Nuevos materiales poliméricos nanoestructurados

Presentaciones de la Decimotercera Jornada de Materiales de la Universidad Carlos III de Madrid celebrada el 31 de marzo de 2011 en Leganés, MadridNo publicad

Hydrothermal-Freeze-Casting of Poly(amidoamine)-Modified Graphene Aerogels towards CO2 Adsorption

[EN] This article presents novel poly(amidoamine) (PAMAM) dendrimer-modified with partially-reduced graphene oxide (rGO) aerogels, obtained using the combined solvothermal synthesis-freeze-casting approach. The properties of modified aerogels are investigated with varying synthesis conditions, such as dendrimer generation (G), GO:PAMAM wt. ratio, solvothermal temperature, and freeze-casting rate. Scanning electron microscopy, Fourier Transform Infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy are employed to characterize the aerogels. The results indicate a strong correlation of the synthesis conditions with N content, N/C ratio, and nitrogen contributions in the modified aerogels. Our results show that the best CO2 adsorption performance was exhibited by the aerogels modified with higher generation (G7) dendrimer at low GO:PAMAM ratio as 2:0.1 mg mL(-1) and obtained at higher solvothermal temperature and freeze-casting in liquid nitrogen. The enclosed results are indicative of a viable approach to modify graphene aerogels towards improving the CO2 capture.This research was supported by European Commission through the GRAMOFON project, contract No. H2020-LCE-24-2016-727619.Pruna, AI.; Cárcel, AC.; Benedito, A.; Giménez Torres, E. (2021). Hydrothermal-Freeze-Casting of Poly(amidoamine)-Modified Graphene Aerogels towards CO2 Adsorption. International Journal of Molecular Sciences. 22(17):1-15. https://doi.org/10.3390/ijms22179333115221

Comparative study between the microwave heating efficiency of carbon nanotubes versus multilayer graphene in polypropylene nanocomposites

Multiwall carbon nanotubes (MWCNT) and multilayer graphene (MLG) were studied as microwave susceptor additives for polymers. Different percentages of both nanoparticles were added to polypropylene by melt compounding in order to study the microwave absorption and the polymer heating. Polypropylene was selected as polymer matrix due to its unpolar nature to avoid the influence of polymer polarity and evaluate the influence of the nanoparticles. Electrochemical spectroscopy impedance measurements were carried out to evaluate the conductive and dielectric properties of nano composites. Results showed that nanocomposites with higher electrical conductivity have better capacity of absorbing microwave radiation. High values of permittivity and loss tangent also increases the microwave radiation absorption and the ability of the material to convert this electromagnetic radiation into heat. Carbon nanotubes showed better microwave susceptor behavior than graphene multilayer. Nanocomposites with 1% w/w of carbon nanotubes can be compared with the heating efficiency of a polypropylene filled with 10% w/w of multilayer graphene. The higher efficiency of carbon nanotubes it is explained by their higher electrical conductivity and optimal dielectric properties of the nanocomposites compared to multilayer graphene polymer systems.Galindo-Galiana, B.; Benedito, A.; Giménez Torres, E.; Compañ Moreno, V. (2016). Comparative study between the microwave heating efficiency of carbon nanotubes versus multilayer graphene in polypropylene nanocomposites. Composites Part B: Engineering. 98:330-338. doi:10.1016/j.compositesb.2016.04.082S3303389

Electrospinning of biodegradable polylactide/hydroxyapatite nanofibers: Study on the morphology, crystallinity structure and thermal stability

[EN] Aligned mats of poly(lactic acid) (PLA) nanofibers containing nanosized hydroxyapatite filler have been obtained via electrospinning onto a rotating mandrel. Their structure and morphology have been characterized as a function of the production parameters, by SEM, DSC, DMA and WAXS, with emphasis in the effects of the take-up velocity. SEM, DSC and X-ray diffraction studies confirmed a reduction in fiber diameter, an increase of fiber orientation and a highly crystalline structure of the mats collected at higher speed due to the stretching produced during the process. Double melting behavior was observed, suggesting the presence of two crystalline forms. Moreover the higher storage modulus (E¿ modulus), and glass transition temperatures of the higher speed collected mats were correlated with an enhancement in the thermal stability and nanofiller distribution. © 2012 Elsevier Ltd. All rights reserved.This project has been supported by Project MAT2010/21494-C03 of Spanish Ministry for Science and Innovation (MICINN). AS acknowledges the support of FPU grant from MED (MED-FPU; AP2009-2482).Sonseca Olalla, A.; Peponi, L.; Sahuquillo, O.; Kenny, J.; Giménez Torres, E. (2012). Electrospinning of biodegradable polylactide/hydroxyapatite nanofibers: Study on the morphology, crystallinity structure and thermal stability. Polymer Degradation and Stability. 97(10):2052-2059. https://doi.org/10.1016/j.polymdegradstab.2012.05.009S20522059971

Ionic Liquid Composite Polybenzimidazol Membranes for High Temperature PEMFC Applications

[EN] A series of proton exchange membranes based on polybenzimidazole (PBI) were prepared using the low cost ionic liquids (ILs) derived from 1-butyl-3-methylimidazolium (BMIM) bearing different anions as conductive fillers in the polymeric matrix with the aim of enhancing the proton conductivity of PBI membranes. The composite membranes prepared by casting method (containing 5 wt. % of IL) exhibited good thermal, dimensional, mechanical, and oxidative stability for fuel cell applications. The effects of anion, temperature on the proton conductivity of phosphoric acid-doped membranes were systematically investigated by electrochemical impedance spectroscopy. The PBI composite membranes containing 1-butyl-3-methylimidazolium-derived ionic liquids exhibited high proton conductivity of 0.098 Scm(-1) at 120 degrees C when tetrafluoroborate anion was present in the polymeric matrix. This conductivity enhancement might be attributed to the formed hydrogen-bond networks between the IL molecules and the phosphoric acid molecules distributed along the polymeric matrix.The authors acknowledge the Spanish Ministerio de Economia y Competitividad (MINECO) for the financial support under the project ENE/2015-69203-R.Escorihuela, J.; Garcia Bernabe, A.; Montero Reguera, ÁE.; Sahuquillo, O.; Giménez Torres, E.; Compañ Moreno, V. (2019). Ionic Liquid Composite Polybenzimidazol Membranes for High Temperature PEMFC Applications. Polymers. 11(4):1-14. https://doi.org/10.3390/polym1104073211411

Tailoring the Performance of Graphene Aerogels for Oil/Organic Solvent Separation by 1-Step Solvothermal Approach

[EN] Ultra-light eco-friendly graphene oxide (GO)-based aerogels are reported by simple one-step solvothermal self-assembly. The effect of varying parameters such as C/O ratio of GO; reducing agent amount; temperature; and duration on the properties of the aerogels was studied. The structural and vibrational features and hydrophobic surface properties of the obtained aerogels were obtained by XRD; FTIR; XPS; Raman; SEM; and contact angle measurements. The effect of synthesis conditions on the engine oil and organic solvent absorption properties was assessed. The results indicated that the lower the C/O ratio of GO, the better the absorption properties, with the best performance for oil uptake reaching 86 g g(-1). The obtained results indicate the approach based on ice-templating and the tailoring of oxygen content in GO make the resulting aerogels potential candidates for use in oil spill and organic solvent treatments.This research was supported by European Commission through GRAMOFON project, contract No. H2020-LCE-24-2016-727619.Pruna, AI.; Cárcel, AC.; Barjola, A.; Benedito, A.; Giménez Torres, E. (2019). Tailoring the Performance of Graphene Aerogels for Oil/Organic Solvent Separation by 1-Step Solvothermal Approach. Nanomaterials. 9(8):1-11. https://doi.org/10.3390/nano90810771119

AgBTC MOF-Mediated Approach to Synthesize Silver Nanoparticles Decorated on Reduced Graphene Oxide (rGO@Ag) for Energy Storage Applications

[EN] Nanowires of silver-based metal-organic framework (MOF) (AgBTC, BTC = 1,3,5-benzenetricarboxylate) were grown onto graphene oxide layers to generate GO-AgBTC nano composites. Thermal treatment of these composites in inert atmosphere produced reduced graphene oxide (rGO) decorated with well-dispersed and homogeneous silver nanoparticles (rGO@ Ag). The easy and scalable synthesis of AgNPs via MOF-mediated synthesis was achieved by the thermal decomposition of the AgBTC directly onto the rGO surface. The structure, morphology, and electrochemical properties of this novel material were investigated by XRD, Raman, TGA, FE-SEM, TEM, cyclic voltammetry, and galvanostatic charge and discharge experimental techniques. The results showed improved capacitive features for rGO@Ag. Specific gravimetric capacitance measured by galvanostatic charge- discharge yielded a value of 151.97 F/g at the current density of 0.5 A/g, pointing out that MOF-mediated synthesis offers a facile method to generate rGO electrodes decorated by uniformly distributed nanoparticles for energy storage devices.The authors are grateful for Grant PID2020-112590GB-C21 funded by MCIN/AEI/10.13039/501100011033.Barjola, A.; Rapeyko, A.; Sahuquillo, O.; Llabrés I Xamena, FX.; Giménez Torres, E. (2023). AgBTC MOF-Mediated Approach to Synthesize Silver Nanoparticles Decorated on Reduced Graphene Oxide (rGO@Ag) for Energy Storage Applications. ACS Applied Energy Materials. 6(18):9159-9169. https://doi.org/10.1021/acsaem.2c038729159916961

Proton Conductivity through Polybenzimidazole Composite Membranes Containing Silica Nanofiber Mats

[EN] The quest for sustainable and more efficient energy-converting devices has been the focus of researchers 0 efforts in the past decades. In this study, SiO2 nanofiber mats were fabricated through an electrospinning process and later functionalized using silane chemistry to introduce different polar groups OH (neutral), SO3H (acidic) and NH2 (basic). The modified nanofiber mats were embedded in PBI to fabricate mixed matrix membranes. The incorporation of these nanofiber mats in the PBI matrix showed an improvement in the chemical and thermal stability of the composite membranes. Proton conduction measurements show that PBI composite membranes containing nanofiber mats with basic groups showed higher proton conductivities, reaching values as high as 4 mS.cm(-1) at 200 degrees C.This research was funded by the Spanish Ministerio de Economia y Competitividad (MINECO) for the financial support, grant number ENE/2015-69203-R.Escorihuela, J.; Garcia Bernabe, A.; Montero Reguera, ÁE.; Andrio, A.; Sahuquillo, O.; Giménez Torres, E.; Compañ Moreno, V. (2019). Proton Conductivity through Polybenzimidazole Composite Membranes Containing Silica Nanofiber Mats. Polymers. 11(7):1-16. https://doi.org/10.3390/polym1107118211611

Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin

[EN] Efforts to fabricate low-power up converting solid-state systems have rapidly increased in the past decade because of their possible application in several fields such as bio-imaging, drug delivery, solar harvesting or displays. The synthesis of upconverting cross-linked polyester rubbers with covalently tethered chromophores is presented here. Cross-linked films were prepared by reacting a poly(mannitol- sebacate) pre-polymer with 9,10-bis(4-hydroxymethylphenyl) anthracene (DPA-(CH2OH)2) and palladium mesoporphyrin IX. These chromophores served as emitters and sensitizers, respectively, and through a cascade of photophysical events, resulted in an anti-Stokes shifted emission. Indeed, blue emission (*440 nm) of these solid materials was detected upon excitation at 543 nm with a green laser and the power dependence of integrated unconverted intensity versus excitation was examined. The new materials display upconversion at power densities as low as 32 mW/cm2, and do not display phase de-mixing, which has been identified as an obstacle in rubbery blends comprising untethered chromophores.The authors are thankful for the financial support of the Swiss National Science Foundation (200021_13540/1 and 200020_152968), Spanish Ministry of Economy and Competitiveness (Project MAT2010/21494-C03) and the Adolphe Merkle Foundation. The authors thank Prof. Christoph Weder for his help and support.Lee, S.; Sonseca, A.; Vadrucci, R.; Giménez Torres, E.; Foster, E.; Simon, YC. (2014). Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin. Journal of Inorganic and Organometallic Polymers. 24(5):898-903. https://doi.org/10.1007/s10904-014-0063-7S898903245C. A. Parker, C. G. Hatchard. P. Chem. Soc. London, 386–387 (1962)Y.C. Simon, C. Weder, J. Mater. Chem. 22, 20817–20830 (2012)J.Z. Zhao, S.M. Ji, H.M. 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Multiwalled carbon nanotubes incorporated into a miscible blend of poly(phenylenether)/polystyrene- Processing and characterization

[EN] 4 wt% multiwalled carbon nanotubes (MWCNTs) were incorporated into a miscible blend of polyphenylenether/ polystyrene (PPE/PS) on a twin-screw extruder at a screw speed of 600 rpm. The masterbatch obtained was diluted at 400 and 600 rpm to obtain lower MWCNT loadings in PPE/PS. Electron microscopy & optical microscopy images show very good MWCNT dispersion even at high filler loadings of 4 wt%, but slightly larger agglomerate size fractions are observable at higher screw speeds. While MWCNT addition enhanced the thermal stability of PPE/PS, a small change in glass transition was observed on the composites at different filler concentrations compared to PPE/PS. The specific heat capacity at glass transition decreases considerably until 2 wt% MWCNT and levels down thereafter for both processing conditions pointing to enhanced filler-matrix interaction at lower loadings. Storage modulus of the nanocomposites was enhanced significantly on MWCNT incorporation with reinforcing effect dropping considerably as a function of temperature, especially at lower filler contents. The modulus and the tensile strength of PPE/PS were only marginally enhanced in spite of excellent MWCNT dispersion in the matrix. Electrical percolation occurs at 0.4 wt% MWCNT content, and the electrical conductivity of 0.5 wt% MWCNT reinforced PPE/PS was close to 12 orders in magnitude higher compared to PPE/PS.The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7-PEOPLE-ITN-2008) under grant agreement number 238363.Sathyanarayana, S.; Wegrzyn, M.; Olowojoba, G.; Benedito, A.; Giménez Torres, E.; Hübner, C.; Henning, F. (2013). Multiwalled carbon nanotubes incorporated into a miscible blend of poly(phenylenether)/polystyrene- Processing and characterization. eXPRESS Polymer Letters. 7(7):621-635. https://doi.org/10.3144/expresspolymlett.2013.59S6216357