Breve Introducción a la Física de los Materiales Poliméricos

Se presenta una introducción general a la física de los materiales poliméricos y a sus aplicaciones en el siglo XX

Dispersión de rayos X aplicado al análisis de nanotubos de carbono, polímeros y nanocompuestos

[EN] In this review we will show that wide and small angle X-ray scattering techniques (WAXS and SAXS respectively) can be a valuable tool to characterize the structure of carbon nanotubes (CNT) and related CNT-polymer nanocomposites at different characteristic length scales. Ranging from single carbon nanotubes to aggregates of CNTs X-ray scattering may offer structural information which can be crucial in order to design new materials based on carbon nanotubes.[ES] En este trabajo de revisión mostramos que las técnicas de dispersión de rayos X a alto y bajo ángulo (WAXS y SAXS respectivamente) pueden ser una herramienta muy valiosa para caracterizar la estructura de nanotubos de carbono (CNT) y nanocompuestos CNT-polímero, en diferentes escalas de longitud. La dispersión de rayos X puede ofrecer información estructural en el rango desde nanotubos de carbono aislados, hasta agregados de CNT. Dicha información puede ser crucial de cara a diseñar materiales basados en nanotubos de carbono.The authors thank the financial support from the MCYT (grant MAT2005-01768), Spain. The help of G. Broza, Z. Roslaniec, K. Schulte, I. Sics, B. H. Hsiao, S. S. Funari in different parts of this work is gratefully acknowledge. M. C. G.-G. and A. N. are also grateful to the Ramón y Cajal Program for the support of this reserach­.Peer reviewe

Laser-Induced Periodic Surface Structures on Conjugated Polymers: Poly(3-hexylthiophene)

8 pags.; 11 figs.© 2015 American Chemical Society. In this work, we report on the surface patterning of semiconducting poly(3-hexylthiophene) (P3HT) thin films by means of laser-induced periodic surface structures (LIPSS). Two different laser wavelengths, 266 and 532 nm, and a broad range of fluences and number of pulses have been used in order to optimize the LIPSS morphology. Ripples period and depth can be tuned by laser parameters. In particular, the high optical absorption of P3HT at 532 nm enables the formation of well-ordered nanostructures with periodicities around 460 nm. Near edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopy reveal a good chemical stability of P3HT thin films during LIPSS formation. Conducting atomic force microscopy (C-AFM) performed on the LIPSS reveals a higher electrical conduction in the trenches than in the ridge regions. Resonance Raman spectroscopy and grazing incidence wide-angle X-ray scattering (GIWAXS) indicate a loss of crystallinity of P3HT thin films during LIPSS formation, suggesting melting of the outer polymer surface. This effect produces ridges with molecular order lower than that of the original thin film. As a consequence of this transformation, the electrical conduction in the ridges becomes lower than that in the trenches.The authors gratefully acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (MINECO) through Projects MAT 2011-23455, MAT 2012-33517 and CTQ 2013-43086-P. A.R.-R. and E.R. are indebted to MINECO for a FPI (BES-2013-062620) and Ramon y Cajal (RYC-2011-08069) contracts, respectively. We thank the Swiss Light Source for beamtime at PolLux, where the NEXAFS experiments were performed. We also thank the ESRF for beamtime at BM26 where in situ GISAXS and GIWAXS experiments were carried out. We thank B. Watts for assistance in using beamline PolLux and G. Portale and W. Bras for beamline support at BM26. P. Müller-Buschbaum and S. Guo are thanked for seminal comments at the beginning of this workPeer Reviewe

In situ monitoring of laser-induced periodic surface structures formation on polymer films by grazing incidence small-angle X-ray scattering

9 pags.; 9 figs.© 2015 American Chemical Society. The formation of laser-induced periodic surface structures (LIPSS) on model spin-coated polymer films has been followed in situ by grazing incidence small-angle X-ray scattering (GISAXS) using synchrotron radiation. The samples were irradiated at different repetition rates ranging from 1 up to 10 Hz by using the fourth harmonic of a Nd:YAG laser (266 nm) with pulses of 8 ns. Simultaneously, GISAXS patterns were acquired during laser irradiation. The variation of both the GISAXS signal with the number of pulses and the LIPSS period with laser irradiation time is revealing key kinetic aspects of the nanostructure formation process. By considering LIPSS as one-dimensional paracrystalline lattice and using a correlation found between the paracrystalline disorder parameter, g, and the number of reflections observed in the GISAXS patterns, the variation of the structural order of LIPSS can be assessed. The role of the laser repetition rate in the nanostructure formation has been clarified. For high pulse repetition rates (i.e., 10 Hz), LIPSS evolve in time to reach the expected period matching the wavelength of the irradiating laser. For lower pulse repetition rates LIPSS formation is less effective, and the period of the ripples never reaches the wavelength value. Results support and provide information on the existence of a feedback mechanism for LIPSS formation in polymer films.The authors gratefully acknowledge financial support from the MINECO (MAT2011-23455, MAT2012-33517 and CTQ 2013-43086-P). E.R., I.M.-F., and A.R-R. also thank MINECO for a Ramon y Cajal contract (RYC-2011-08069) and FPI ́ fellowships (BES-2010-030074 and BES-2013-062620).Peer Reviewe

Laser Fabrication of Polymer Ferroelectric Nanostructures for Nonvolatile Organic Memory Devices

8 pags.; 5 figs.© 2015 American Chemical Society. Polymer ferroelectric laser-induced periodic surface structures (LIPSS) have been prepared on ferroelectric thin films of a poly(vinylidene fluoride-trifluoroethylene) copolymer. Although this copolymer does not absorb light at the laser wavelength, LIPSS on the copolymer can be obtained by forming a bilayer with other light-absorbing polymers. The ferroelectric nature of the structured bilayer was proven by piezoresponse force microscopy measurements. Ferroelectric hysteresis was found on both the bilayer and the laser-structured bilayer. We show that it is possible to write ferroelectric information at the nanoscale. The laser-structured ferroelectric bilayer showed an increase in the information storage density of an order of magnitude, in comparison to the original bilayer.The authors gratefully acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (MINECO), through Contract Nos. MAT 2011-23455, MAT 2012- 33517, and CTQ 2013-43086-P. D.E.M. thanks CSIC for the tenure of JAE-Pre fellowship and Fondo Social Europeo (FSE) for cofinancing the JAE Program. A.R.R. and E.R. thank MINECO for the tenure of a FPI contract (BES-2013-062620) and a Ramón y Cajal contract (No. RYC-2011-08069), respectively.Peer Reviewe

In situ real-time characterization of block copolymer self-assembly processes by GISAXS

E-MRS Spring Meeting and Exhibit will be held in the Convention Centre of Strasbourg (France), from June 18 to 22 (2018). .--https://www.european-mrs.com/block-copolymer-self-assembly-fundamentals-and-applications-emr

Inter and intra molecular dynamics in poly(trimethylene 2,5-furanoate) as revealed by infrared and Broadband Dielectric Spectroscopies

9 pags., 9 figs., 2 tabs.Infrared spectroscopy (IR) and Broadband Dielectric Spectroscopy (BDS) experiments have been performed in poly(trimethylene 2,5-furanoate)(PTF) and poly(trimethylene terephthalate)(PTT) below their glass transition temperatures. The BDS experiments reveal a richer inter-molecular dynamic for PTT as characterized by a multimodal β relaxation in contrast with the monomodal one exhibited by PTF. The evolution with temperature of comparable IR absorption bands is very similar for PTF and PTT and shows small shifts in wavenumbers towards lower values, with exception of the band related to the stretching mode of the carbonyl group. In addition, a significant difference appears in the shape of the bands associated with the –C[dbnd]O stretching. While for PTT the absorption feature is comprised of a single component, that for PTF exhibits several components suggesting the presence of hydrogen bonds. This effect may be responsible for the monomodal shape of the β relaxation of PTF since a higher degree of intramolecular coupling between the furan ring and the rest of the monomer is expected. Density Functional Theory (DFT) calculations support the experimental results revealing that as temperature increases an increment of the syn conformations of the 2,5-furandicarboxylic acid (FDCA) moiety is likely to occur in the amorphous state. The energy gain from more stable anti to less stable syn isomers can be compensated by the formation of hydrogen bonds between interchain FDCA moieties in syn conformations. This effect may cause additional hindrance to the intermolecular dynamics of the dielectric β relaxation. It is conceivable that the hindrance exhibited by PTF in both intra and inter-molecular dynamics may play a role in the reduction of gas diffusion and permeability of PTF in comparison with PTT.Grants PID2019-107514 GB-I00/AEI/10.13039/501100011033 and PID2019-106125 GB-I00/AEI/10.13039/501100011033 funded by MCIN/AEI/10.13039/501100011033 and by “ ERDF A way of making Europe”. GS acknowledges grant RYC2020-029810-I funded by MCIN/ AEI/10.13039/501100011033 and by “ ESF Investing in your future”. SP would like to thank for financial support from the National Science Centre within project SONATA no 2018/31/D/ST8/00792.

Is the sub-glass temperature relaxation of furan-based polymers related to their high gas barrier properties?

11th Conference on Broadband Dielectric Spectroscopy and its Applications (BDS2022), Donostia/San Sebastián, 04.Sep - 09.Sep 2022. -- Presentación con 25 diapositivasPoly(alkylene 2,5-furanoate)s, (PAF)s, are fully biobased homopolyesters based on 2,5-furandicarboxylic acid that have recently emerged as promising alternative to petroleum based poly(alkylene terephthalate)s. In addition to a lower production carbon footprint poly(alkylene 2,5-furanoate)s have received significant attention due to their outstanding gas barrier properties in comparison to traditional poly aromatic esters [1]. The influence of chain dynamics on barrier properties has also devoted some attention. Dielectric spectroscopy experiments performed in poly(trimethylene 2,5-furanoate) revealed that the subambient relaxation, below its glass transition temperature, exhibited an inhibition of the mode corresponding to the ester oxygen linked to the aliphatic subunit which efficiently relaxes in the poly(trimethylene terephthalate) counterpart [2]. Fourier Transform Infrared (FT-IR) spectroscopy can provide precise information of intra-molecular motions at the molecular level [3]. By evaluating the vibrational frequencies and the corresponding oscillator, strength from the IR spectra information about the intra-molecular dynamics can be available. In this study, we present a combined IR spectroscopy and BDS study focused on the sub-glass temperature molecular dynamics of poly(trimethylene 2,5-furanoate) in comparison to that of poly(trimethylene terephthalate) in order to shed light on the influence the dynamics on the barrier properties of Poly(alkylene 2,5-furanoate)s.The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Innovation (MICINN) through PID2019-107514GB-I00 / AEI / 10.13039/501100011033

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning