Polymat

This paper focuses on the linguistic landscape of two streets in two multilingual cities in Friesland (Netherlands) and the Basque Country (Spain) where a minority language is spoken, Basque or Frisian. The paper analyses the use of the minority language (Basque or Frisian), the state language (Spanish or Dutch) and English as an international language on language signs. It compares the use of these languages as related to the differences in language policy regarding the minority language in these two settings and to the spread of English in Europe. The data include over 975 pictures of language signs that were analysed so as to determine the number of languages used, the languages on the signs and the characteristics of bilingual and multilingual signs. The findings indicate that the linguistic landscape is related to the official language policy regarding minority languages and that there are important differences between the two settings.

Improved stability and efficiency of two-terminal monolithic perovskite-silicon tandem solar cells will require reductions in recombination losses. By combining a triple-halide perovskite (1.68 electron volt bandgap) with a piperazinium iodide interfacial modification, we improved the band alignment, reduced nonradiative recombination losses, and enhanced charge extraction at the electron-selective contact. Solar cells showed open-circuit voltages of up to 1.28 volts in p-i-n single junctions and 2.00 volts in perovskite-silicon tandem solar cells. The tandem cells achieve certified power conversion efficiencies of up to 32.5%.

A novel plastic with useful properties can easily be recycled again and again

Plastics have become indispensable in modern life and the material of choice in packaging applications, but they have also caused increasing plastic waste accumulation in oceans and landfills. Although there have been continuous efforts to develop biodegradable plastics, the mechanical and/or transport properties of these materials still need to be significantly improved to be suitable for replacing conventional plastic packaging materials. Here we report a class of biorenewable and degradable plastics, based on copolymers of γ-butyrolactone and its ring-fused derivative, with competitive permeability and elongation at break compared to commodity polymers and superior mechanical and transport properties to those of most promising biobased plastics. Importantly, these materials are designed with full chemical recyclability built into their performance with desired mechanical and barrier properties, thus representing a circular economy approach to plastic packaging materials.

Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels.

Electrolytes based on organic solvents used in current Li-ion batteries are not compatible with the next-generation energy storage technologies including those based on Li metal. Thus, there has been an increase in research activities investigating solid-state electrolytes, ionic liquids (ILs), polymers, and combinations of these. This Account will discuss some of the work from our teams in these areas. Similarly, other metal-based technologies including Na, Mg, Zn, and Al, for example, are being considered as alternatives to Li-based energy storage. However, the materials research required to effectively enable these alkali metal based energy storage applications is still in its relative infancy. Once again, electrolytes play a significant role in enabling these devices, and research has for the most part progressed along similar lines to that in advanced lithium technologies. Some of our recent contributions in these areas will also be discussed, along with our perspective on future directions in this field. For example, one approach has been to develop single-ion conductors, where the anion is tethered to the polymer backbone, and the dominant charge conductor is the lithium or sodium countercation. Typically, these present with low conductivity, whereas by using a copolymer approach or incorporating bulky quaternary ammonium co-cations, the effective charge separation is increased thus leading to higher conductivities and greater mobility of the alkali metal cation. This has been demonstrated both experimentally and via computer simulations. Further enhancements in ion transport may be possible in the future by designing and tethering more weakly associating anions to the polymer backbone. The second approach considers ion gels or composite polymer electrolytes where a polymerized ionic liquid is the matrix that provides both mechanical robustness and ion conducting pathways. The block copolymer approach is also demonstrated, in this case, to simultaneously provide mechanical properties and high ionic conductivity when used in combination with ionic-liquid electrolytes. The ultimate electrolyte material that will enable all high-performance solid-state batteries will have ion transport decoupled from the mechanical properties. While inorganic conductors can achieve this, their rigid, brittle nature creates difficulties. On the other hand, ionic polymers and their composites provide a rich area of chemistry to design and tune high ionic conductivity together with ideal mechanical properties.

Abstract Summary: Propagation rate coefficients, k p , for free‐radical polymerization of butyl acrylate (BA) previously reported by several groups are critically evaluated. All data were determined by the combination of pulsed‐laser polymerization (PLP) and subsequent polymer analysis by size exclusion (SEC) chromatography. The PLP‐SEC technique has been recommended as the method of choice for the determination of k p by the IUPAC Working Party on Modeling of Polymerization Kinetics and Processes . Application of the technique to acrylates has proven to be very difficult and, along with other experimental evidence, has led to the conclusion that acrylate chain‐growth kinetics are complicated by intramolecular transfer (backbiting) events to form a mid‐chain radical structure of lower reactivity. These mechanisms have a significant effect on acrylate polymerization rate even at low temperatures, and have limited the PLP‐SEC determination of k p of chain‐end radicals to low temperatures (<20 °C) using high pulse repetition rates. Nonetheless, the values for BA from six different laboratories, determined at ambient pressure in the temperature range of −65 to 20 °C mostly for bulk monomer with few data in solution, fulfill consistency criteria and show excellent agreement, and are therefore combined together into a benchmark data set. The data are fitted well by an Arrhenius relation resulting in a pre‐exponential factor of 2.21 × 10 7 L · mol −1 · s −1 and an activation energy of 17.9 kJ · mol −1 . It must be emphasized that these PLP‐determined k p values are for monomer addition to a chain‐end radical and that, even at low temperatures, it is necessary to consider the presence of two radical structures that have very different reactivity. Studies for other alkyl acrylates do not provide sufficient results to construct benchmark data sets, but indicate that the family behavior previously documented for alkyl methacrylates also holds true within the alkyl acrylate family of monomers. Arrhenius plot of propagation rate coefficients, k p , for BA as measured by PLP‐SEC. magnified image Arrhenius plot of propagation rate coefficients, k p , for BA as measured by PLP‐SEC.

The synthesis and radical polymerization of ionic liquids based on 1-vinyl imidiazole are described that led to a new family of poly(1-vinyl-3-alkyl-imidazolium) halides. Interestingly, the solubility of these polymers is easily tuned by a simple anion-exchange reaction. With this method new polyelectrolytes soluble in a variety of organic solvents such as acetone, 2-butanone, and tetrahydrofuran are easily prepared.

BACKGROUND: Glioblastoma multiforme (GBM) is the most frequent malignant brain tumor in adults, and its prognosis remains dismal despite intensive research and therapeutic advances. Diagnostic biomarkers would be clinically meaningful to allow for early detection of the tumor and for those cases in which surgery is contraindicated or biopsy results are inconclusive. Recent findings show that GBM cells release microvesicles that contain a select subset of cellular proteins and RNA. The aim of this hypothesis-generating study was to assess the diagnostic potential of miRNAs found in microvesicles isolated from the serum of GBM patients. METHODS: To control disease heterogeneity, we used patients with newly diagnosed GBM. In the discovery stage, PCR-based TaqMan Low Density Arrays followed by individual quantitative reverse transcriptase polymerase chain reaction were used to test the differences in the miRNA expression levels of serum microvesicles among 25 GBM patients and healthy controls paired by age and sex. The detected noncoding RNAs were then validated in another 50 GBM patients. RESULTS: We found that the expression levels of 1 small noncoding RNA (RNU6-1) and 2 microRNAs (miR-320 and miR-574-3p) were significantly associated with a GBM diagnosis. In addition, RNU6-1 was consistently an independent predictor of a GBM diagnosis. CONCLUSIONS: Altogether our results uncovered a small noncoding RNA signature in microvesicles isolated from GBM patient serum that could be used as a fast and reliable differential diagnostic biomarker.

The interest in confined crystallization has greatly increased with the development and progress of nanotechnology applications. Polymeric confined crystallization has been studied in droplets, ultrathin films, nanolayers, nanostructures from solutions, blends, copolymers, polymers infiltrated within AAO templates and nanocomposites. As confinement increases, the crystallization temperature first decreases, then splits into several fractions (i.e., fractionated crystallization) and finally occurs in one step at the maximum possible supercooling, near the glass transition temperature. Two factors are responsible for these effects: (a) a change in nucleation mechanism, from heterogeneous nucleation to surface nucleation (or in extreme cases, homogeneous nucleation), (b) the dependence of the crystallization temperature on the volume or the surface (or interphase) of the crystallizable micro or nanodomains. The melting point also decreases with confinement but to a lesser degree. A preferential orientation of polymeric crystals is generally induced by one or two dimensional confinement. Avrami indexes decrease with confinement until values of 1 (or even lower) are achieved in the limit of isolated domains, as the material approaches a first order crystallization kinetics. This type of kinetics reflects that nucleation is the rate determining step in the overall crystallization of ideally confined polymers.

Abstract Emulsion polymers are “products by process” whose main properties are determined during polymerization. In this scenario of margins reduction, increasing competition, and public sensitivity to environmental issues, the challenge is to achieve an efficient production of high‐quality materials in a consistent, safe, and environmentally friendly way. This highlight reviews the investigations carried out at The University of the Basque Country to develop a knowledge‐based strategy to achieve these goals. First, the research in fundamental mechanisms is discussed. This includes studies in radical entry and exit, oil‐soluble initiators, propagation‐rate constants of acrylic monomers, processes involved in the formation of branched and crosslinked polymers, microstructure modification by postreaction operations, the formation of particle morphology, and reactive surfactants. The advanced mathematical models developed in the group are also reviewed. In the second part, the advances in process development (optimization, online monitoring and control, monomer removal, production of high‐solids, low‐viscosity latices, and process intensification) are presented. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1025–1041, 2004

Chemical recycling of plastics offers a green method to deal with plastic waste. In this review, we highlight the recent advances made by applying organocatalysts to chemically degrade polymers as a promising tool to reach a circular plastic economy.

With increasing demands for safe, high capacity energy storage to support personal electronics, newer devices such as unmanned aerial vehicles, as well as the commercialization of electric vehicles, current energy storage technologies are facing increased challenges. Although alternative batteries have been intensively investigated, lithium (Li) batteries are still recognized as the preferred energy storage solution for the consumer electronics markets and next generation automobiles. However, the commercialized Li batteries still have disadvantages, such as low capacities, potential safety issues, and unfavorable cycling life. Therefore, the design and development of electromaterials toward high-energy-density, long-life-span Li batteries with improved safety is a focus for researchers in the field of energy materials. Herein, recent advances in the development of novel organic electrolytes are summarized toward solid-state Li batteries with higher energy density and improved safety. On the basis of new insights into ionic conduction and design principles of organic-based solid-state electrolytes, specific strategies toward developing these electrolytes for Li metal anodes, high-energy-density cathode materials (e.g., high voltage materials), as well as the optimization of cathode formulations are outlined. Finally, prospects for next generation solid-state electrolytes are also proposed.

Poly(3,4-ethylenedioxythiophene)s are the conducting polymers (CP) with the biggest prospects in the field of bioelectronics due to their combination of characteristics (conductivity, stability, transparency and biocompatibility). The gold standard material is the commercially available poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). However, in order to well connect the two fields of biology and electronics, PEDOT:PSS presents some limitations associated with its low (bio)functionality. In this review, we provide an insight into the synthesis and applications of innovative poly(ethylenedioxythiophene)-type materials for bioelectronics. First, we present a detailed analysis of the different synthetic routes to (bio)functional dioxythiophene monomer/polymer derivatives. Second, we focus on the preparation of PEDOT dispersions using different biopolymers and biomolecules as dopants and stabilizers. To finish, we review the applications of innovative PEDOT-type materials such as biocompatible conducting polymer layers, conducting hydrogels, biosensors, selective detachment of cells, scaffolds for tissue engineering, electrodes for electrophysiology, implantable electrodes, stimulation of neuronal cells or pan-bio electronics.

Linear and ribbon-like polycyclic aromatic hydrocarbons such as acenes and graphene nanoribbons are at the forefront of current investigations, as these graphene "cut outs" possess discrete energy gaps that can be tailored with the number of rings and their arrangements. Pyrene-fused pyrazaacenes are a type of nitrogenated ribbon-like polycyclic aromatic hydrocarbons with a very high stability. As a matter of fact, ribbon-like pyrene-fused pyrazaacenes with as many as 85 linearly fused aromatic rings have been synthesised with thermal stabilities over 500 °C in air. This review covers most of the synthetic and application aspects of pyrene-fused pyrazaacenes from 1937 to our days, illustrating that pyrene-fused pyrazaacenes are a widely tuneable and a highly stable platform for developing ribbon-like nitrogenated polycyclic aromatic hydrocarbons for a broad spectrum of applications.

An innovative temperature-resistant organocatalyst allows the depolymerisation of PET through a solvent-free process, opening routes to green recycling of common plastics.

The existence of a “memory” of the previous crystalline state, which survives melting and enhances recrystallization kinetics by a self-nucleation process, is well-known in polymer crystallization studies. Despite being extensively investigated, since the early days of polymer crystallization studies, a complete understanding of melt memory effects is still lacking. In particular, the exact constitution of self-nuclei is still under debate. In this Perspective, we provide a comprehensive and critical overview of melt memory effects in polymer crystallization. After the phenomenology of the process and some key concepts are introduced, the main experimental results of the past decades are summarized. Analogies and discrepancies of the melt memory characteristics of different polymeric systems are highlighted. Based on this background, the most significant interpretations and theories of melt memory effects are described, underlining that different interpretations may apply to various specific cases. Recent insights into self-nucleation, gained thanks to a multitechnique approach (combining calorimetry, rheology, and infrared and dielectric spectroscopies), are presented. The role of intra/interchain segmental contacts in the strength of melt memory effects, and the differences between homopolymers and copolymers behavior, are discussed. Finally, we identify areas where further research in the field is needed to shed light on the long-standing questions regarding the origin of melt memory effects in semicrystalline polymers.

Recently, self-healing polymers based on disulfide compounds have gained attention due to the versatile chemistry of disulfide bonds and easy implementation into polymeric materials. However, the underlying mechanisms of disulfide exchange which induce the self-healing effect in poly(disulfide)s remain unclear. In this work, we elucidate the process of disulfide exchange using a variety of spectroscopic techniques. Comparing a model exchange reaction of 4-aminophenyl disulfide and diphenyl disulfide with modified reactions in the presence of additional radical traps or radical sources confirmed that the exchange reaction between disulfide compounds occurred via a radical-mediated mechanism. Furthermore, when investigating the effect of catalysts on the model exchange reaction, it could be concluded that catalysts enhance the disulfide exchange reaction through the formation of S-based anions in addition to the radical-mediated mechanism.

Photopolymerization, or the use of light to trigger polymerization, is one of the most exciting technologies for advanced manufacturing of polymers. One of the key components in the photopolymerization processes is the photoactive compound that absorbs the light, generating the active species that promotes the polymerization and largely determines the final properties of the material. The field of photopolymerization has been dominated by photoradical generators to mediate radical reactions. In the last decade, to expand the number of polymers that can be prepared by photopolymerization, intensive research has been devoted to the synthesis and utilization of photoactive molecules that are able to generate a base or an acid upon irradiation. These organic compounds are known to promote not only the ring-opening polymerization of various heterocyclic monomers such as lactones, carbonates, or epoxides but also to trigger the step-growth synthesis of polyurethanes. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators, with the aim of encouraging the wider application of these photoactive compounds in the photopolymerization area and to expand the use of these polymers in advanced manufacturing processes.

Chemical recycling of plastic waste represents a greener alternative to landfill and incineration, and potentially offers a solution to the environmental consequences of increased plastic waste. Most plastics that are widely used today are designed for durability, hence currently available depolymerisation methods typically require harsh conditions and when applied to blended and mixed plastic feeds generate a mixture of products. Herein, we demonstrate that the energetic differences for the glycolysis of BPA-PC and PET in the presence of a protic ionic salt TBD:MSA catalyst enables the selective and sequential depolymerisation of these two commonly employed polymers. Employing the same procedure, functionalised cyclic carbonates can be obtained from both mixed plastic wastes and industrial polymer blend. This methodology demonstrates that the concept of catalytic depolymerisation offers great potential for selective polymer recycling and also presents plastic waste as a "greener" alternative feedstock for the synthesis of high added value molecules.