Biobased Acrylic Latexes/Sodium Carboxymethyl Cellulose Aqueous Binders for Lithium-Ion NMC 811 Cathodes.

The increasing demands for sustainable energy storage technologies have prompted extensive research in the development of eco-friendly materials for lithium-ion batteries (LIBs). This research article presents the design of biobased latexes, which are fluorine-free and rely on renewable resources, based on isobornyl methacrylate (IBOMA) and 2-octyl acrylate (2OA) to be used as binders in batteries. Three different compositions of latexes were investigated, varying the ratio of IBOMA and 2OA: (1) Poly2OA homopolymer, (2) Poly(2OA0,6-co-IBOMA0,4) random copolymer, and (3) PolyIBOMA homopolymer. The combination of the two monomers provided a balance between rigidity from the hard monomer (IBOMA) and flexibility from the soft one (2OA). The study evaluated the performance of the biobased latexes using sodium carboxymethyl cellulose (CMC) as a thickener and cobinder by fabricating LiNi0.8Mn0.1Co0.1O2 (NMC 811) cathodes. Also, to compare with the state of the art, organic processed PVDF electrodes were prepared. Among aqueous slurries, rheological analysis showed that the CMC + Poly(2OA0,6-co-IBOMA0,4) binder system resulted in the most stable and well-dispersed slurries. Also, the electrodes prepared with this latex demonstrated enhanced adhesion (210 ± 9 N m-1) and reduced cracks compared to other aqueous compositions. Electrochemical characterization revealed that the aqueous processed cathodes using the CMC + Poly(2OA0,6-co-IBOMA0,4) biobased latex displayed higher specific capacities than the control with no latex at high C-rates (100.3 ± 2.1 vs 64.5 ± 0.8 mAh g-1 at 5C) and increased capacity retention after 90 cycles at 0.5C (84% vs 81% for CMC with no latex). Overall, the findings of this study suggest that biobased latexes, specifically the CMC + Poly(2OA0,6-co-IBOMA0,4) composition, are promising as environmentally friendly binders for NMC 811 cathodes, contributing to the broader goal of achieving sustainable energy storage systems.

Polymer Colloids: Current Challenges, Emerging Applications, and New Developments.

Polymer colloids are complex materials that have the potential to be used in a vast array of applications. One of the main reasons for their continued growth in commercial use is the water-based emulsion polymerization process through which they are generally synthesized. This technique is not only highly efficient from an industrial point of view but also extremely versatile and permits the large-scale production of colloidal particles with controllable properties. In this perspective, we seek to highlight the central challenges in the synthesis and use of polymer colloids, with respect to both existing and emerging applications. We first address the challenges in the current production and application of polymer colloids, with a particular focus on the transition toward sustainable feedstocks and reduced environmental impact in their primary commercial applications. Later, we highlight the features that allow novel polymer colloids to be designed and applied in emerging application areas. Finally, we present recent approaches that have used the unique colloidal nature in unconventional processing techniques.

Single-Ion Conducting Polymer Nanoparticles as Functional Fillers for Solid Electrolytes in Lithium Metal Batteries.

Composite solid electrolytes including inorganic nanoparticles or nanofibers which improve the performance of polymer electrolytes due to their superior mechanical, ionic conductivity, or lithium transference number are actively being researched for applications in lithium metal batteries. However, inorganic nanoparticles present limitations such as tedious surface functionalization and agglomeration issues and poor homogeneity at high concentrations in polymer matrixes. In this work, we report on polymer nanoparticles with a lithium sulfonamide surface functionality (LiPNP) for application as electrolytes in lithium metal batteries. The particles are prepared by semibatch emulsion polymerization, an easily up-scalable technique. LiPNPs are used to prepare two different families of particle-reinforced solid electrolytes. When mixed with poly(ethylene oxide) and lithium bis(trifluoromethane)sulfonimide (LiTFSI/PEO), the particles invoke a significant stiffening effect (E' > 106 Pa vs 105 Pa at 80 °C) while the membranes retain high ionic conductivity (σ = 6.6 × 10-4 S cm-1). Preliminary testing in LiFePO4 lithium metal cells showed promising performance of the PEO nanocomposite electrolytes. By mixing the particles with propylene carbonate without any additional salt, we obtain true single-ion conducting gel electrolytes, as the lithium sulfonamide surface functionalities are the only sources of lithium ions in the system. The gel electrolytes are mechanically robust (up to G' = 106 Pa) and show ionic conductivity up to 10-4 S cm-1. Finally, the PC nanocomposite electrolytes were tested in symmetrical lithium cells. Our findings suggest that all-polymer nanoparticles could represent a new building block material for solid-state lithium metal battery applications.

Hospitalization trends and chronobiology for mental disorders in Spain from 2005 to 2015.

Rhythm research has had a long tradition in psychiatry, especially in affective disorders. The study of trends in incidence plays a central role in epidemiology and public health. The aims of this research were to describe the socio-demographic and clinical characteristics of persons admitted for psychiatric hospitalization and their trends and periodicity in cases (global and by groups) in Spain over the 11 year study span. We conducted a cross-sectional study of the hospital discharge database of Castilla y León from 2005 to 2015, selecting hospitalizations for psychiatric reasons. Trends in the rates of hospitalization were studied by joinpoint regression analysis. Time series analysis for periodicities was done by spectral analysis, fast Fourier transform, and cosinor analysis. Some 49501 hospitalizations due to psychiatric disorders, out of 2717192 hospital admissions, took place during the study span. Hospitalizations for psychosis were frequent (15949, 32.2%), while such for eating disorders were infrequent, but showed the highest average stay (28 days) and DRG relative weight (2.41). The general trend was a statistically significant 2% annual increase in psychiatric hospitalizations over the 11 year span; substance abuse was the only exception to this trend. The whole population and the subgroups of psychosis and bipolar disorders showed significant circannual (one-year) variation in admissions. The rhythm percentage of the global group was 11.4%, while the rhythm percentages of the psychosis, bipolar, and eating disorders were 17.1%, 17.5%, and 9.6%, respectively (p < .05).

Hospitalization and Socio-Health Care for Dementia in Spain.

Dementias are brain diseases that affect long-term cognitive and behavioral functions and cause a decrease in the ability to think and remember that is severe enough to disturb daily functioning. In Spain, the number of people suffering from dementia is rising due to population ageing. Reducing admissions, many of them avoidable, would be advantageous for patients and care-providers. Understanding the correlation of admission of people with dementia and its trends in hospitalization would help us to understand the factors leading to admission. We conducted a cross-sectional study of the hospital discharge database of Castilla y León from 2005 to 2015, selecting hospitalizations for dementia. Trends in hospitalizations by year and age quartiles were studied by joinpoint regression analysis. 2807 out of 2,717,192 total hospitalizations (0.10%) were due to dementias; the main groups were degenerative dementia (1907) followed by vascular dementia (607). Dementias are not a major cause of hospitalization, but the average stay and cost are high, and many of them seem avoidable. Decreasing trends were detected in hospitalization rates for all dementias except for the group of mild cognitive impairment, which grew. An increasing-decreasing joinpoint detected in 2007 for vascular dementia and the general downward hospitalization trends for most dementias suggest that socio-health measures established since 2007 in Spain might play a key role in reducing hospitalizations.

Phase Separation Driven On-Demand Debondable Waterborne Pressure-Sensitive Adhesives.

A waterborne pressure-sensitive adhesive (PSA) that shows high adhesive performance and easy debondability on demand without leaving residues on the substrate (adhesive failure) has been developed. A key component of the PSA is a semicrystalline phase that is beneficial for the adhesive properties and that becomes fluid when heated above the melting temperature. Migration of this liquid-like polymer to the substrate-adhesive interface and hardening upon cooling results in a hard non-tacky interface that facilitates debonding. The effect of the particle morphology on the debonding ability is discussed.

New Class of Alkoxyamines for Efficient Controlled Homopolymerization of Methacrylates.

Despite significant efforts, the design of alkoxyamines for polymerization of methacrylic monomers in a well-controlled fashion with good retention of the active chain ends remains a challenge. Herein, the facile synthesis of several alkoxyamines, which are capable of achieving this long sought-after goal, is reported. Controlled homopolymerization of methyl methacrylate is achieved as determined by a linear increase in molecular weight with conversion and first-order rate plots for various alkoxyamine concentrations. The versatility of the alkoxyamines is further exemplified by the ability to control the homopolymerization of styrene and by synthesis of a block copolymer of a second methacrylate in an efficient chain extension process.

From polymer latexes to multifunctional liquid marbles.

A simple method to prepare multifunctional liquid marbles and dry water with magnetic, color, and fluorescent properties is presented. Multifunctional liquid marbles were prepared by encapsulation of water droplets using flocculated polymer latexes. First, the emulsion polymerization reaction of polystyrene and poly(benzyl methacrylate) was carried out using cheap and commercially available cationic surfactants. Subsequently, flocculation of the latex was provoked by an anion-exchange reaction of the cationic surfactant by the addition of lithium bis(trifluoromethanesulfonyl)imide salt. The flocculated polymer latex was filtered and dried, leading to very hydrophobic micronanoparticulated powders. These powders showed a great ability to stabilize the air/water interface. Stable liquid marbles were obtained by rolling water droplets onto the hydrophobic powders previously prepared. The use of very small polystyrene nanoparticles led us to the preparation of very stable and the biggest known liquid marbles up to 2.5 mL of water. Furthermore, the introduction of fluorescent comonomer dyes into the polymer powders allowed us to obtain new morphological images and new knowledge about the structure of liquid marbles by confocal microscopy. Furthermore, the introduction of magnetic nanoparticles into the polymer latex led to magnetic responsive liquid marbles, where the iron oxide nanoparticles are protected within a polymer. Altogether this method represents an accessible and general platform for the preparation of multifunctional liquid marbles and dry water, which may contribute to extending of their actual range of applications.

Encapsulation of clay within polymer particles in a high-solids content aqueous dispersion.

By using a two-step polymerization process, it was possible to encapsulate clay platelets within polymer particles dispersed in water. First, seed polymer particles with chemically bonded clay were obtained by batch miniemulsion polymerization. Then, the clay was buried within the particles by the addition of neat monomer in a second step. The final stable dispersions can have a solids content of up to 50 wt %. Transmission electron microscopy images clearly show the presence of clay platelets inside the polymer colloids, although they are not totally exfoliated. The obtained nanocomposites showed an increase in both the storage modulus in the rubbery state and the water resistance as the clay content increases. The approach presented here might be useful for encapsulating other high-aspect ratio nanofillers.

Surfactant-free miniemulsion polymerization of n-BA/S stabilized by NaMMT: films with improved water resistance.

The use of sodium montmorillonite clay as a stabilizer in the surfactant-free emulsion polymerization of n-butyl acrylate/styrene (n-BA/S) was assessed. It was shown that the use of the clay alone did not yield the desired armored latex particles. A functional comonomer, that is, a phosphate ester of poly(ethylene glycol) monomethacrylate, was used to improve the interaction between the polymer and clay, thus allowing for the clay platelets to adhere to the surface of the polymer particles. The morphology of the films obtained for these two different scenarios was similar and resembled a honeycomb structure. However, their water-resistance properties differed drastically. The water absorption and water vapor permeation rate were much lower in the hybrid n-BA/S/clay films in the presence of the functional monomer than in the films obtained without the functional monomer.

Modeling the equilibrium morphology of nanodroplets in the presence of nanofillers.

Waterborne polymer nanocomposites containing carbon nanotubes, clay platelets, laponite disks and other spherical/nonspherical nanofillers have been the focus of many recent investigations. The miniemulsion polymerization has proved to be a powerful technique to create new hybrid waterborne nanocomposites with enhanced properties. It is necessary to understand how the nanofiller shape/size and its compatibility with the phases affects the equilibrium morphology of the polymer nanoparticle to control the morphology and the properties of the resulting polymeric dispersions. With the aid of Monte Carlo simulations, the equilibrium morphology of hybrid monomer nanodroplets in the presence of nanofillers with different characteristics was obtained. A series of morphology maps depending on the nanofiller compatibility with the monomer and water phases and its shape have been obtained. These new maps may help to design and determine the required conditions to synthesize innovative waterborne polymer nanocomposites with specific morphologies through miniemulsion polymerization.

New agitated and thermostatized cell for in situ monitoring of fast reactions by synchrotron SAXS.

A thermostatized and agitated sample cell for synchrotron small-angle X-ray scattering (SAXS) measurements of liquid samples (homogeneous or heterogeneous) has been developed. The cell is composed of a compact main body with inlet and outlet windows for the beams of light. The volume of the cell is approximately 0.8 ml and the distance between the windows is 5 mm to allow accurate SAXS measurements. The cell is thermostatized by means of a jacket that surrounds the sample holder and it is connected to a thermostatic bath. In addition, the cell has a top and a bottom lid that allow easy cleaning and maintenance without demounting the optical windows. The cell has been used to run SAXS measurements of liquid samples and, for the first time, a mini-emulsion polymerization reaction has been monitored by SAXS.

Melatonin rhythm in children with enuresis.

OBJECTIVE: To study the circadian rhythm of melatonin in children with enuresis. PATIENTS AND METHODS: Twenty-five children, divided into two groups (enuretic patients and controls) were assessed; salivary samples were collected to measure melatonin by radioimmunoassay using commercial kits. Friedman two-way anova and Wilcoxon tests were used to assess the circadian rhythm of melatonin, and anova with between-patient factors and Mann-Whitney tests to compare melatonin values and groups. RESULTS: Both groups had statistically significant differences in melatonin concentration during the 24-h period (both P < 0.001), with a circadian rhythm; the highest values were always at approximately 04.00 hours. There were no significant differences overall in melatonin values between cases and controls, but patients had lower peak values than controls at 04.00 hours, and higher melatonin levels at 24.00 hours, but with no significant differences. CONCLUSION: There was some evidence for minor disturbances in the circadian rhythm of melatonin as a cause of enuresis, but the rhythm was not grossly disrupted.

Monitoring of high solids content starved-semi-batch emulsion copolymerization reactions by Fourier transform Raman spectroscopy.

A high solids content n-butyl acrylate/methyl methacrylate emulsion copolymerization process carried out under starved semi-batch conditions was for the first time monitored on-line by means of Fourier transform (FT)-Raman spectroscopy. Partial least squares regression was employed to build calibration models that allowed relating the spectra with solids content (overall conversion), free amounts of both n-butyl acrylate (n-BA) and methyl methacrylate (MMA), and cumulative copolymer composition. In spite of the heterogeneous nature of the polymerization, the similarities of the spectra for MMA, n-BA, and for the copolymer, and the low monomer concentrations in the reactor, the FT-Raman spectroscopy has been shown to be a suitable noninvasive sensor to accurately monitor the process. Therefore, it is well suited for on-line control of all-acrylic polymerization systems.

Monitoring of emulsion polymerization reactors by Raman spectroscopy: calibration model maintenance.

Fourier transform (FT)-Raman combined with partial least squares regression (PLS-R) calibration models allows the accurate monitoring of solids content, copolymer composition, and free amounts of monomers in starved semi-batch emulsion copolymerizations. The calibration models remain valid as long as the spectrometer and the measuring conditions are unchanged. Unfortunately, maintenance and/or repairing of the spectrometer result in changes in the relative intensities of the peaks of the Raman spectrum, reducing the performance of the calibration models. Therefore, a strategy for the up-date of the PLS-R calibration models is needed. Strategies for calibration model maintenance were assessed, and we found that the best strategy was to build a new model composed of the old PLS-R model plus a PLS-R model able to account for the model mismatch of the old model.

[Cardiovascular risk factors in the circadian rhythm of acute myocardial infarction]. / Factores de riesgo cardiovascular en el ritmo circadiano del infarto agudo de miocardio.

INTRODUCTION AND OBJECTIVES: The aim of this study was to analyze the influence of modifiable cardiovascular risk factors on the circadian rhythm of acute myocardial infarction. PATIENTS AND METHOD: We analyzed a retrospective cohort of 54,249 patients from a multicenter study of acute myocardial infarction (the Spanish ARIAM study). The variables were time of onset of symptoms, age, sex, previous ischemic heart disease, coronary unit discharge status, previous stroke, familial antecedents of ischemic heart disease, hypertension, diabetes, dyslipidemia, smoking, and reinfarction. To verify the presence of circadian rhythm, we developed a simple test of equality of time series based on cosinor analysis of multiple sinusoid curves. Three sinusoids (24, 12 and 8 hour periods) were used. RESULTS: The time of onset of pain showed a circadian rhythm (P< .01), with a peak at 10:07 am and a trough at 4:46 am. All subgroups categorized according to the presence of the variables analyzed here showed a circadian rhythm, with a sinusoid curve after adjustment. In patients with diabetes or reinfarction or who were smokers, the sinusoid curve was bimodal. CONCLUSIONS: Time of onset of symptoms in patients with acute myocardial infarction follows a circadian rhythm. Diabetes, smoking and reinfarction can modify the standard circadian rhythm of onset of myocardial infarction.