The cold sintering process (CSP) was employed at room temperature to consolidate dolostone powders and dolostone-matrix composites containing a dispersed organic phase for near-room temperature thermal energy storage. The materials' microstructure and structure were thoroughly analyzed, and their mechanical and thermal properties were assessed. The results show that the composite's density increases with CSP pressure and bending strength (up to about 10-12 MPa). These composites exhibit a thermal energy storage capacity of approximately 15 J g-1 at near-room temperature, thanks to the latent heat of fusion/crystallization of the organic phase (i.e., the phase change material, PCM). Specific care needs to be taken in choosing the PCM, as it could cause unwanted interactions with the CSP solution. The developed process offers a new approach for manufacturing sustainable materials with low embodied energy and thermal management capabilities.

This study investigates the impact of clinically relevant sterilization methods, such as ethylene oxide (EtO), gamma (γ) irradiation, autoclaving, and hydrogen peroxide gas plasma, on the physical, structural, and functional properties of methacrylated silk fibroin hydrogels obtained by photo- and enzymatic crosslinking. EtO, γ irradiation, and hydrogen peroxide gas plasma were applied as terminal sterilization methods to the fabricated hydrogels, whereas autoclaving was performed on the SilMA precursor solution prior to hydrogel formation. Silk fibroin hydrogels at 5 and 7 wt.% concentrations were evaluated for transparency, rheological behavior, water content, secondary structure, chemical composition, thermal stability, microbial growth, and morphology after sterilization and during storage. EtO sterilization effectively maintained high optical transparency (>98%) but compromised the mechanical properties of the hydrogels. In contrast, γ-irradiation and autoclaving promoted greater β-sheet formation, resulting in increased mechanical stiffness and thermal stability but reduced transparency after autoclaving. Plasma sterilization proved unsuitable, as incomplete cycles related to the high-water content of hydrogels. Overall, the results delineate the influence of different sterilization strategies and identify approaches that best preserve or enhance the performance of silk hydrogels, supporting their clinical translation in tissue engineering.

The efficiency of the sulfur cross-linking in rubber is enhanced by zinc-based activators. Zn(II) centers are formed by the interaction of microcrystalline ZnO with fatty acids and generate reactive zinc-based organic complexes through the reaction with the accelerator and sulfur. Despite ZnO is the most used industrial activator, several efforts have been made to find more sustainable alternatives, by reducing the zinc content and the zinc leaching during the lifecycle of rubber products. Among them, a promising candidate recently proposed is composed of Zn (II) single sites anchored onto the surface of silica nanoparticles. This material has proven good curing efficiency, thanks to a good zinc reactivity towards the curing agents and high availability to form active Zn(II) complexes. In this context, the present study deeply investigates the reactivity of the Zn(II) single sites by modifying the zinc coordination onto the silica surface, through the introduction of five surface ligands (L) producing Zn-L-SiO2 curing activators. These were synthesized by using amino, carboxyl and sulfur-based terminated ligands, to promote different coordination geometry in the Zn(II) coordination sphere. This strongly impacts on the reactivity of Zn(II)-based activators tested during the sulfur curing process, paving the way for their fine tailoring.

The rapid development of semiconductor and electronics industries have urged novel adsorbents for fluoride removal from wastewater. In this study, we developed a metal-organic framework filter by in-situ implanting MIL-96(Al) onto Al mesh, which demonstrated effective and stable fluoride removal over a wide range of pH (3-11). The solid state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) results revealed that the different structural changes to which Al3 sites are subjected upon pH modifications trigger fluoride adsorption through Lewis interactions at acidic pH values and through ligand exchange mechanism at neutral/alkaline pH values. Moreover, the filter demonstrated limited Al ions leakage and satisfactory adsorption selectivity towards fluoride among chloride, nitrate, and sulfate, at concentrations up to 50-times higher than fluoride. As a proof of concept for practical applications, the developed filters were sealed in tandem into a homemade filter holder and tested for fluoride removal from real industrial wastewater. When 12 filters were used, fluoride concentrations decreased from 5.8 mg/L to below 1.5 mg/L after 10 min of hydraulic retention time in the filter holder over 5 consecutive cycles. We hope this work may provide new insights for the design of novel adsorbents for fluoride removal.

The growing demand for portable and wireless electronic devices, along with the necessity to reduce reliance on non-renewable energy sources, has driven the need for energy harvesting materials. Nanocomposites, combining a polymeric matrix and a high-performance dielectric ceramic phase, are a promising solution. In such systems, the design of a hybrid matrix-filler interface is critical for achieving desired properties. Here, nanocomposites (NCs) were prepared by adding various amounts of hydrothermally synthesized BaTiO3 (BT) nanoparticles (NPs) to polydimethysiloxane (PDMS). To investigate hybrid interfaces, NPs were used either bare or surface-functionalized with two silanes, 3-glycidyloxypropyltrimethoxysilane (GPTMS) or 2-[acetoxy(polyethyleneoxy)propyl]triethoxysilane (APEOPTES). NC films (80-100 mu m thick) were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and thermogravimetric analysis (TGA). Dielectric properties and breakdown strength (E-BD) were measured, and the theoretical volumetric energy density was calculated as a function of the filler loading and functionalization. The results demonstrate that hybrid interface design is pivotal for enhancing dielectric performance in NCs. APEOPTES-functionalized NPs significantly improved the dielectric response at a low filler loading (3.5%vol.), increasing permittivity from 2.8 to 7.5, E-BD from 33.8 to 42.1 kV/mm and energy density from 30 to >100 mJ/cm(3). These findings underscore that designing hybrid interfaces through NP functionalization provides an effective strategy to achieve superior dielectric performance in PDMS-based NCs, retaining the advantages of the elastomeric matrix by reducing the amount of ceramic fillers.

Polymer-ceramic piezoelectric composites are widely investigated to combine the high piezoelectric performance of ferroelectric ceramics with the flexibility and processability of electroactive polymers. However, achieving enhanced dielectric properties while preserving the intrinsic piezoelectric response of the polymer matrix remains challenging, particularly due to dielectric mismatch between the constituent phases and interfacial effects. In this work, barium titanate (BaTiO3) loaded poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) nanocomposites were fabricated by solvent casting using polyvinylpyrrolidone (PVP) and polysorbate 80 (PS80) as dispersing agents, aiming to obtain polarizable materials capable of retaining high piezoelectric strain coefficient (d(33)) values and potentially exploiting the opposite polarity of matrix and filler through tailored poling strategies. Morphological, crystallographic, structural, thermal, thermomechanical, dielectric, and piezoelectric characterizations were performed by SEM/EDXS, XRD, FTIR, DSC, TGA, DMTA, dielectric spectroscopy, and d(33) measurements. Both dispersants improved filler dispersion and film densification, increasing the crystalline fraction of the matrix, without altering the relative fraction of beta-phase (up to 93%). PVP enabled moderate and stable permittivity enhancement with weak frequency dependence, whereas PS80 introduced an electrically active interfacial contribution that amplified low-frequency permittivity at high filler loadings but made the permittivity more frequency-dependent. The piezoelectric response (between -20 pC/N and -25 pC/N) remained predominantly governed by the polymer phase, suggesting limited polarization played by BaTiO3. These results underlined the critical role of interfacial electrical properties in designing stable high-performance flexible PVDF-TrFE/BaTiO3 composites.

Self-healing hydrogels (SHHs) are promising materials in tissue engineering due to their ability to mimic the biomechanical properties of biological tissues and autonomously repair damage and can serve as ideal three-dimensional scaffolds for cell proliferation and differentiation. However, conventional processing methods, such as extrusion-based printing, often limit the complexity and resolution of the fabricated structures. VAT photopolymerization, particularly digital light processing (DLP), on the other hand, offers advantages in terms of resolution, printing speed, and design freedom, making it an attractive approach for developing SHHs. This study aims to develop a biocompatible and self-healing hydrogel through DLP, enhancing the structural complexity while maintaining self-repairing properties. The hydrogel is made from polyethylene glycol diacrylate (PEGDA), hydroxyethyl methacrylate (HEMA), dithiothreitol (DTT), and borax, and the solvent is PBS. Cross-linking occurs by radical photopolymerization, in which PEGDA and HEMA serve as cross-linkable monomers, while DTT and borax form borate-ester bonds, imparting self-repairing properties. Complex 3D structures were fabricated by using a commercial DLP printer, and self-healing properties were assessed. Chemical (FTIR, NMR), rheological, and mechanical analyses were performed along with cytocompatibility tests. The hydrogel exhibited successful 3D printability, allowing the fabrication of complex structures. Self-healing tests demonstrated that, after 72 h, the samples could self-repair and withstand tensile forces, maintaining their integrity after multiple damage-repair cycles. Chemical and mechanical characterization confirmed the stability and viscoelastic behavior of the material, while preliminary cytocompatibility assays indicated the suitability for tissue engineering applications. DLP-based printing enables the fabrication of self-healing hydrogels with improved resolution and design freedom. The developed hydrogel exhibits promising mechanical properties and biocompatibility, making it a strong candidate for tissue engineering applications.

The effective degradation of persistent aqueous pollutants, such as fenitrothion (FNT), a widely used organophosphate pesticide, represents a major urgency for the protection of human health and the environment. In this regard, this study is focused on the fabrication of green photoelectrocatalysts based on graphitic carbon nitride (gCN), capable of generating hydrogen peroxide (H2O2) to trigger electro-Fenton processes for FNT degradation. In particular, electrophoretic deposition of gCN onto carbon cloth (CC) substrates was performed starting from gCN powders designed via thermal condensation of urea mixed with acetylacetone (AcAc). The resulting defect engineering promoted an improved gCN light harvesting capability and an enhanced separation of photogenerated charge carriers. The obtained supported materials featured an attractive electrochemical reactivity and operational stability, opening the door to their possible real-world end-use. The present work illustrates, as a proof-of-concept, the potential of gCN-based photoelectrocatalysts in water treatment technologies, offering a sustainable solution in a greener perspective to mitigate the environmental impact of hazardous pollutants.

A novel starch-based ether bearing cinnamyl functionalities, conferring photo-crosslinking properties, is synthesised by reaction with cinnamyl chloride in the presence of sodium hydroxide. Natural yuca was selected as a sustainable source of starch. Three different molar equivalents of reagents are used, affording starch-cinnamyl ethers with different degrees of substitution, ranging from 0.09 to 1.24, as determined by liquid phase nuclear magnetic resonance (NMR). The double bonds in the cinnamyl moieties show reactivity towards photodimerization upon irradiation at 254 nm, affording a novel cross-linked bio-inspired polymer. The formation of the covalent ether linkage and the [2+2] cycloaddition of the cinnamyl units are confirmed by a combination of spectroscopic techniques, including solid state NMR. The materials are further characterized by gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and X-ray diffraction analysis (XRD). Starch-cinnamyl ethers with a DS of 0.09 are water soluble, and suitable for the preparation of transparent films potentially exploitable for biodegradable packaging materials.

Two silicate float glasses were considered in the present work: a typical clear soda lime silicate glass and a soda magnesia silicate glass. Both materials underwent chemical strengthening in KNO3, and a different behavior was pointed out in terms of potassium penetration and corresponding surface compression. The soda magnesia silicate glass demonstrated a significantly higher propensity for reinforcement through the exchange of sodium with potassium owing to a much higher interdiffusion coefficient, although the activation energy for the process was substantially identical for the two materials. The difference in performance in terms of Na/K exchange can be only partially correlated to the slightly larger amount of sodium in the soda-magnesia silicate glass, which is instead characterized by a more open structure, richer in five-, six-membered or larger rings, as revealed by NMR and FT-IR/micro-Raman spectroscopy. This structural difference appears to be dictated by the chemical composition of the glasses, soda magnesia silicate material being richer in network formers such as silica, alumina, and, very likely, magnesia, which causes the presence of more abundant Q 3 units and more limited Q 2 and Q 4 ones for a faster movement of the alkaline atoms within the structure.

The potential of ladder-like polysilsesquioxanes (LPSQs) combined with thermally conductive fillers for developing nanocomposites (NCs) with enhanced thermal conductivity (TC) has recently gained interest. While early studies emphasize the importance of controlling ladder-filler interactions, the role of the hybrid interface on interfacial thermal resistance and TC remains underexplored. To address this gap, novel photocurable NCs were developed by incorporating Al2O3 nanoparticles (NPs) functionalized with methacrylate (MA) or amino (AA) groups into LPSQs bearing methacrylate and phenyl side chains. Characterizations revealed that methacrylate conversion and crosslinking significantly affect TC. Furthermore, the nature of covalent and non-covalent interactions at the ladder-filler interface influences both LPSQs structural organization and NCs thermal behavior. Among unfilled matrices, methacrylate-rich polysilsesquioxane (LPMASQ) displays the highest TC due to effective crosslinking. MAPSQ(46), with a 40/60 methacrylate-to-phenyl ratio, shows slightly lower TC, where reduced polymerization was offset by it-it stacking that promotes heat transfer. The introduction of MA NPs improves TC in all systems, particularly in LPMASQ, where copolymerization with the matrix reduces interfacial thermal resistance. Conversely, AA NPs, with lower dispersibility and weaker interactions, affect chain organization in LPMASQ, introducing phonon scattering and lowering TC. However, in mixed LPSQs like MAPSQ(64), with a 60/40 methacrylate-to-phenyl ratio, amino groups enhance thermal diffusivity, suggesting that weak interactions can be beneficial in matrices with limited polymerization. These results underscore the critical role of tuning both LPSQs side chain composition and NPs surface functionalization to balance interfacial interactions and maximize thermal performance in polymer NCs for advanced thermal management applications.

The present study proposes an original approach to obtain silica and silicates decorated with guanidinium groups to be exploited as potential platform for the generation of thermoresponsive solvent-free nanofluids (SFNs). In detail, an alkoxysilane bearing guanidinium functionalities (GuPTES) has been carefully synthesized and then used for the surface functionalization of SiO2 nanoparticles and sepiolite nanofibers, thus generating a positively charged corona layer. Upon careful characterization in terms of grafting density of the silylated guanidinium derivative, the functionalized fillers (SiO2@GuPTES and SepOH@GuPTES) were then modified by a polyethylene glycol provided with anionic sulfonate groups (sulfo-PEG) and acting as canopy, thus obtaining a SFN. The resulting composite materials were characterized by FTIR, TGA, DSC and, particularly, by Time Domain-NMR. Experimental data revealed the presence of structural constraints associated with the formation of ionic interactions between the guanylated surface of the filler and the sulfo PEG group of the polymer chains, which impart temperature-responsive properties, envisaging the promising application of SiO2@GuPTES and SepOH@GuPTES based SFNs as smart solvent-free lubricants.

Starch was plasticized with epoxidized soybean oil (ESO) modified by reaction with cinnamic acid (CA), and films were prepared using solvent casting from water/ethanol solutions. They exhibited good hydrophobicity, reduced water sensitivity, and showed the same transparency as glycerol-plasticized counterparts, but with less flexibility. Interestingly, modified ESO enhanced gelatinization and hindered retrogradation of the biopolymer. ESO was reacted with CA without the use of catalysts to obtain a β-hydroxyester; in order to optimize the synthesis process, different reaction conditions were explored, varying the stoichiometry and the heating cycles. Products were fully characterized by Fourier transform infrared (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR), and the different reactions following the opening of the oxirane ring were discussed. The properties of the novel starch-based films prepared with modified ESO highlight their use in food packaging, disposable devices, and agricultural mulching films.

The miniaturization and high-power density of modern electronic devices pose significant thermal management issues, particularly affecting their performance and lifetime. Ladder-like polysilsesquioxanes (LPSQs) offer a promising solution due to their remarkable thermal, mechanical, and chemical properties. By incorporating thermally conductive fillers, LPSQ composites can achieve high thermal conductivity (TC), making them ideal for thermal management in advanced electronic applications. In this study, LPSQ-based nanocomposites containing functionalized alumina nanoparticles were prepared by solution casting and UV curing, and the effects of varying amounts of Irgacure-184 photoinitiator on their structural and thermal properties were investigated. Three sets of samples were prepared with a fixed amount of LPSQs, 80 wt.% of nanoparticles, and 1, 5, or 10 wt.% of photoinitiator with respect to the matrix. TC was evaluated from the measured values of heat capacity, density, and thermal diffusivity. TC values increased by 60%, 71.2%, and 93.1% for the three samples, respectively, compared to the neat matrix. Results indicate that an intermediate amount of photoinitiator (5%) preserved LPSQs’ structural integrity, namely the presence of long linear silsesquioxane chains, and provided good filler dispersion and distribution, high polymerization degree, thermal stability, and high TC.

A multifunctional alumina-based filler, Al2O3@APTES-Zn, has been synthesized by functionalizing Al2O3 nanoparticles with aminopropyl triethoxysilane (APTES) and subsequently anchoring Zn2+ centers. This multifunctional nanofiller acts simultaneously as a reinforcing agent, cross-linking promoter, and thermal conductivity enhancer in carboxylated nitrile rubber (XNBR) composites. The anchored Zn(II) sites also provide ionic interactions with XNBR terminations, enabling dynamic reversible bonds for self-healing properties. The comprehensive characterization of XNBR/Al2O3@APTES-Zn composites unveils enhanced cross-linking, improved tensile strength and strain at break (up to 17 MPa and 1416% at 24 phr filler), increased thermal conductivity (+11.4% compared to neat Al2O3 at the same loading), and superior self-repairing efficiency (up to 120%). These results demonstrate that the tailored surface and interfacial properties of Al2O3@APTES-Zn represent a promising benchmark for resilient and sustainable composites in applications, such as hoses, seals, gaskets, and automotive components.

A commercial TiO2 sample, used as received or hydrothermally treated to increase surface hydroxylation, has been functionalized by surface modification with hexadecyltrimethoxysilane. The anchoring of the silane has been characterized by means of FTIR and solid-state NMR spectroscopies, and the grafting density was determined by thermogravimetric and N2 physisorption analyses. The silane moieties induce a partial decrease of the shielding of the valence electrons of the Ti ions at the surface, and a local modification of their crystal field, as demonstrated by XPS and UV/Vis spectroscopy, respectively. The changes in coordination and the produced oxygen vacancies result in the formation of Ti3+ defects localized in the sub-surface region, as revealed by EPR spectroscopy. These paramagnetic centers are stabilized in the silanized samples, as the electron transfer to O2 is efficiently inhibited even under UV irradiation. However, the amount of Ti3+ centers appears to be correlated with the singlet oxygen (1O2) formation rate. Accordingly, epoxidation of limonene under UV light, chosen as a model photocatalytic reaction triggered by 1O2, occurred with higher selectivity when TiO2 was silanized and upon simultaneous NIR irradiation. These evidences suggest that in the silanized sample 1O2 may be generated through Förster-type energy transfer from excited sub-surface Ti3+ centers.

The shortage of tissues and organs for transplantation is an urgent clinical concern. In situ 3D printing is an advanced 3D printing technique aimed at printing the new tissue or organ directly in the patient. The ink for this process is central to the outcomes, and must meet specific requirements such as rapid gelation, shape integrity, stability over time, and adhesion to surrounding healthy tissues. Among natural materials, silk fibroin exhibits fascinating properties that have made it widely studied in tissue engineering and regenerative medicine. However, further improvements in silk fibroin inks are needed to match the requirements for in situ 3D printing. In the present study, silk fibroin-based inks were developed for in situ applications by exploiting covalent crosslinking process consisting of a pre-photo-crosslinking prior to printing and in situ enzymatic crosslinking. Two different silk fibroin molecular weights were characterized and the synergistic effect of the covalent bonds with shear forces enhanced the shift in silk secondary structure toward β-sheets, thus, rapid stabilization. These hydrogels exhibited good mechanical properties, stability over time, and resistance to enzymatic degradation over 14 days, with no significant changes over time in their secondary structure and swelling behavior. Additionally, adhesion to tissues in vitro was demonstrated.

The present study reports on the development of a new binary filler system for rubber composites, SiO2@Al2O3, where Al2O3 sheets are grown onto SiO2 nanoparticles aggregates by a sustainable water-based soft-chemistry approach. The aim is to synergistically integrate the intrinsic thermal conductivity properties of Al2O3 with the peculiar reinforcement ability of SiO2 in an easy one-pot solution, which has been exploited to prepare polybutadiene (PB) model composites by a simple solvent casting technique. More in detail, the binary filler was used as-prepared or suitably surface functionalized with 3-(Trimethoxysilyl)propylmethacrylate (TMSPM). The filler compatibilization and interplay with the polymeric matrix have been inspected by solid state NMR in conjunction with scanning electron microscopy. These investigations highlighted that the presence of alumina in the binary filler does not undermine the capability of silica in generating polymer chains stiffening and indicated a significant effect of the silanization in providing better filler networking and interaction with the PB host ensuring, in principle, an enhanced thermal transport. Accordingly, thermal conductivity measurements revealed that SiO2@Al2O3 introduction in PB induces a remarkable upgrade of the heat transfer, which becomes much more relevant upon surface modification with TMSPM. These results appear encouraging, paving the possibility of applying SiO2@Al2O3 model system to more complex case studies, where both improved thermal conductivity and enhanced reinforcement are required, such as tires tread formulations.

Sepiolite clay is a natural filler particularly suitable to be used with polysaccharide matrices (e.g., in starch-based bio-nanocomposites), increasing their attractiveness for a wide range of applications, such as packaging. Herein, the effect of the processing (i.e., starch gelatinization, addition of glycerol as plasticizer, casting to obtain films) and of the sepiolite filler amount on the microstructure of starch-based nanocomposites was investigated by SS-NMR (solid-state nuclear magnetic resonance), XRD (X-ray diffraction) and FTIR (Fourier-transform infrared) spectroscopy. Morphology, transparency and thermal stability were then assessed by SEM (scanning electron microscope), TGA (thermogravimetric analysis) and UV–visible spectroscopy. It was demonstrated that the processing method allowed to disrupt the rigid lattice structure of semicrystalline starch and thus obtain amorphous flexible films, with high transparency and good thermal resistance. Moreover, the microstructure of the bio-nanocomposites was found to intrinsically depend on complex interactions among sepiolite, glycerol and starch chains, which are also supposed to affect the final properties of the starch–sepiolite composite materials.