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In this work, we describe the preparation and characterization of supramolecular ionic liquid gels based on binary mixtures of biopolymers, comprising chitosan, chitin, cellulose and lignin. The gels were obtained in ionic liquids differing in the cation or the anion, with no need for a cross-linking agent or acid treatment. The materials obtained were characterized for the minimum gelation concentration, porosity, swelling and rheological properties, finding a prominent influence of the nature of the ionic liquid anion. Then, we investigated the ability of the gels to scavenge free radicals, finding that the gels exhibit a higher antioxidant ability than their individual components. Moreover, our gels showed a bactericidal activity toward Gram-positive and Gram-negative bacterial strains like Streptomyces coelicolor and Escherichia coli, respectively. The kinetics of bacterial cell viability showed that the gel based on a chitosan : chitin mixture in the IL [bmim][Cl] was the fastest acting against E. coli, with a practically total killing of bacterial cells within 30 min. Once again, a major influence of the ionic liquid anion was detected. Finally, we found an inverse relationship between the antioxidant and antimicrobial activities of our gels.

In the last two decades, the continuous ever growing demand for energy has determined a significant development in the production of photovoltaic (PV) modules. Anyway, a critical and very important issue in the module design process is the adoption of suitable encapsulant materials and technologies for cell embedding. Therefore, adopted encapsulants have a significant impact on modules efficiency, stability and reliability, and to ensure the unchanged performance of PV modules in time, the encapsulant materials must be selected properly. The selection of encapsulant materials must maintain a good balance between the encapsulant performance in time and costs, related to materials production and technologies for cells embedding. However, the encapsulants must ensure excellent isolation of active photovoltaic elements by the environment, preserving accurately the PV cells against humidity, oxygen and accidental causes that may compromise the PV modules function. This review provides an overview of different encapsulant materials, their main advantages and disadvantages in adoption for PV production, and also in relation to used encapsulant technologies for cell embedding, additives and the interaction of these materials with other PV components.

In the last two decades, the naturally occurring polysaccharides have gained great attention because of their potential applications in different sectors, for example, from food to biomedical sectors. Chitosan is a cationic polysaccharide with good transparency, and currently, it has been considered also as suitable material for the formulation film and coating in cultural heritage protection. In this work, the chitosan films (Ch), with and without natural antioxidant such as citric acid (CA), are formulated considering two different processing techniques: (i) conventional solvent casting and (ii) compression molding, that is an unconventional method for this polysaccharide, giving the possibility to formulate films with extended surface and constant thickness. The effects of processing conditions and antioxidant presence on the properties and performance are evaluated by thermo-gravimetric analysis, FTIR and UV-visible spectroscopy, water contact angle measurements and tensile test. Besides, the durability of all investigated Ch and Ch/CA has been evaluated subjecting thin film to UVB exposure and monitoring their structural changes by FTIR analysis in time. All obtained results suggest that the chitosan films can be processed successfully by both solvent casting and compression molding techniques. Further, the CA presence in Ch films has a beneficial effect on the thermal resistance and durability and no negative effect on the transparency and optical properties.

To obtain road bitumen with improved temperature and fatigue resistance, polymers and/or rubbers could be added to it. A particularly suitable polymer for bitumen modification is styrene-butadiene-styrene (SBS) copolymer but limited information is available about the ageing behaviour of modified binders. In this work, two neat bitumens, with different penetration grades, and two SBS-modified bitumens, containing different SBS amounts, were selected, and their short-term and UVB ageing behaviour were investigated considering dynamic shear rheometry and Attenuated Total Reflectance-Fourier Transformation InfraRed spectroscopy (ATR-FTIR). Short-time ageing behaviour was investigated performing the rolling thin film oven test (RTFOT), while artificial UV ageing was examined/investigated using UVB lamps. The structural changes in bitumen were monitored at different UV exposure times. All the results suggest that the bitumen having higher penetration grade is more stable than the one with a lower penetration grade in the RTFOT ageing condition, and SBS addition exerts a beneficial effect on thermal stability during processing. Further, SBS addition also has a beneficial effect on the UV ageing resistance of bitumen, reducing its oxidation tendency.

Adding nanoparticles to a host polymer can lead to performance improvements that can be twice as beneficial to the environment: first, sustainable nanocomposites based on bioplastics or recycled plastics could replace ubiquitous petroleum-based polymers; second, substantial plastic saving could be achieved by profiting from the superior specific properties of the nanocomposites. Nevertheless, the inherent environmental burden of nanoparticles can compromise the expected benefits. Here we address the controversial issue of the environmental sustainability of “green” polymer nanocomposites based on bioplastics and recycled plastics. A critical review of life-cycle assessment studies regarding nanocomposites and their individual constituents is presented. Nanoparticles have a remarkable environmental impact despite their typically low content. Except for organo-clays and graphene, the production of common nanofillers (nanocellulose, titanium dioxide, silver and, above all, carbon nanotubes) emits relevant amounts of greenhouse gases and requires high energy, nullifying the advantages of using green polymer matrices. Reaching high performance becomes hence crucial to make polymer nanocomposites truly sustainable through material saving. For this purpose, increasing the content of nanoparticles or functionalizing them to enhance their dispersion in the host polymer can unexpectedly entail environmental benefits.

In an attempt to perform polycarbonate chemical recycling in a more sustainable way, we took into consideration the combined use of ultrasound irradiation and task specific ionic liquids. Towards this aim, the methanolysis of polycarbonate, into dimethylcarbonate and bisphenol A, was carried out in the presence of cholinium-based ionic liquids featuring anions derived from amino acids and other eco-friendly species. The target process was optimized in terms of both energy and material amounts as well as in terms of the nature of the catalysts used. The proposed protocol allowed high conversion and yields of bisphenol A to be obtained, under milder conditions compared to the ones so far reported in the literature, perfectly fulfilling green chemistry principles. The best performing catalyst can be reused without significant loss in performance and the methodology can be successfully applied to post-consumer polycarbonate samples. This journal is

Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems has been emerging in politics, industry, and academia. The issue is exacerbated by the increased use of FRPs in the automotive industry and by the expected decommissioning of airplanes and wind turbines amounting to thousands of metric tons of composite materials. Currently, the recycling of FRPs downcycles the entire composite to some form of reinforcement material (typically for cements) or degrades the polymer matrix to recover the fibers. Following the principles of sustainability, the reuse and recycling of the whole composite—fiber and polymer—should be promoted. In this review paper, we report on recent research works that achieve the recycling of both the fiber and matrix phase of FRP composites, with the polymer being either directly recovered or converted to value-added monomers and oligomers.

International audience; In this work, polymer blends based on ethylene vinyl acetate (EVA) and polyolefin (PO) at different weight ratios, also in the presence of a crosslinking agent (CA) and stabilizers (STAB), were investigated as potential encapsulants for PV modules. The EVA/PO blends were processed by melt mixing and then subjected to compression moulding following industrial lamination processing conditions. The EVA/PO films were characterized by mechanical tensile tests and thermogravimetric analysis, and the obtained results highlight the beneficial effect of PO at low amounts on the mechanical behaviour and thermal resistance at high temperatures (>300 °C). All EVA/PO films were subjected to UVB exposure, and the photoaging extent was monitored by FTIR and UV-visible spectroscopies. Therefore, EVA-rich blends can be considered as good candidates for PV module encapsulants, given a compromise in the behaviour before and after photoaging.

Hypothesis: Performances of materials are frequently affected by the action of radicals that can induce their degradation. To overcome the above issue, natural antioxidants (AOs) can be added during manufacturing. Considering the high instability of AOs, they have been adsorbed on carbon nanomaterials surface. However, the inclusion of functionalized carbon nanomaterials into gel matrix could enhance the antioxidant efficiency and represent an easy way to disperse and handle the active species.Experiments: Carboxypropyl functionalized carbon nanotubes (f-CNT), pure or with physically adsorbed alpha-tocopherol (f-CNT-VE) and quercetin (f-CNT-Q), were incorporated in some ionic liquid gels (ILGs) formed by 1,3-didodecylimidazolium-based salts. Temperature of gel-sol transition, morphology, response to external stimuli and rheology of hybrid ILGs (HILGs) were investigated before their use as radical scavengers. To this purpose a free radical test was performed on gels.Findings: The properties of HILGs significantly differ from the ones of pure ILGs, as CNTs appreciably improved gel rheological response. Besides, the gel network is able to enhance radical scavenging activity of both natural AOs and f-CNTs, achieving a complete radical reduction in less than 1 h. Furthermore, the activity is also preserved in thin films obtained from HILGs, opening the way to the application of these systems as material coatings. (C) 2019 Elsevier Inc. All rights reserved.

Different human activities have caused and currently cause catastrophic environmental phenomena, and unfortunately, a significant negative contribution to these catastrophic phenomena can be attributed to uncontrolled plastic production, use and release everywhere. On the other hand, the plastics offer numerous comforts and advantages, and for this reason, the modern life is unthinkable without plastic. Currently, numerous scientific papers and large audience advertisings, related to the production and use of polymers made by natural sources, i.e. bio-based polymers, as a valid alternative to the petroleum-based counterparts, have been published. Therefore, for production of daily disposables and usages, the choice of petroleum-based polymers, coming from fossil-based resources, or bio-based polymers, coming from renewable resources, can be correctly understood and evaluated taking into account different issues concerning resources supplying, production technology and costs, application properties and performance, and finally, waste management. Current paper is focused on a reflection point related to waste management through burning/incineration (i.e. oxidation) of disposable beverage cups (volume 200 ml). The simple calculations of oxidation process of petrol-based or bio-based materials, which is the theoretical basis of waste management through burning/incineration, highlights that none of cup materials, can be considered better than the others to produce daily disposables and usages.

Current concerns for sustainability and the environment make low-impact materials desirable for environmental remediation and, in particular wastewater treatment. We obtained supramolecular gels of l-amino acids in the deep eutectic solvent formed by choline chloride and phenylacetic acid. After gel characterization, and investigating gel-sol transition temperatures, gelation kinetics, rheological properties, and morphology, the gels were applied as sorbents to remove cationic dyes from aqueous solutions. The effects of the pH, dye nature, volume, and concentration of wastewater were analyzed, and the best result was obtained with a l-phenylalanine-based eutectogel. It can be reused for at least 9 times without losing efficiency, also with dye mixtures. Interestingly, this gel can be loaded onto columns to decolorize flowing solutions, achieving 85 % of removal efficiency in only 10 minutes and allowing its reuse for at least 4 cycles. In terms of adsorption capacity, this eutectogel is competitive with efficient gel-based dye sorbent systems, with a value 1930 mg/g reached at a high concentration of rhodamine B 479 mg/L.

Eco-friendly in-situ stabilised biopolymer nanocomposites based on polyamide 11 (PA11) and polylactic acid (PLA) were prepared by melt mixing in the presence of a modified organo-montmorillonite clay containing a chemically-bound hindered amine UV-stabilising function, [(UV)OM-MMt]. Characterisation of the newly synthesised organo-modifier containing the reactive hindered amine (HAS) UV-stabilising function [(UV)OM] has confirmed a successful synthesis. The (UV)OM was then introduced into NaMMt through ion exchange reaction to prepare the UV stabiliser-bound organo-modified-MMt, [(UV)OM-MMt]. The in-situ stabilised PA11- and PLA- nanocomposites (PA11-(UV)OM-MMt and PLA-(UV)OM-MMt) were characterised and their photoxidative stabilities (under accelerated weathering conditions) were compared with their nanocomposite analogues containing either the organo-modified MMt (OM-MMt) alone (i.e. without UV-stabiliser) or the OM-MMT containing conventionally added commercial hindered amine HAS-UV-stabiliser (Cyasorb® UV-3853). It was found that both of the newly prepared in-situ stabilised PA11- and PLA- nanocomposites gave good clay dispersion and have demonstrated a much higher, especially in PLA-nanocomposites, photo-oxidative stability compared to the corresponding nanocomposites but in the absence, or the presence, of the conventionally added HAS-UV-stabiliser.

Water contamination is one of the main problems of modern society, and scientific research is continuously involved in identifying solutions able to preserve this valuable source. In this context, we characterized novel ionogels formed by organic salts with different anions. In particular, they show self-strengthening behavior, a quite unusual property for supramolecular gels, and they also exhibit a good load-bearing capacity. These ionogels are able to remove cationic dyes from wastewater. Thanks to their properties, they can be used in different apparatuses like dialysis membranes and as loading in adsorption columns. In the latter case over 95% removal is achieved in less than 10 min. Interestingly, soft materials can be reused for at least 20 cycles, partially regenerated, and reused for further 15 cycles. Comparison with data previously reported in the literature shows that this is a prerogative of this system and this represents not only an improvement but also a warranty of low raw material production after wastewater treatment.

Carbon Nanotubes (CNT) and Graphene Nanoplatelets (GNP) were incorporated in Polypropylene (PP) as single filler (CNT=1, 2 and 4 %wt. and GNP=2, 4, and 6 %wt.) and in hybrid form (CNT:GNP weight ratio 2:2, 2:4 and 4:2) using a prototype miniature Twin Screw Extruder (TSE) coupled with a double slit rheological die, in order to assess in-line the extent of nanofiller dispersion and to deliver PP-based nanocomposites with enhanced thermo-oxidative stability. The morphological, electrical and mechanical properties, as well as the resistance to thermal and photo degradation of the composites containing single nanofillers (PP/CNT and PP/GNP) were compared with those of hybrid PP based nanocomposites (PP/CNT:GNP). The results highlight that the presence of the two carbonaceous nanofillers exerts a positive synergic effect on the nanocomposite properties. Moreover, the radical scavenging role of the carbonaceous nanofillers was investigated under thermomechanical, thermo- and photo degradation conditions, the results confirming that aspect ratio, loading and dispersion level of the filler play a determinant role in the nanocomposite durability., This research was funded in part by National Funds through FCT – Portuguese Foundation for Science and Technology, Reference UID/CTM/50025/2019. LH acknowledges funding from the FCT Investigator Programme through grant IF/00606/2014.

In this work, different naturally occurring phenolic compounds, such as Thymol (Th), Vanillic acid (VA) and Ferulic Acid (FA), have been considered as UV stabilizers against the photo-oxidative degradation of polylactic acid (PLA). Particularly, in order to explore the effectiveness of the naturally occurring stabilizers, thin PLA-based films, containing different amount of the stabilizers, have been formulated and subjected to accelerate UVB exposure. The preliminary characterizations suggest that the all considered stabilizers exert a plasticizing action and the overall crystallinity of the samples is slightly reduced. If the considered stabilizers are added at low concentration, they exert a protection action, but if their content overcome a specific threshold, are able to exert a pronounced pro-degradation action. Overall, in this work, the concentration-dependent anti-/pro- oxidant activity of used naturally occurring phenolic compounds has been accurately investigated and reported.

Poly(butylene succinate) (PBS) was grafted on the surface of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) modified multi-walled carbon nanotubes (MWCNTs) via a nitroxide radical coupling reaction. TEMPO functionalized MWCNTs (MWCNTs-g-TEMPO) were synthesized using the Cu(I)-catalyzed azide/alkyne click chemistry approach and the covalent bond of the nitroxide moieties onto the MWCNTs was confirmed via electron paramagnetic resonance (EPR) spectroscopy. The PBS grafting on the sidewalls of MWCNTs was carried out in solution via peroxide-induced formation of macroradicals and it was confirmed by EPR and attenuated total reflectance Fourier transform infrared analysis. Preliminary rheological and calorimetric analyses revealed that the grafting improves both the quality of stress transfer across the polymer − nanotube interface and the degree of dispersion of the filler, which also exhibited a moderate nucleating action on the PBS. Overall, our results demonstrate that nitroxide radical coupling is an efficient and feasible ‘grafting to’ method to covalently bond polymer chains on MWCNTs with possible advantages in the final properties of the polymer nanocomposites. © 2015 Society of Chemical Industry

Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get information about the organisation of the gelator in the gelatinous matrix, X-ray diffraction measurements were performed both on the neat gelators and their gels. The results collected show that the properties of the gel phases, like the thermal stability, the self-repairing ability, the resistance to flow as well as the morphology, are dependent on the nature of the anion. Furthermore, bioassays revealed that the obtained diimidazolium organic salts possessed antimicrobial activity, against gram-negative and gram-positive tester strains. In particular and noteworthy, the diimidazolium organic salts exert a bactericidal capability, which was retained even if they are included in the gel phase. Thus, a novel kind of bioactive soft material was obtained that could be fruitfully employed as a non-covalent coating exerting antibacterial capability.

A sustainable procedure for recycling powdered rubber coming from scrap tires (ground tire rubber [GTR]) is proposed as based on the dispersion in polyketone (PK) matrix, obtained in situ by CO/ethylene copolymerization. Three types of catalysts are used operative in solvents of different polarities. The catalyst productivity and the hybrids morphology are evaluated and optimized to final composites features. The obtained products are characterized by scanning electron microscopy, atomic force microscopy, and solvent extractions in order to investigate the occurrence and the extent of interactions between PK macromolecular chains and the GTR components; and their effects on the final properties were tested by differential scanning calorimetry, thermogravimetric analysis, and rheological measurements. For comparison purpose, a composite with GTR included into the matrix through blending is prepared. The results evidenced the key role exerted by the catalyst that, when operative in apolar solvent (able to swell the rubber phase), provides composites with good interfacial adhesion and breaking up of the particles with beneficial effects on final properties particularly thermal features and processability. Copyright © 2014 John Wiley & Sons, Ltd.

The dispersion of organo-layered double hydroxides (O-LDH) in functionalized polyolefins (POs) is investigated. Two different polyethylene matrices (maleic anhydride (MAH) and diethyl maleate functionalized) are tested and a hydrogenated fatty acid modified LDH is used. The attention is focused on evidencing the interaction between the functional groups of the polymer and the O-LDH through FT-IR. Moreover, a combination of solvent fractionation, morphological, and rheological characterizations enables to gain a deeper insight into the structure of these composites. In particular, the formation of bridging bonds between the particles and MAH functionalized macromolecules is assumed, possibly due to the formation of ionic clusters, characteristics of ionomers, with formation of crosslinked/aggregated structures.

Polymer nanocomposites are currently a topic of great interest. The increasing importance they are gaining also in the standpoint of industrial applications, is giving concerns regarding their environmental stability and, in general, their behaviour in outdoor applications, under direct solar irradiation. Papers available in the literature have highlighted the different influences of different nanosized fillers, in particular clay-based nanofillers; however, few data are available regarding other nanosized fillers. Furthermore, the research on polymer nanocomposites has clearly pointed out that the use of compatibilizers is required to improve the mechanical performance and the dispersion of polar fillers inside apolar polymer matrices, especially when complex mechanisms such as intercalation and exfoliation, typical of clay-filled nanocomposites, are involved. In this work, the photo-oxidation behaviour of polypropylene/clay and polypropylene/calcium carbonate nanocomposites containing different amounts of maleic anhydride grafted polypropylene (PPgMA) and subjected to accelerated weathering, was investigated. The results showed significant differences between the two nanofillers and different degradation behaviours in presence of the compatibilizer. In particular, PPgMA modified the dispersion of the nanofillers but, on the other hand, higher amounts proved to lead to the formation of some heterogeneities. Furthermore, PPgMA proved to positively affect the photo-oxidation behaviour by decreasing the rate of formation of the degradation products. © BME-PT.

Poly(lactic acid) (PLA) is melt mixed with polyamide 11 (PA11) to obtain a heat-resistant fully bio-based blend with PLA as the dominant component. The goal is achieved by adding small amounts of organoclay (OMMT), which is used to manipulate the blend microstructure. The selective positioning of the OMMT inside the PA11 and at the PLA/PA11 interface turns the blend morphology from drop/matrix into co-continuous at high PLA content (70 wt%). The OMMT-rich PA11 framework that interpenetrates the major PLA phase effectively contributes to bear stresses, and the nanocomposite blend keeps its structural integrity up to ≈160 °C, i.e., about 100 °C above the PLA glass transition.

In this work, the thermo- and photo-oxidation stability of functional nitroxide grafted polyethylene (PE) samples was tested. TEMPO derivatives bearing hydroxyl, benzoyl, 1-naphthoyl, and a hindered phenol group as substituents were covalently grafted on the polymer chains by nitroxide radical coupling (NRC) reaction carried out in the melt using a peroxide as a radical initiator. The method enabled polymer crosslinking to be limited and the number of grafted groups to be tuned. The antioxidant behavior of the dual-functionalized PE samples (the alkoxyamine group in quasi-equilibrium with the nitroxide radical, and the functional group attached to the 4-position of the TEMPO ring) was evaluated determining the oxidation induction time (OIT) via DSC measurements and monitoring the carbonyl index via FT-IR before and after thermal and UV aging. The results evidenced only a partial resistance towards the photo-oxidation, whereas the samples functionalized with the hindered phenol substituted TEMPO showed improved thermal oxidation stability.

Multi-functional trisilanol phenyl (TSPH) and trisilanol isobutyl (TSIB) polyhedral oligomeric silsesquioxane (POSS) have been used in the formulation of advanced polystyrene (PS)-zinc oxide (ZnO) nanocomposites. The neat matrix and PS/ZnO-based nanocomposites have been characterized through rheological, morphological, mechanical, and dynamic thermo-mechanical analysis. Both TSPH and TSIB are able to improve the dispersion of ZnO into the polystyrene matrix; furthermore, adding TSIB leads to better results because it facilitates better solubility into the PS matrix and interaction/reaction with the ZnO nanopowder. Finally, the optical properties and photo-oxidative resistance of the nanocomposite films have been evaluated. The POSS molecules synergistically interact with ZnO nanopowder in the protection of PS matrix against photo-oxidative process. The nanocomposite films containing both ZnO and POSS molecules, particularly TSIB, exhibit better UV-shielding properties than the PS/ZnO one, without loss of optical transparency.

Functionalized poly(butylene succinate) (PBS) samples were prepared by a post-polymerization method based on the coupling reaction between TEMPO derivatives bearing different functionalities and PBS macroradicals generated by H-abstraction using a peroxide. 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine-1- oxyl (BzO-TEMPO) and 4-(1-naphthoate)-2,2,6,6-tetramethylpiperidine-1-oxyl (NfO-TEMPO), a pro-fluorescent nitroxide, were successfully grafted on PBS, as revealed by MALDI TOF MS and UV-Vis spectroscopy. The functionalization degrees were accurately determined by UV-Vis analysis and confirmed by 1H-NMR spectroscopy. The grafting site was identified by combining theoretical calculations with experimental evidence. This evidence was collected by both EPR analysis of a functionalized sample subjected to controlled heating in the EPR cavity, and by 1H-NMR spectroscopy. Our functionalization method, which was also tested for poly(lactic acid) (PLA), preserves the original polymer structure. This avoids the crosslinking-branching side reaction, which generally affects the free radical treatment of biodegradable aliphatic polyesters. In addition, using a pro-fluorescent nitroxide to form functionalized samples is a significant step towards unambiguously demonstrating the radical grafting on these types of polymer. It also proves that well-defined fluorescently labeled biodegradable polyesters can be tailored.