compounds. The as-prepared bio-waste and green-reduced graphene alternatives were applied in wastewater treatment, electrochemical storage devices, and metal ion sensors. In some cases, graphene showed significantly better performance than previous carbon-based nanomaterials reported in the literature. Despite being in its early stages of development, green-synthesized graphene has demonstrated great potential. As the interest in the development of sustainable alternatives continues to grow, future graphene research is expected to aim for this new line of research. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Hydrogel-based triboelectric nanogenerators: properties, performance, and applications(Wiley, 2021-12-23)The development of triboelectric nanogenerators (TENGs) in 2012 revolutionized the vision of environmental energy harvesting. Nowadays, TENG assembly, working mode, and material selection are investigated continuously in order to obtain high-performance and long-lasting devices. Hydrogels are flexible and stretchable water-swollen 3D polymer networks, which can be tailored to conduct electricity and render outstanding mechanical properties. Hydrogels have been used to develop novel flexible wearable TENGs. Here, we review the current knowledge concerning hydrogel-based TENGs, including an overview of relevant hydrogel characteristics, hydrogel-based TENG performance, and their practical applications. The single-electrode TENG working mode is the most popular in hydrogel-based TENGs as they can be easily attached and stretched for biomechanical energy harvesting. Hydrogel-based TENGs have demonstrated to be capable of delivering high electrical output (250-400 V, ≥10 μA) and being robust enough for devices that last for several months. Biomechanical energy sensing and harvesting, smart farming, biomedical, and human–machine control interfaces are investigated as potential applications of hydrogel-based TENGs. Interestingly, energy harvesting from human motion is of particular interest for this type of TENG due to its outstanding stretchability, strength, and additional physical properties, such as self-healing ability. In most cases, the devices are capable of powering small electronics entirely from harvested biomechanical energy. Biomedical applications involved wound healing acceleration driven by TENG-powered electrical stimuli and disease monitoring, including implantable devices. Despite showing promising electrical performance, controlling water evaporation is still challenging to maintain the mechanical and conductive properties of hydrogel-based TENGs. On the other hand, fully biodegradable TENGs are largely unexplored, as well as many applications, such as blue energy harvesting, the internet of things, and others. The next steps in this line of research must focus on addressing the main challenges of hydrogel-based TENGs and filling the application knowledge gaps. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, High-permittivity polymer–matrix composites for the development of triboelectric nanogenerators (TENGs) with enhanced performance: A review(Springer, 2024-08-01)In recent years, the rapid increase in low-power electronics has shifted research focus towards new energy-harvesting devices. Triboelectric energy-harvesting technologies, such as triboelectric nanogenerators (TENGs), offer an efficient way to convert mechanical energy into electrical energy through the triboelectric effect. Polymers are used to fabricate crucial components in TENGs, acting as the triboelectric layers and storing electric charge. The dielectric properties of these polymers significantly influence the energy conversion capabilities of TENGs. High-permittivity polymer-based composites and nanocomposites have been studied for energy storage, such as capacitors, supercapacitors, and solar cells among others. These high-permittivity polymer composites can also be used to develop novel TENGs with high output performance. This paper reviews the development of high-dielectric-permittivity polymeric composites to be used as active triboelectric surfaces for TENGs with enhanced output performance. One strategy involves incorporating inorganic materials, semiconductors, conductors, and carbon-derived materials as an active phase within the polymer matrix. Other strategies, including the usage of polymeric fillers, coating, polarization, and ion implantation techniques, are also reported. This review may serve as a reference for optimizing polymer-based dielectrics in energy-harvesting-related areas. Through a deeper understanding of these techniques and materials, we can enhance the performance of TENGs to achieve high output efficiency.1