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Retrieving the starting monomer from polymers synthesized by reversible deactivation radical polymerization has recently emerged as an efficient way to increase the recyclability of such materials and potentially enable their industrial implementation. To date, most methods have primarily focused on utilizing high temperatures (typically from 120 °C to 180 °C) to trigger an efficient depolymerization reaction. In this work, we show that, in the presence of Eosin Y under light irradiation, a much faster depolymerization of polymers made by reversible addition-fragmentation chain-transfer (RAFT) polymerization can be triggered even at a lower temperatures (i.e. 100 °C). For instance, green light, in conjunction with ppm amounts of Eosin Y, resulted in depolymerization acceleration of poly(methyl methacrylate) from 16% (thermal depolymerization at 100°C) to 37% within 1 hour, and a final 80% of depolymerization after 8 hours, as confirmed by both 1H-NMR and SEC analysis. The enhanced depolymerization rate was attributed to the activation of the macroCTA from Eosin Y, thus resulting in a faster macroradical generation. Notably, this method was found to be compatible with different wavelengths (e.g. blue, red and white irradiation), solvents, and RAFT agents, thus highlighting the potential of light to significantly improve current depolymerization approaches., Polymer Chemistry, 14 (3), ISSN:1759-9962, ISSN:1759-9954

Lithium metal batteries (LMBs) will be a breakthrough in automotive applications, but they require the development of next-generation solid-state electrolytes (SSEs) to stabilize the anode interface. Polymer-in-ceramic PEO/TiO

The synthesis of hydrogels that are based on poly-hydroxyethyl methacrylate, p(HEMA), network semi-interpenetrated with linear polyvinylpyrrolidone (PVP) was optimized in order to allow both a fast preparation and a high cleaning effectiveness of artistic surfaces. For this purpose, the synthesis parameters of the gel with PVP having a high molecular weight (1300 kDa) that were reported in the literature, were modified in terms of temperature, time, and crosslinker amount. In addition, the gel composition was modified by using PVP with different molecular weights, by changing the initiator and by adding maleic anhydride. The modified gels were characterized in terms of equilibrium water content (EWC), water uptake, conversion grade, and thermal properties by differential scanning calorimetry (DSC). The cleaning effectiveness of the gels was studied through the removal of copper salts from laboratory-stained specimens. Cleaning materials were characterized by electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and inductively-coupled plasma-mass spectrometry (ICP-MS). Cleaning was assessed on marble specimens by color variation measurements. The gel synthesis is accelerated by using PVP 360 kDa. The addition of maleic anhydride in the p(HEMA)/PVP network allows the most effective removal of copper salt deposits from marble since it acts as a chelator towards copper ions.

We present an experimental approach to studying the kinetics of polymer nanoparticle formation using molecular rotor molecules as fluorescence probes. By combining fluorescence lifetime analysis and fluorescence correlation spectroscopy, it is possible to simultaneously monitor the evolution of the local environment in the nanoparticles and their size. To assess the generality of the method, we select two common but very different methods for nanoparticle preparation: emulsion-solvent evaporation and miniemulsion polymerization. In both cases, three stages of the nanoparticle formation process were identified on the basis of their polymer content. In the initial stage of the process, the polymer content is low. Then it increases rapidly because of solvent evaporation or polymerization during the second stage. Finally, it reaches a plateau value. Furthermore, significant heterogeneities in the final nanoparticles were found that can be attributed to remaining solvent or monomer and the spatial variation of the polymer-free volume.

Water-in-salt solutions, i.e. solutions in which the amount of salt by volume or weight is larger than that of the solvent, are attracting increasing attention in electrochemistry due to their distinct features that often include decomposition potentials much higher than those of lower concentration solutions. Despite the high solubility of potassium acetate (KAC) in water at room temperature (up to 25 moles of salt per kg of solvent), the low cost, and the large availability, the use of highly concentrated KAC solutions is still limited to a few examples in energy storage applications and a systematic study of their physical-chemical properties is lacking. To fill this gap, we have investigated the thermal, rheological, electrical, electrochemical, and spectroscopic features of KAC/water solutions in the compositional range between 1 and 25 mol kg-1. We show the presence of a transition between the "salt-in-solvent" and "solvent-in-salt" regimes in the range of 10-15 mol kg-1. Among the explored compositions, the highest concentrations (20 and 25 mol kg-1) exhibit good room temperature conductivity values (55.6 and 31 mS cm-1, respectively) and a large electrochemical potential window (above 2.5 V).

The development of mulch films from wastes of vegetables represents a sustainable alternative to the traditionally used polyethylene ones that follow the principles of circular economy. In this work, we obtained films based on two different industrial vegetable wastes, orange peels (OP) and spinach stems (SS), using hydrolysis at different times (6, 16, and 24 h) and temperatures (30, 50, and 70 °C). Hydrolysis carried out at 30 °C and 24 h has led to films with the best mechanical properties, while high temperatures (70 °C) combined with prolonged treatment times (16 and 24 h) led to materials with lower mechanical resistance and darker coloration. The films' characterization by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and uniaxial tensile tests elucidated their chemical structure and physicochemical properties. Additionally, the materials' interaction with water was evaluated and significantly improved by adding a carnauba wax coating. Optical properties, micro and macronutrient content and biodegradation in the soil of selected bioplastics were also determined. Results showed that the proposed materials present fast in-soil biodegradation, good potentiality for weed prevention and improvement of plant growth via soil fertilization.

The effectiveness of Agar gels for copper stain removal from marble surfaces was systematically studied. Gels with different agar concentrations (1, 3, 5%) and different chelating agents used as additives (ethylenediaminetetraacetic acid, EDTA, and ammonium citrate tribasic, TAC) were tested on laboratory marble specimens for different contact times (30 and 60 min). For better characterization, hydrogels were lyophilised and cryogels were obtained. Systematic comparison of different formulations was feasible on cryogels and performed in terms of: (i) the morphological properties, by field-emission scanning electron microscopy (FE-SEM); (ii) the type of Cu(II)-complexes formed and their quantitative comparison by electron paramagnetic resonance (EPR) spectroscopy; (iii) the total amount of copper removed from marble surfaces, by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). AgarArt 1% with TAC exhibited the highest effectiveness for copper stain removal after 60 min contact (431 μg/cm2). Such a good cleaning effectiveness can be ascribed to the co-presence of the following properties: efficient metal coordination, which is related to the additive presence, and favourable gel morphology, related both to the gel concentration and to the additive type. In fact, it was observed that both the low gel concentration and the presence of TAC are related to a narrow pore size distribution in gels, besides the possibility of copper coordination. The presence of EDTA results in a broader pore size distribution and in a lower gel strength, with respect to gels with TAC. Thus, a new procedure for studying gels was proposed, which allows to optimize the conditions for metal stain removal from built heritage.

The design and development of contrast agents (CAs) for magnetic resonance imaging (MRI) in clinical analysis is expected to improve the image spatial resolution and to increase the detection sensitivity, especially regarding neurological disorders and cancer disease. In particular, advanced CAs for T1-weighted images are investigated to achieve the sensitive detection of early-stage primary tumors or brain metastases. In this study, we present a strategy toward diagnostic T1 CAs for MRI, based on polymer-modified MnO nanoparticles (NPs). Two different nanosystems were synthesized, consisting of (1) colloidal MnO nanocrystals wrapped by a multidentate amphiphilic polymer and (2) MnO nanocrystals embedded within poly(lactic-co-glycolic acid) (PLGA) NPs. These nanosystems were compared in terms of their MRI contrast power and biological safety. The latter system combines the excellent biocompatibility of PLGA with the unique magnetic properties of MnO NPs and allows sustained contrast enhancement over time. Longitudinal relaxivities of both MnO composite nanomaterials proved to be higher than those of commercial Gd-based CAs and Teslascan, both in phosphate-buffered saline and in plasma, also exhibiting low cytotoxicity. The high relaxation rates achieved with these contrast enhancers are promising toward future application in in vivo imaging.

The localization of the rubber vulcanization reaction close to the silica filler surface was investigated in isoprene rubber composites (IR NCs): the main goal was to highlight the role of curing agents’ dispersion and filler surface features on the spatial propagation of the rubber cross-links and the resulting mechanical behavior of the material. The study was realized by tailoring the morphology of the curing activator, i.e. by vulcanizing IR NCs with Zn@SiO2 double function filler, composed of Zn(II) single sites anchored on SiO2 filler, in comparison to silica filled IR NCs vulcanized with microcrystalline ZnO. The microscopic cross-links distribution was measured by Transmission Electron Microscopy for network visualization (NVTEM) and Time Domain Nuclear Magnetic Resonance (TD-NMR). Besides the NCs mechanical behavior was characterized both at small strain and at fracture. In the presence of Zn@SiO2, higher cross-link density in proximity to SiO2 particles was evidenced, which gradually spreads from the filler surface to the bulk, induced by localization of the Zn(II) centers. IR NCs with Zn@SiO2 resulted stiffer (+45%) and with a lower fracture toughness (less than one third), compared to m-ZnO based NCs, which shows a quite homogeneous structure of the rubber cross-links network. The results highlighted the correlation between the composites structural features and their macroscopic behavior, paving the way to modulating the mechanical properties of elastomeric materials by tuning the nature of the curing agents.

Lithium metal batteries (LMBs) will be a breakthrough in automotive applications, but they require the development of next-generation solid-state electrolytes (SSEs) to stabilize the anode interface. Polymer-in-ceramic PEO/TiO2 nanocomposite SSEs show outstanding properties, allowing unprecedented LMBs durability and self-healing capabilities. However, the mechanism underlying the inhibition/delay of dendrite growth is not well understood. In fact, the inorganic phase could act as both a chemical and a mechanical barrier to dendrite propagation. Combining advanced in situ and ex situ experimental techniques, we demonstrate that oligo(ethylene oxide)-capped TiO2, although chemically inert toward lithium metal, imparts SSE with mechanical and dynamical properties particularly favorable for application. The self-healing characteristics are due to the interplay between mechanical robustness and high local polymer mobility which promotes the disruption of the electric continuity of the lithium dendrites (razor effect).

The dynamics of xenon gas, loaded in a series of 1-alkyl-3-methylimidazolium based ionic liquids, probes the formation of increasingly blurred polar/apolar nanodomains as a function of the anion type and the cation chain length. Exploiting 129 Xe NMR spectroscopy techniques, like Pulse Gradient Spin Echo (PGSE) and inversion recovery (IR), the diffusion motion and relaxation times are determined for 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Cn C1 im][TFSI]. A correlation between the ILs nano-structure and both xenon diffusivity and relaxation times, as well as chemical shifts, is outlined. Interestingly, comparison with previous results of the same properties in the homologous imidazolium chlorides and hexafluorophospate shows an opposite trend with the alkyl chain length. Classical molecular dynamics (MD) simulations are used to calculate the xenon and cation and anion diffusion coefficients in the same systems, including imidazolium cations with longer chains (n=4, 6, 8 … 20). An almost quantitative agreement with the experiments validates the MD simulations and, at the same time, provides the necessary structural and dynamic microscopic insights on the nano-segregation and diffusion of xenon in bistriflimide, chloride and hexafluorphosphate salts allowing to observe and rationalize the shaping effect of the cation in the nanostructure.

Ionic liquid (IL) mixtures enable the design of fluids with finely tuned structural and physicochemical properties for myriad applications. In order to rationally develop and design IL mixtures with the desired properties, a thorough understanding of the structural origins of their physicochemical properties and the thermodynamics of mixing needs to be developed. To elucidate the structural origins of the excess molar volume within IL mixtures containing ions with different alkyl chain lengths, 3 IL mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs have been explored in a joint small angle X-ray scattering (SAXS) and 129Xe NMR study. The apolar domains of the IL mixtures were shown to possess similar dimensions to the largest alkyl chain of the mixture with the size evolution determined by whether the shorter alkyl chain was able to interact with the apolar domain. 129Xe NMR results illustrated that the origin of excess molar volume in these mixtures was due to fluctuations within these apolar domains arising from alkyl chain mismatch, with the formation of a greater number of smaller voids within the IL structure. These results indicate that free volume effects for these types of mixtures can be predicted from simple considerations of IL structure and that the structural basis for the formation of excess molar volume in these mixtures is substantially different to IL mixtures formed of different types of ions.

The formation of block copolymer nanoparticles is commonly obtained by switching solvent quality from good solvent for both blocks to a selective solvent for one block. The effect of the selective solvent on particle dimension, shape and inner structure has been analyzed in detail, instead less attention has been focused on the role of the common solvent. Poly(ethylene oxide)-block-poly(lactic acid) (PEO-b-PLA) is widely used for the preparation of nanometric drug delivery systems and the control of the particle morphology has relevant effects on bioactivity. In this work we investigate the effect of using different common solvents (acetone, dioxane, tetrahydrofuran, dimethylformamide) on the self-assembly behavior of narrowly dispersed PEO-b-PLA copolymers, synthesized by metal free ring-opening polymerization, with large variation of molecular weight of the hydrophobic block (from 65 to 1300 lactic units). Dynamic light scattering (DLS) and cryo-electron microscopy (cryo-EM) analyses of PEO-b-PLA nanoparticles reveal that their size and shape are strongly dependent on the hydrogen bonding ability of the common solvent used in the self-assembly process. As consequence of these variations, also the cytoxicity of the nanoparticles is affected.

Photochemistry has attracted great interest in the last decades in the field of polymer and material science for the synthesis of innovative materials. The merging of photochemistry and reversible-deactivation radical polymerizations (RDRP) provides good reaction control and can simplify elaborate reaction protocols. These advantages open the doors to multidisciplinary fields going from composite materials to bio-applications. Photoinduced Electron/Energy Transfer Reversible Addition-Fragmentation Chain-Transfer (PET-RAFT) polymerization, proposed for the first time in 2014, presents significant advantages compared to other photochemical techniques in terms of applicability, cost, and sustainability. This review has the aim of providing to the readers the basic knowledge of PET-RAFT polymerization and explores the new possibilities that this innovative technique offers in terms of industrial applications, new materials production, and green conditions.

Developing new materials for the separation of gas mixtures is a key subject in setting up a circular economy. In this work, we report the synthesis and application of novel polymeric membranes, based on polymerized ionic liquids (PILs), to be used for CO2 separation from different gas pairs. Phosphonium-based PILs have been copolymerized within an original acrylate formulation that allowed the development of dense membranes able to overcome some of the main limitations related to ionic liquid membranes. Thereby, a collection of phosphonium ionic liquids has been investigated by evaluating the influence of the alkyl chain length and anion type on membrane structure and properties by employing a series of different chemo-physical characterization techniques. The membranes showed a marked preference toward CO2 permeation in the wet state, which simulates the conditions occurring with many CO2-containing gas streams, with two of the studied membranes exceeding the Robeson upper bound for the CO2/H2 gas pair.

The translational dynamics of xenon gas dissolved in room-temperature ionic liquids (RTILs) is revealed by 129Xe NMR and molecular dynamics (MD) simulations. The dynamic behavior of xenon gas loaded in 1-alkyl-3-methylimidazolium chloride, [CnC1im]Cl (n = 6, 8, 10), and hexafluorophosphate, [CnC1im][PF6] (n = 4, 6, 8, 10) has been determined by measuring the 129Xe diffusion coefficients and NMR relaxation times. The analysis of the experimental NMR data demonstrates that, in these representative classes of ionic liquids, xenon motion is influenced by the length of the cation alkyl chain and anion type. 129Xe spin-lattice relaxation times are well described with a monoexponential function, indicating that xenon gas in ILs effectively experiences a single average environment. These experimental results can be rationalized based on the analysis of classical MD trajectories. The mechanism described here can be particularly useful in understanding the separation and adsorption properties of RTILs.

Lithium Metal Batteries (LMB) require solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Polymer-in-ceramic nanocomposites with the ceramic fraction exceeding the one normally used as the filler (>10 ÷ 15 wt%) are among the most interesting options on the table. Here, we report on a new hybrid material encompassing brush-like TiO2 nanocrystals functionalized with low molecular weight poly(ethylene oxide) (PEO). The nanocomposite electrolyte membranes are then obtained by blending the brush-like nanocrystals with high molecular weight PEO and LiTFSI. The intrinsic chemical compatibility among the PEO moieties allows a TiO2 content as high as ∼39 wt% (90:10 w/w functionalized nanocrystals/PEO-LiTFSI), while maintaining good processability and mechanical resistance. The 50:50 w/w nanocomposite electrolyte (18.8 wt% functionalized TiO2) displays ionic conductivity of 3 × 10−4 S cm−1 at 70 °C. Stripping/plating experiments show an excellent long-term behavior even at relatively high currents of 200 μA cm−2. Upon testing in a lab-scale Li/electrolyte/LiFePO4 cell, the material delivers 130 mAh g−1 and 120 mAh g−1 after 40 and 50 cycles at 0.05 and 0.1 mA, respectively, with Coulombic efficiency exceeding 99.5%, which demonstrates the very promising prospects of these newly developed nanocomposite solid electrolyte for future development of LMBs.

Membrane modification is becoming ever more relevant for mitigating fouling phenomena within wastewater treatment applications. Past research included a novel low-fouling coating using polymerizable bicontinuous microemulsion (PBM) induced by UV-LED polymerization. This additional cover layer deteriorated the filtration capacity significantly, potentially due to the observed high pore intrusion of the liquid PBM prior to the casting process. Therefore, this work addressed an innovative experimental protocol for controlling the viscosity of polymerizable bicontinuous microemulsions (PBM) before casting on commercial ultrafiltration (UF) membranes. Prior to the coating procedure, the PBM viscosity modulation was carried out by controlled radical polymerization (CRP). The regulation was conducted by introducing the radical inhibitor 2,2,6,6-tetramethylpiperidine 1-oxyl after a certain time (CRP time). The ensuing controlled radical polymerized PBM (CRP-PBM) showed a higher viscosity than the original unpolymerized PBM, as confirmed by rheological measurements. Nevertheless, the resulting CRP-PBM-cast membranes had a lower permeability in water filtration experiments despite a higher viscosity and potentially lower pore intrusion. This result is due to different polymeric structures of the differently polymerized PBM, as confirmed by solid-state nuclear magnetic resonance (NMR) investigations. The findings can be useful for future developments in the membrane science field for production of specific membrane-coating layers for diverse applications.

The possibility to use the macromolecules present in vegetable biomass, with minimal processing, as alternative materials to produce new green bioplastics for packaging is very appealing. This strategy can help to mitigate environmental issues due to broad usage of conventional plastics. Since a large variety of vegetable waste, in terms of chemical composition and supramolecular organization, is produced by the food industry, many different bioplastics can be produced with the same protocol. Bioplastics films from carrot pomace, cocoa shells, spinach stems and orange peels will be characterized in terms of thermomechanical properties and biodegradability. The mechanical properties will be correlated with the composition and morphology as determined by means of a combination of techniques (solid-state NMR, SEM and confocal microscopy). The biodegradability of the films will be characterized in terms of Biochemical Oxygen Demand as function of time during 30 days of incubation in seawater.

Diels-Alder chemistry has been used for the thermoreversible cross-linking of furan-functionalized ethylene/propylene (EPM) and ethylene/vinyl acetate (EVM) rubbers. Both furan-functionalized elastomers were successfully cross-linked with bismaleimide to yield products with a similar cross-link density. NMR relaxometry and SAXS measurements both show that the apolar EPM-g-furan precursor contains phase-separated polar clusters and that cross-linking with polar bismaleimide occurs in these clusters. The heterogeneously cross-linked network of EPM-g-furan contrasts with the homogeneous network in the polar EVM-g-furan. The heterogeneous character of the cross-links in EPM-g-furan results in a relatively high Youngs modulus, whereas the more uniform cross-linking in EVM-g-furan results in a higher tensile strength and elongation at break.

Upconversion is a photon-management process especially suited to water-splitting cells that exploit wide-bandgap photocatalysts. Currently, such catalysts cannot utilize 95% of the available solar photons. We demonstrate here that the energy-conversion yield for a standard photocatalytic water-splitting device can be enhanced under solar irradiance by using a low-power upconversion system that recovers part of the unutilized incident sub-bandgap photons. The upconverter is based on a sensitized triplet-triplet annihilation mechanism (sTTA-UC) obtained in a dye-doped elastomer and boosted by a fluorescent nanocrystal/polymer composite that allows for broadband light harvesting. The complementary and tailored optical properties of these materials enable efficient upconversion at subsolar irradiance, allowing the realization of the first prototype water-splitting cell assisted by solid-state upconversion. In our proof-of concept device the increase of the performance is 3.5%, which grows to 6.3% if concentrated sunlight (10 sun) is used. Our experiments show how the sTTA-UC materials can be successfully implemented in technologically relevant devices while matching the strict requirements of clean-energy production.

Ionic liquid (IL) mixtures enable the design of fluids with finely tuned structural and physicochemical properties for myriad applications. In order to rationally develop and design IL mixtures with the desired properties, a thorough understanding of the structural origins of their physicochemical properties and the thermodynamics of mixing needs to be developed. To elucidate the structural origins of the excess molar volume within IL mixtures containing ions with different alkyl chain lengths, 3 IL mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs have been explored in a joint small angle X-ray scattering (SAXS) and 129Xe NMR study. The apolar domains of the IL mixtures were shown to possess similar dimensions to the largest alkyl chain of the mixture with the size evolution determined by whether the shorter alkyl chain was able to interact with the apolar domain. 129Xe NMR results illustrated that the origin of excess molar volume in these mixtures was due to fluctuations within these apolar domains arising from alkyl chain mismatch, with the formation of a greater number of smaller voids within the IL structure. These results indicate that free volume effects for these types of mixtures can be predicted from simple considerations of IL structure and that the structural basis for the formation of excess molar volume in these mixtures is substantially different to IL mixtures formed of different types of ions.

Photon upconversion based on sensitized triplet-triplet annihilation (sTTA) is considered as a promising strategy for the development of light-managing materials aimed to enhance the performance of solar devices by recovering unused low-energy photons. Here, we demonstrate that, thanks to the fast diffusion of excitons, the creation of triplet pairs in metal-organic framework nanocrystals (nMOFs) with size smaller than the exciton diffusion length implies a 100% TTA yield regardless of the illumination condition. This makes each nMOF a thresholdless, single-unit annihilator. We develop a kinetic model for describing the upconversion dynamics in a nanocrystals ensemble, which allows us to define the threshold excitation intensity Ith box required to reach the maximum conversion yield. For materials based on thresholdless annihilators, Ith box is determined by the statistical distribution of the excitation energy among nanocrystals. The model is validated by fabricating a nanocomposite material based on nMOFs, which shows efficient upconversion under a few percent of solar irradiance, matching the requirements of real life solar technologies. The statistical analysis reproduces the experimental findings, and represents a general tool for predicting the optimal compromise between dimensions and concentration of nMOFs with a given crystalline structure that minimizes the irradiance at which the system starts to fully operate.

Highly controlled polymers and nanostructures are increasingly translated from the lab to the industry. Together with the industrialization of complex systems from renewable sources, a paradigm change in the processing of plastics and rubbers is underway, requiring a new generation of analytical tools. Here, we present the recent developments in time domain NMR (TD-NMR), starting with an introduction of the methods. Several examples illustrate the new take on traditional issues like the measurement of crosslink density in vulcanized rubber or the monitoring of crystallization kinetics, as well as the unique information that can be extracted from multiphase, nanophase and composite materials. Generally, TD-NMR is capable of determining structural parameters that are in agreement with other techniques and with the final macroscopic properties of industrial interest, as well as reveal details on the local homogeneity that are difficult to obtain otherwise. Considering its moderate technical and space requirements of performing, TD-NMR is a good candidate for assisting product and process development in several applications throughout the rubber, plastics, composites and adhesives industry.

Fluorine-19 (19F)-based contrast agents are increasingly used for magnetic resonance imaging. Conjugated to polymers, they provide an excellent quantitative imaging tool to detect the movement of the polymeric nanoparticles in vivo as there is no background signal in tissue. One of the challenges is the decline in signal intensity when the conjugated hydrophobic fluorinated functionalities aggregate. Therefore, a new fluorinated monomer was prepared from l-arginine that carries a 2,2,2-trifluoroethyl functional group for imaging. The resulting monomer, 2,2,2-trifluoroethylamide l-arginine methacrylamide (3FArgMA), was copolymerized with poly(ethylene glycol) methyl ether methacrylate (PEGMEMA), [2-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyloxy)ethyl methacrylate or 1-O-methacryloyl-2,3:4,5-di-O-isopropylidene-β-d-fructopyranose, respectively, using poly(methyl methacrylate) macro-reversible addition–fragmentation chain transfer polymerization agent. The resulting block copolymers, which varied in 3FArgMA content, were self-assembled into micelles of hydrodynamic diameters from 25 to 60 nm. The permanently positively charged arginine functionality on the 3FArgMA displayed repulsive forces against aggregation enabling high spin–spin relaxation times (T2) in acidic as well as alkaline solutions. However, the longer poly(ethylene glycol) side functionality in PEGMEMA enabled better steric stabilization (T2~30 ms) while the short fructose side chain was not enough to maintain high T2 values, in particular when a higher 3FArgMA content was used. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1994–2001.

Reversible addition-fragmentation chain transfer polymerization of chloroprene on the surface of silica nanoparticles was performed to obtain polychloroprene-grafted-silica nanoparticles (PCP-g-SiO2 NPs). These particles were dispersed in a commercial polychloroprene matrix to obtain PCP nanocomposites with different silica core loadings (1, 5, 10, and 25 wt%). Two different chain graft densities were studied (“low,” 0.022 ch/nm2 and “high,” 0.21 ch/nm2) as a function of the grafted polymer molecular mass. The cured samples showed significant improvement in the mechanical properties of the PCP rubber nanocomposites as compared to the unfilled PCP as measured by standard tensile and dynamic mechanical analysis even with low silica content. The mechanical properties of the nanocomposites were notably enhanced when the graft density was low and grafted molecular masses were high. Transmission electron microscopy (TEM) and Small-Angle X-ray Scattering (SAXS) were used to analyze the dispersion states of the grafted nanoparticles which confirmed the correlation between high grafted chain lengths and improved dispersion states and mechanical properties.

The sensitized triplet-triplet annihilation-based upconversion in bicomponent systems is currently considered the most promising strategy for increasing the light-harvesting ability of solar cells. Flexible, manageable, inexpensive up-converting devices become possible by implementing this process in elastomers. Here, we report a study combining optical spectroscopy data of the light conversion process with the nano- and macroscopic viscoelastic characterization of the host material embedding the active dyes, in order to find a rationale for the fabrication of efficient solid-state upconverting systems. By using the poly(n-alkyl acrylates) as a model of the monophasic elastomers, we demonstrate that the yield of the bimolecular interactions at the base of the upconversion process, namely, energy transfer and triplet-triplet annihilation, is mainly determined by the glass transition temperature (Tg) of the polymer. By employing the polyoctyl acrylate (Tg = 211 K), we achieved a conversion yield at the solid state larger than 10% at an irradiance of 1 sun, showing the potential of the elastomer-based upconverting materials for developing real-world devices.

Micro and mesoporous materials are often used in catalysis, purification, composite filler, and other applications. Almond shell is an important agricultural byproduct that can be transformed to microporous and mesoporous carbon. In this work, we produced biochar from almond shell using a thermal treatment procedure in an inert atmosphere and characterized the pores with nitrogen adsorption, environmental SEM, and 129Xe NMR. The latter technique differentiates adsorbed and nonadsorbed xenon and permits the correlation of different processing conditions with xenon adsorption and diffusivity. The relevance of removing the ash produced during the charring process has been included in the study. Moreover, the xenon exchange between meso- and micro-pores has been directly observed by 129Xe NMR, demonstrating that after ash removal by water the materials have high accessibility of the pores by external fluids, thus increasing the usefulness as filtration or adsorption material.

The possibility to use vegetable biomass, with minimal processing, as new green bioplastic for packaging is very appealing to mitigate environmental issues due to broad usage of conventional plastics. Here we developed vegetable bioplastic films from carrot pomace with good mechanical properties and glass transition temperature function of humidity, with a lowest value of −60 °C when highly hydrated. These properties were exploited to set-up scalable and green fabrication techniques for the production of macroscopic objects with elaborate shapes and detailed features at the micro scale. By means of a combination of techniques (FTIR, NMR, DSC and DMTA) we provide a comprehensive picture of the material structure and how the absorbed water changes the macromolecules’ structure, finally explaining the source of the glass transition of the material.

Nanocrystals (NCs) surface characterization is a fundamental step for understanding the physical and chemical phenomena involved at the nanoscale. Surface energy and chemistry depend on particle size and composition, and, in turn, determine the interaction of NCs with the surrounding environment, their properties and stability, and the feasibility of nanocomposites. This work aims at extracting more information on the surface of different titanium dioxide polymorphs using

Subtle alterations in the mid-block of polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) have a significant impact on the mechanical properties of the resulting microphase separated materials. In samples with high butylene content, the ethylene-co-butylene (EB) phase behaves as a rubber, as seen by differential scanning calorimetry (DSC), time domain (TD) and Magic Angle Spinning (MAS) NMR, X-ray scattering at small (SAXS), and wide (WAXS) angles. In samples where the butylene content is lower&mdash, but still sufficient to prevent crystallization in bulk EB&mdash, the DSC thermogram presents a broad endothermic transition upon heating from 221 to 300 K. TD NMR, supported by WAXS and dielectric spectroscopy measurements, probed the dynamic phenomena of EB during this transition. The results suggest the existence of a rotator phase for the EB block below room temperature, as a result of nanoconfinement.

Shortly after processing, Polyethylene/Polypropylene (PE/PP) multilayer films demonstrate an increase in tensile modulus and other mechanical properties when the individual layer thickness is below 0.5 μm. Subsequent annealing at 60 °C for 16 h brings the properties of all other samples to similar values. WAXD characterization of the layered films identified a prevalence of mesophase in the thicker PP layers. In samples with increased layer numerosity or subjected to annealing, WAXD detected its conversion to α crystalline phase that correlates with improved mechanical properties. SSNMR and DSC detailed the defective nature of α iPP crystallites. Comonomers, detected by NMR in the commercial polymers used for the films, are the source of "tunable disorder" that dictates the formation of the PP mesophase and the low temperature of conversion to the mechanically stronger defective α phase. Soft intrafilm layer interfaces instead enable nucleation and localized polymer chain rearrangement even without annealing

Nanocrystals (NCs) surface characterization is a fundamental step for understanding the physical and chemical phenomena involved at the nanoscale. Surface energy and chemistry depend on particle size and composition, and, in turn, determine the interaction of NCs with the surrounding environment, their properties and stability, and the feasibility of nanocomposites. This work aims at extracting more information on the surface of different titanium dioxide polymorphs using1H-TD-NMR of water. Taking advantage of the interaction between water molecules and titanium dioxide NCs, it is possible to correlate the proton transverse relaxation times (T2) as the function of the concentration and the specific surface area (δp·Cm) and use it as an indicator of the crystal phase. Examples of three different crystals phase, rutile, anatase, and brookite, have been finely characterized and their behavior in water solution have been studied with TD-NMR. The results show a linear correlation between relaxivity (R2) and their concentration Cm. The resulting slopes, after normalization for the specific surface, represent the surface/water interaction and range from 1.28 g m-2s-1of 50 nm rutile nanocrystals to 0.52 for similar sized brookite. Even higher slopes (1.85) characterize smaller rutile NCs, in qualitative accordance with the trends of surface energy. Thanks to proton relaxation phenomena that occur at the NCs surface, it is possible to differentiate the crystal phase and the specific surface area of titanium dioxide polymorphs in water solution.

The valorization of vegetable waste can create opportunities to produce new valuable bioplastics.In thisstudy, a one-step process to fully convert a variety of vegetable waste materials into bioplasticfilms is reported. The process is carried out in a diluted aqueous HCl solution at room temperature,it is easily scalable, and with no environmental concerns associated with the use of organic ordangerous chemicals. The generated bioplastics arecompletely biodegradable and environmentallyfriendly. Freestanding, flexible bioplastic films were obtained from vegetable waste like carrot,parsley, radicchio and cauliflower. They have similar mechanical properties with other bioplastics, like thermoplastic starch, and showed to have little migration in a food simulant. The color andthe functional properties (i.e. antioxidant capability) of the starting vegetables are preserved inthe bioplastics, thanks to the mild conditions of the fabrication process. The new conversionprocess allows the blending of the bioplastics with other natural or synthetic polymers, in order to improve their mechanical and gas barrier properties, like the oxygen permability (OP), thusexpanding their field of applications. Poly vinyl alcohol (PVA)/carrot bioplastic film showed an OPof 31.2 cm3 μm m−2 day−1 kPa−1, which is lower than the OP for other synthetic films, like highdensity polyethylene films (HDPE), and similar to edible materials like chitosan. &nbsp

Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an important element in net zero energy consumption buildings of the future. Colloidal quantum dots are promising materials for luminescent solar concentrators as they can be engineered to provide the large Stokes shift necessary for suppressing reabsorption losses in large-area devices. Existing Stokes-shift-engineered quantum dots allow for only partial coverage of the solar spectrum, which limits their light-harvesting ability and leads to colouring of the luminescent solar concentrators, complicating their use in architecture. Here, we use quantum dots of ternary I-III-VI 2 semiconductors to realize the first large-area quantum dot-luminescent solar concentrators free of toxic elements, with reduced reabsorption and extended coverage of the solar spectrum. By incorporating CuInSe x S 2-x quantum dots into photo-polymerized poly(lauryl methacrylate), we obtain freestanding, colourless slabs that introduce no distortion to perceived colours and are thus well suited for the realization of photovoltaic windows. Thanks to the suppressed reabsorption and high emission efficiencies of the quantum dots, we achieve an optical power efficiency of 3.2%. Ultrafast spectroscopy studies suggest that the Stokes-shifted emission involves a conduction-band electron and a hole residing in an intragap state associated with a native defect.

In the search of new drug delivery carriers for the brain, self-assembled nanoparticles (NP) were prepared from poly(N,N-dimethylacrylamide)-block-polystyrene polymer. NP displayed biocompatibility on cultured endothelial cells, macrophages and differentiated SH-SY5Y neuronal-like cells. The surface-functionalization of NP with a modified fragment of human Apolipoprotein E (mApoE) enhanced the uptake of NP by cultured human brain capillary endothelial cells, as assessed by confocal microscopy, and their permeability through a Transwell Blood Brain Barrier model made with the same cells, as assessed by fluorescence. Finally, mApoE-NP embedding doxorubicin displayed an enhanced release of drug at low pH, suggesting the potential use of these NP for the treatment of brain tumors.

Building-integrated photovoltaics is gaining consensus as a renewable energy technology for producing electricity at the point of use. Luminescent solar concentrators (LSCs) could extend architectural integration to the urban environment by realizing electrode-less photovoltaic windows. Crucial for large-area LSCs is the suppression of reabsorption losses, which requires emitters with negligible overlap between their absorption and emission spectra. Here, we demonstrate the use of indirect-bandgap semiconductor nanostructures such as highly emissive silicon quantum dots. Silicon is non-toxic, low-cost and ultra-earth-abundant, which avoids the limitations to the industrial scaling of quantum dots composed of low-abundance elements. Suppressed reabsorption and scattering losses lead to nearly ideal LSCs with an optical efficiency of η = 2.85%, matching state-of-the-art semi-transparent LSCs. Monte Carlo simulations indicate that optimized silicon quantum dot LSCs have a clear path to η > 5% for 1 m2 devices. We are finally able to realize flexible LSCs with performances comparable to those of flat concentrators, which opens the way to a new design freedom for building-integrated photovoltaics elements. Reabsorption losses in luminescent solar concentrators can be avoided by the use of indirect-bandgap semiconductor nanostructures. The technology has been used to demonstrate flexible luminescent solar concentrators with performance comparable to flat concentrators.

Super paramagnetic iron oxide nanoparticles (SPION) were augmented by both hyaluronic acid (HA) and bovine serum albumin (BSA), each covalently conjugated to dopamine (DA) enabling their anchoring to the SPION. HA and BSA were found to simultaneously serve as stabilizing polymers of Fe₃O₄·DA-BSA/HA in water. Fe₃O₄·DA-BSA/HA efficiently entrapped and released the hydrophobic cytotoxic drug paclitaxel (PTX). The relative amount of HA and BSA modulates not only the total solubility but also the paramagnetic relaxation properties of the preparation. The entrapping of PTX did not influence the paramagnetic relaxation properties of Fe₃O₄·DA-BSA. Thus, by tuning the surface structure and loading, we can tune the theranostic properties of the system.