Tailoring bombyx mori silk as multifuctional material for advanced applications.

288 p.Materials support human development. Among the available materials, polymers are nowadays essential and practically omnipresent because of their unrivalled properties. Unfortunately, polymers are synthesized from oil, and they tend to accumulate in nature, which represents a serious environmental impact.To minimize these damages, materials science suggests replacing synthetic polymers with bio-based materials. To promote the use of these more sustainable materials, the objective of the work has been to demonstrate the real applicability of bio-based materials, and more specifically Silk Fibroin (SF), a protein obtained from Bombyx mori (silkworm) cocoons. This protein displays unique physical-chemical properties that make it an interesting substrate for the development of new materials with advanced properties.Two main fields of application have been selected in this work for SF: i) electronics (active composites for sensors and actuators) and ii) porous structures for biomedicine, energy, and environment.For electronics, SF has been combined with i) carbon nanotubes (CNT) to obtain force sensors with piezoresistive responses (PR) of ~ 4 MPa-1 at pressures of 0.11 MPa; ii) with silver nanowires (SNW) to obtain PR of 26 GPa-1 when the pressure is between 0.2 and 0.4 MPa. Also, SF/SNW nanocomposites show optical transparency at SNW loads above 3%; iii) with cobalt ferrite nanoparticles (CFO) to obtain magnetic actuators with a magnetization value of ~ 10 emu·g¿1 and coercivity of almost 4 kOe, (20 wt. % CFO); and iv) with ionic liquids (IL) to obtain bending actuators with bending responses of ~ 0.5 by applying low voltages (3-5 V).SF has been processed also for the development of porous structures by i) electrospinning, to obtain scaffolds that when are combined with CFO particles, stimulate the bone cells development; ii) by salt leaching; to obtain Li-ion battery separators that lead to battery performance of 89,3 y 131,3 mAh·g¿1, for 2C and C/8 cycles respectively and iii) by gas foaming, gelation and freeze-drying, to obtain samples with porosity values above 94% and aqueous Cr adsorption capacities up to 3 mg/g.Bc Materials: Basque Center for materials applications & nanostructure

Tailoring bombyx mori silk as multifuctional material for advanced applications.

288 p.Materials support human development. Among the available materials, polymers are nowadays essential and practically omnipresent because of their unrivalled properties. Unfortunately, polymers are synthesized from oil, and they tend to accumulate in nature, which represents a serious environmental impact.To minimize these damages, materials science suggests replacing synthetic polymers with bio-based materials. To promote the use of these more sustainable materials, the objective of the work has been to demonstrate the real applicability of bio-based materials, and more specifically Silk Fibroin (SF), a protein obtained from Bombyx mori (silkworm) cocoons. This protein displays unique physical-chemical properties that make it an interesting substrate for the development of new materials with advanced properties.Two main fields of application have been selected in this work for SF: i) electronics (active composites for sensors and actuators) and ii) porous structures for biomedicine, energy, and environment.For electronics, SF has been combined with i) carbon nanotubes (CNT) to obtain force sensors with piezoresistive responses (PR) of ~ 4 MPa-1 at pressures of 0.11 MPa; ii) with silver nanowires (SNW) to obtain PR of 26 GPa-1 when the pressure is between 0.2 and 0.4 MPa. Also, SF/SNW nanocomposites show optical transparency at SNW loads above 3%; iii) with cobalt ferrite nanoparticles (CFO) to obtain magnetic actuators with a magnetization value of ~ 10 emu·g¿1 and coercivity of almost 4 kOe, (20 wt. % CFO); and iv) with ionic liquids (IL) to obtain bending actuators with bending responses of ~ 0.5 by applying low voltages (3-5 V).SF has been processed also for the development of porous structures by i) electrospinning, to obtain scaffolds that when are combined with CFO particles, stimulate the bone cells development; ii) by salt leaching; to obtain Li-ion battery separators that lead to battery performance of 89,3 y 131,3 mAh·g¿1, for 2C and C/8 cycles respectively and iii) by gas foaming, gelation and freeze-drying, to obtain samples with porosity values above 94% and aqueous Cr adsorption capacities up to 3 mg/g.Bc Materials: Basque Center for materials applications & nanostructure

Modulation of the Bifunctional CrVI to CrIII Photoreduction and Adsorption Capacity in ZrIV and TiIV Benchmark Metal-Organic Frameworks

The presence of hexavalent chromium water pollution is a growing global concern. Among the currently applied technologies to remove CrVI, its adsorption and photocatalytic reduction to CrIII less mobile and toxic forms are the most appealing because of their simplicity, reusability, and low energy consumption. However, little attention has been paid to bifunctional catalysts, that is, materials that can reduce CrVI to CrIII and retain both hexavalent and trivalent chromium species at the same time. In this work, the dual CrVI adsorption–reduction capacity of two iconic photoactive water-stable zirconium and titanium-based metal–organic frameworks (MOFs) has been investigated: UiO-66-NH2 and MIL-125. The bifunctionality of photoactive MOFs depends on different parameters, such as the particle size in MIL-125 or organic linker functionalization/defective positions in UiO-66 type sorbents. For instance, the presence of organic linker defects in UiO-66 has shown to be detrimental for the chromium photoreduction but beneficial for the retention of the CrIII phototransformed species. Both compounds are able to retain from 90 to 98% of the initial chromium present at acidic solutions as well as immobilize the reduced CrIII species, demonstrating the suitability of the materials for CrVI environmental remediation. In addition, it has been demonstrated that adsorption can be carried out also in a continuous flux mode through a diluted photoactive MOF/sand chromatographic column. The obtained results open the perspective to assess the bifunctional sorption and photoreduction ability of a plethora of MOF materials that have been applied for chromium capture and photoreduction purposes. In parallel, this work opens the perspective to develop specific chemical encoding strategies within MOFs to transfer this bifunctionality to other related water remediation applications.The authors thank the financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through projects MAT2016-76739-R (AEI/FEDER, EU) and MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including FEDER financial support) and from the Basque Government Industry and Education Departments under the ELKARTEK (LION, ACTIMAT), HAZITEK (SIMAN) and PIBA (PIBA-2018-06) programs, respectively. The European Commission Research & Innovation H2020-MSCA-RISE-2017 (Ref.: 778412) INDESMOF project