: The encapsulation of colloidal lead halide perov-skite nanocrystals within silica (SiO 2 ) is one of the strategies to protect them from polar solvents and other external factors. Here, we demonstrate the overcoating of CsPbBr 3 perovskite nanocrystals with silica by exploiting the anhydride-induced transformation of Cs 4 PbBr 6 nanocrystals. CsPbBr 3 @SiO 2 core − shell nanocrystals are obtained after (i) a reaction between colloidal Cs 4 PbBr 6 nanocrystals and maleic anhydride in toluene that yields CsPbBr 3 nanocrystals and maleamic acid and (ii) a silica-shell growth around CsPbBr 3 nanocrystals via hydrolysis of added alkoxysilanes. The reaction between Cs 4 PbBr 6 nanocrystals and maleic anhydride is necessary to promote shell formation from alkoxysilanes, as demonstrated in control experiments. The best samples of as-prepared CsPbBr 3 @SiO 2 nanocrystals consist of ∼ 10 nm single-crystal CsPbBr 3 cores surrounded by ∼ 5 − 7 nm amorphous silica shell. Despite their core − shell structure, such nanostructures are poor emitters and degrade within minutes of exposure to ethanol. The photoluminescence intensity of the core − shell nanocrystals is improved by the treatment with a solution of PbBr 2 and ligands, and their stability in ethanol is extended to several days after applying an additional silica growth step. Overall, the investigated approach outlines a strategy for making colloidal core − shell nanocrystals utilizing the transformative chemistry of metal halides and reveals interesting insights regarding the conditions required for CsPbBr 3 @SiO 2 nanocrystal formation.

This paper reports the optimization of a two-step atmospheric pressure plasma process to modify the surface properties of a polyurethane (PU) foam and, specifically, to prepare a superhydrophobic/superoleophilic absorbent for the removal of oils and nonpolar organic solvents from water. In particular, in the first step, an oxygen-containing dielectric barrier discharge (DBD) is used to induce the etching/nanotexturing of the foam surfaces; in the second step, an ethylene-containing DBD enables uniform overcoating with a low-surface-energy hydrocarbon polymer film. The combination of surface nanostructuring and low surface energy ultimately leads to simultaneous superhydrophobic and superoleophilic wetting properties. X-ray photoelectron spectroscopy, scanning electron microscopy and water contact angle measurements are used for the characterization of the samples. The plasma-treated PU foam selectively absorbs various kinds of hydrocarbon-based liquids (i.e., hydrocarbon solvents, mineral oils, motor oil, diesel and gasoline) up to 23 times its own weight, while it completely repels water. These absorption performances are maintained even after 50 absorption/desorption cycles and after immersion in hot water as well as acidic, basic and salt aqueous solutions. The plasma-treated foam can remove mineral oil while floating on the surface of mineral oil/water mixtures with a separation efficiency greater than 99%, which remains unaltered after 20 separation cycles.

The presence of micro- and nanoplastics in the marine environment is raising strong concerns since they can possibly have a negative impact on human health. In particular, the lack of appropriate methodologies to collect the nanoplastics from water systems imposes the use of engineered model nanoparticles to explore their interactions with biological systems, with results not easily correlated with the real case conditions. In this work, we propose a reliable top-down approach based on laser ablation of polymers to form polyethylene terephthalate (PET) nanoplastics, which mimic real environmental nanopollutants, unlike synthetic samples obtained by colloidal chemistry. PET nanoparticles were carefully characterized in terms of chemical/physical properties and stability in different media. The nanoplastics have a ca. 100 nm average dimension, with significant size and shape heterogeneity, and they present weak acid groups on their surface, similarly to photodegraded PET plastics. Despite no toxic effects emerging by in vitro studies on human Caco-2 intestinal epithelial cells, the formed nanoplastics were largely internalized in endolysosomes, showing intracellular biopersistence and long-term stability in a simulated lysosomal environment. Interestingly, when tested on a model of intestinal epithelium, nano-PET showed high propensity to cross the gut barrier, with unpredictable long-term effects on health and potential transport of dispersed chemicals mediated by the nanopollutants.

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[This corrects the article DOI: 10.1039/D0SC00738B.].

All-PLA blends have been fabricated by an easily scalable and green melt-blending of linear-PLLA and 3-armed star-shaped PDLLA at different proportions (100:0, 95:5, 90:10, 80:20, and 50:50, w:w). The fabrication process, carried out in a hot-press, consisted of three steps: an initial heating of the thoroughly blended polymer mixtures at 170 degrees C for 5 min, a second heating at 170 degrees C for 5 min with a pressure of 200 Pa, and a final cooling at room temperature during 20 min keeping the same pressure. This methodology resulted in very homogenous amorphous samples, as revealed by XRD and DSC. The incorporation of star-PDLLA toughened the polylactide matrix by a clear ductilization, opening opportunities for the expanded use of the developed blends in different applications, due to their increased processability. DSC analysis revealed indeed that by increasing star-PDLLA content it is possible to gradually reduce the T-g, as well as the capability of crystallization of the linear-PLLA component. Such properties determine a plasticizing effect on the final blends. The increased content of the star component turned the films from transparent to translucent and decreases the thermal decomposition temperatures, which remain in any case very well above room temperature. The water vapor transmission rates varied with the star-PDLLA content between values characteristic for isolating to breathable films, thus allowing the use of these blends in different applications such as food packaging and biomedical devices. Finally, no important changes of water contact angle and water uptake were observed between the different blends. Despite the negligible effect of seawater on the biodegradation of commercial PLA, star-PDLLA-containing blends showed high biodegradation rates at short-times in marine environments, reinforcing the environmentally friendly character of polylactide.

The preparation of strongly emissive CsPbBr3 perovskite nanocrystals with a robust surface passivation is a challenge in the field of lead halide perovskite nanomaterials. We report an approach to prepare polymer-capped CsPbBr3 perovskite nanocrystals by reacting oleylammonium/oleate-capped Cs4PbBr6 nanocrystals with poly(maleic anhydride-alt-1-octadecene) (PMAO). PMAO contains succinic anhydride units that are reactive towards the oleylamine species present on Cs4PbBr6 nanocrystals’ surface and produces polysuccinamic acid, which, in turn, triggers the Cs4PbBr6 to CsPbBr3 conversion. The transformation occurs through the formation of Cs4PbBr6-CsPbBr3 heterostructures as intermediates, which were captured because of the mild reactivity of PMAO and were investigated by high-resolution electron microscopy. The Cs4PbBr6-CsPbBr3 heterostructures demonstrate a dual emission at cryogenic temperature with an indication of the energy transfer from Cs4PbBr6 to CsPbBr3. The fully-transformed CsPbBr3 NCs have high photoluminescence quantum yield and enhanced colloidal stability, which we attribute to the adhesion of polysuccinamic acid to the NC surface through its multiple functional groups in place of oleate and alkylammonium ligands. The PMAO-induced transformation of Cs4PbBr6 NCs opens up a strategy for the chemical modification of metal halide NCs initially passivated with nucleophilic amines.

Beeswax is a natural hydrophobic phase change material. Its proper use in superhydrophobic coatings means increased use of eco-friendly materials in superhydrophobicity and also functionality. These low-cost coatings can store latent heat and can be eventually implemented in solar heating and cooling of buildings for significant energy savings. More can be found in article number 1801782 by Sara Naderizadeh, Ilker S. Bayer, and co-workers.

Poly(furfuryl alcohol) (PFA) is a bioresin synthesized from furfuryl alcohol (FA) that is derived from renewable saccharide-rich biomass. In this study, we compounded this bioresin with polycaprolactone (PCL) for the first time, introducing new functional polymer blends. Although PCL is biodegradable, its production relies on petroleum precursors such as cyclohexanone oils. With the method proposed herein, this dependence on petroleum-derived precursors/monomers is reduced by using PFA without significantly modifying some important properties of the PCL. Polymer blend films were produced by simple solvent casting. The blends were characterized in terms of surface topography by atomic force microscopy (AFM), chemical interactions between PCL and PFA by attenuated total reflection-Fourier transform infrared (ATR-FTIR), crystallinity by XRD, thermal properties by differential scanning calorimetry (DSC), and mechanical properties by tensile tests and biocompatibility by direct and indirect toxicity tests. PFA was found to improve the gas barrier properties of PCL without compromising its mechanical properties, and it demonstrated sustained antioxidant effect with excellent biocompatibility. Our results indicate that these new blends can be potentially used in diverse applications ranging from food packing to biomedical devices.

Dispersions of oleate-capped ZnO nanoparticles (NPs) in binary n-octane/1,7-octadiene solvent mixtures are injected, in aerosol form, in a dielectric barrier discharge to deposit hydrocarbon polymer/ZnO nanoparticles nanocomposite (NC) thin films at atmospheric pressure and room temperature. The chemical composition of the coatings, and in turn their morphology and wettability, can be tuned by simply changing the composition of the starting dispersion. Specifically, the increase of the NPs concentration in the dispersion (0.5-5 wt%) results in a continuous increase of both the ZnO content and deposition rate of the coatings. Moreover, when the concentration of 1,7-octadiene in the solvent mixture is very low (0.5-2 vol%), the incorporation of NPs is further promoted, while at concentrations > 2 vol% the growth of the organic component starts to be favored. Overall, results reveal a considerable increase of the root-mean-square (RMS) roughness of the coatings with the ZnO loading. In addition, once the threshold ZnO loading and RMS roughness of 60 wt% and 350 nm are reached, respectively, the coatings are superhydrophobic and exhibit very low water contact angle hysteresis, due to the coexistence of the low surface energy conferred by the hydrocarbon polymer and the hierarchical multiscale surface texture induced by NPs incorporation.

Polyvinylpyrrolidone (PVP) has probably been one of the most utilized pharmaceutical polymers with applications ranging from a blood plasma substitute to nanoparticle drug delivery, since its synthesis in 1939. It is a highly biocompatible, non-toxic and transparent film forming polymer. Although high solubility of PVP in aqueous environment is advantageous, it still poses several problems for some applications in which sustained targeting and release are needed or hydrophobic drug inclusion and delivery systems are to be designed. In this study, we demonstrate that a common dietary phenolic antioxidant, p-coumaric acid (PCA), can be combined with PVP covering a wide range of molar ratios by solution blending in ethanol, forming new transparent biomaterial films with antiseptic and antioxidant properties. PCA not only acts as an effective natural plasticizer but also establishes H-bonds with PVP increasing its resistance to water dissolution. PCA could be released in a sustained manner up to a period of 3 days depending on the PVP/ PCA molar ratio. Sustained drug delivery potential of the films was studied using methylene blue and carminic acid as model drugs, indicating that the release can be controlled. Antioxidant and remodeling properties of the films were evaluated in vitro by free radical cation scavenging assay and in vivo on a murine model, respectively. Furthermore, the material resorption of films was slower as PCA concentration increased, as observed from the in vivo full-thickness excision model. Finally, the antibacterial activity of the films against common pathogens such as Escherichia coli and Staphylococcus aureus and the effective reduction of inflammatory agents such as matrix metallopeptidases were demonstrated. All these properties suggest that these new transparent PVP/ PCA films can find a plethora of applications in pharmaceutical sciences including skin and wound care.

Beeswax particles are homogenously emulsified in commercial aqueous polymer dispersion, without additional dispersing agents and surfactants. Emulsions display very good stability with wax droplet size distribution around 350 nm. The wax to polymer ratio in the emulsions can be tuned without compromising emulsion stability. The emulsions are spray coated in order to create either hydrophobic or superhydrophobic coatings. For superhydrophobicity, silica nanoparticles are dispersed in the emulsions at different concentrations. Beeswax‐rich coatings such as the ones with 1:1 beeswax:polymer ratio or more, including the superhydrophobic ones, demonstrate promising latent heat storage characteristics, suitable for thermal management applications. Electron microscopy studies show that as a result of emulsification, the polymer encapsulates the wax droplets/particles as a nanothin shell, preventing a major problem related to low melting point phase change materials referred to as leaching. Hence, the coatings can be heated well above the melting point of beeswax (≈62 °C) and can still demonstrate effective heat storage during the cooling stage. This water‐based coating process using ecofriendly material constituents can easily be scaled up and used in responsive coating applications, ranging from electronics to interior or exterior structural buildings requiring efficient energy management and thermal energy savings.

Bioplastics were prepared from the fatty fraction (i.e., unsaturated and polyhydroxylated fatty acids) of tomato pomace agro-wastes. Aliphatic polyesters were synthesized at different temperatures (125, 150, and 175 degrees C), reaction times (0.25, 0.5, 0.75,1, 3, 5, and 7 h), and amounts of tin (II) 2-ethylhexanoate (0, 0.02, 0.05, and 0.10 mmol) used as a catalyst. The rate constants and activation energies were calculated from infrared spectra. The right combination of reaction temperature and amount of catalyst improved the reaction kinetics (apparent k from similar to 1 to similar to 8.5 h(-1)), whereas the activation energy was reduced from similar to 39 without catalyst to similar to 28 kJ/mot when tin (II) 2-ethylhexanoate was present. Glass transitions between ca. -25 and similar to 0 degrees C were measured by differential scanning calorimetry, strictly depending on the degree of polymerization. The amorphous character of the samples was confirmed by X-ray diffraction. Young's modulus and hardness were calculated from indentation tests and were typical of soft materials, although increased as the polycondensation reaction progressed. High water-contact angles (maximum value similar to 109 degrees) and low water uptakes (minimum value similar to 2.1%) were determined. Physical properties were compared with those of common man-made plastics and polymers, finding that these tomato pomace bioplastics could be their realistic alternatives. (C) 2018 Elsevier Ltd. All rights reserved.

Superhydrophobic materials hold an enormous potential in sectors as important as aerospace, food industries, or biomedicine. Despite this great promise, the lack of environmentally friendly production methods and limited robustness remain the two most pertinent barriers to the scalability, large-area production, and widespread use of superhydrophobic materials. In this work, highly robust superhydrophobic silicone monoliths are produced through a scalable and environmentally friendly emulsion technique. It is first found that stable and surfactantless water-in-polydimethylsiloxane (PDMS) emulsions can be formed through mechanical mixing. Increasing the internal phase fraction of the precursor emulsion is found to increase porosity and microtexture of the final monoliths, rendering them superhydrophobic. Silica nanoparticles can also be dispersed in the aqueous internal phase to create micro/nanotextured monoliths, giving further improvements in superhydrophobicity. Due to the elastomeric nature of PDMS, superhydrophobicity can be maintained even while the material is mechanically strained or compressed. In addition, because of their self-similarity, the monoliths show outstanding robustness to knife-scratch, tape-peel, and finger-wipe tests, as well as rigorous sandpaper abrasion. Superhydrophobicity was also unchanged when exposed to adverse environmental conditions including corrosive solutions, UV light, extreme temperatures, and high-energy droplet impact. Finally, important properties for eventual adoption in real-world applications including self-cleaning, stain-repellence, and blood-repellence are demonstrated.

Cellulose acetate oleate ester has been synthesized from oleic acid and cellulose acetate by using a mixed anhydride system based on a mixture of trifluoroacetic acid and trifluoroacetic acid anhydride with chloroform as a co-solvent. In absence of oleic acid, cellulose acetate was deacetylated in this mixed anhydride system. However, when oleic acid was added, hydrolysis was prevented and oleate groups bound to the cellulose acetate chain were detected as confirmed by Nuclear Magnetic Resonance spectroscopy. Compared to cellulose acetate, cellulose acetate oleate ester showed a mechanical behavior closer to ductile materials and a lower glass transition temperature, indicating that oleate groups can act as an internal plasticizer of the polymer chains. The contact angle values increased from 61 degrees for cellulose acetate to 106 degrees for cellulose acetate oleate, which presented a low surface energy value (16 mJ/m(2)) with no contribution of the polar component. Furthermore, the esterified cellulose acetate oleate material showed a decrease in the water vapor transmission rates by similar to 76% compared to those of pure cellulose acetate films. The oxygen permeability was also decreased by similar to 90% after grafting the oleate group onto the cellulose acetate repetitive units because of the creation of a densely packed matrix, confirmed by SEM analysis. This behaviour was attributed to the oleate chain length, which creates a chemical interaction between water and oxygen molecules with free hydroxyl and oleate groups of cellulose acetate oleate.

Lanthanide-activated SrF2 nanoparticles with a multishell architecture were investigated as optical thermometers in the biological windows. A ratiometric approach based on the relative changes in the intensities of different lanthanide (Nd3+ and Yb3+) NIR emissions was applied to investigate the thermometric properties of the nanoparticles. It was found that an appropriate doping with Er3+ ions can increase the thermometric properties of the Nd3+-Yb3+ coupled systems. In addition, a core containing Yb3+ and Tm3+ can generate light in the visible and UV regions upon near-infrared (NIR) laser excitation at 980 nm. The multishell structure combined with the rational choice of dopants proves to be particularly important to control and enhance the performance of nanoparticles as NIR nanothermometers.

A photoresponsive microstructured composite is fabricated through the impregnation of cellulosic filter paper (FP) with a spiropyran-modified acrylic polymer. The polymer enwraps uniformly each individual cellulose fiber, increases the thermal stability of cellulose, and ensures the preservation of the composite functionalities even upon removal of the surface layers through mechanical scratching. The photochromic spiropyran moieties of the polymer, even while embedded in the cellulosic sheet, can reversibly interconvert between the colorless spiropyran and the pink merocyanine isomeric states upon irradiation with UV and visible light, respectively. Moreover, the photochromic polymer presents a faster photochromic response and a higher resistance to photodegradation, with an outstanding reusability for more than 100 switching cycles when it is incorporated in the cellulose network. Most importantly, the acidochromism of the modified FP, attributed to the spiropyran molecules after UV activation, allows the real-time optical and visual detection of acidity changes and spoilage in food products, such as wine and milk. Spoilage due to bacterial degradation and oxidation processes generates acidic vapors that induce the protonation of the merocyanine. This results in a visually detectable chromic transition from pink to white of the treated cellulose fibers, corresponding to a blue shift in the absorption spectrum. The developed photoresponsive cellulose composite can serve as cost-effective robust optical component in integrated functional platforms and consumer-friendly indicators for smart food packaging, as well as portable on demand acidoresponsive interfaces for gas monitoring in industrial and environmental applications.

A major user of nanoparticles (NPs) is the pigment and ink industry, where NPs are incorporated into numerous products (e.g. paints, food, plastics, printers, personal care products, and construction materials). Assessment of NP toxicity requires potential impacts on human health and the environment to be evaluated. In this study, we examined the toxicity of a range of NPs, of varied physico-chemical properties, used in the pigment and ink industries including silver (Ag), iron oxide (Fe2O3), titanium dioxide (TiO2), aluminium oxide (Al2O3), zinc oxide (ZnO), cobalt aluminium oxide (CoAl2O4) and cadmium selenide/zinc sulphide (CdSe/ZnS) quantum dots (QDs). Acute toxicity exerted by this NP panel to mammalian cells in vitro (macrophages, hepatocytes and alveolar epithelial cells) and aquatic environmental organisms (Raphidocelis subcapitata Daphnia magna, Lumbriculus variegatus) was investigated. For mammalian cells, cytotoxicity was assessed 24 h post exposure, at concentrations ranging from 1 to 125 μg/ml using the LDH and WST-1 assays. The aquatic toxicity of the NP panel was assessed according to OECD protocols (201, 202, 315), up to 96 h post exposure. Rats were exposed to selected NPs via intratracheal instillation (62 μg) and the pulmonary inflammatory response quantified 24 h post exposure. This cross-species comparison revealed that Ag, QDs and ZnO NPs were consistently more toxic than the other NPs tested. By looking across mammalian and aquatic ecotoxicological models we obtained a better understanding of the sensitivity of each model, and thus which models should be prioritised for selection in the future when assessing the mammalian and ecotoxicity of NPs, and in particular when screening the toxicity of a panel of NPs. We recommend that macrophage and daphnia models are prioritised when assessing the mammalian toxicity and ecotoxicity of NPs, respectively, due to their increased sensitivity, compared to the other models tested. Of interest is that the in vitro and invertebrate models used were able to predict the toxic potency of the NPs in rodents, and thus our approach has the potential to enhance the implementation of the 3Rs principles in nanotoxicology and reduce reliance on rodent testing when assessing NP safety. By identifying hazardous NPs the data obtained from this study can feed into the selection of (low toxicity) NPs to use in products and will also contribute to the safe design of future generations of NPs used by the pigment and ink industries.