This study investigates colorimetric behaviour of sustainable coatings fabricated using cellulose nanocrystals (CNCs) as a biopolymeric binder and different types of pearl luster pigments, which differ in chemical composition, pigment color, and particle size. Coatings that combine high-performance CNCs with pearl luster pigments, which impart angle-dependent color (iridescence) due to their optically thin layers, offer a unique optical effect driven by the interplay of structural color and pigment-based reflection. The black paper was double coated in machine direction using K Control Coater. Colorimetric values (CIELAB) and spectral reflectance (R%) of the coating were measured across the visible spectrum from 400 to 700 nm, with a fixed illumination angle of 45° and viewing angles of -15°, 15°, 25°, 45°, 75°, and 110°. Results reveal pronounced shifts in reflectance intensity and CIELAB values with changing viewing angle, driven by the type of pearl luster pigments and their orientation. The findings provide insight into the design of sustainable, visually dynamic coatings for decorative and functional applications, where controlled angular color variation is desirable.

Epoxy-amine coatings are widely used for metal protection because they provide strong interfacial bonding, long service life, and excellent corrosion resistance. In this work, Bisphenol A diglycidyl ether (DGEBA) cured with m-xylylenediamine (m-XDA) was used as a model system to investigate how environmental CO₂ affects coating heterogeneity and optical appearance. Particular attention was given to amine blushing, since m-XDA can react rapidly with atmospheric CO₂ to adsorb and to form carbamated species on the coating surface, leading to reduced transparency of both the bulk polymer and the film.

DGEBA/m-XDA specimens were cured at room temperature under either N₂ or a CO₂-containing ambient atmosphere, and characterised using Fourier-transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). The CO₂-exposed samples showed pronounced inhomogeneity throughout the bulk, obvious surface amine blushing, and strong bands at 2400–2300 cm⁻¹ attributed to CO₂ species trapped in the polymer matrix, which correlated with decreased transparency, whereas the N₂-cured samples appeared more homogeneous and showed no evidence of CO₂ capture. Subsequent high-temperature treatment at 160 °C greatly reduced the CO₂-related FTIR bands, indicating that CO₂ near the surface could desorb, although cloudiness remained in much of the bulk and only localised regions showed disappearance of carbamate/carbamic acid features with concurrent strengthening of bands near 1700 cm⁻¹ and in C–N/N–H regions.

Free-standing films cured at 60 °C and post-cured at 100 and 160 °C were also evaluated by EIS, which revealed no significant differences in coating resistivity between CO₂-exposed and N₂-cured samples. These results suggest that CO₂ uptake and carbamate formation at the surface mainly influence visual appearance and micro-scale heterogeneity rather than global barrier performance. The study highlights the critical role of cure atmosphere in controlling amine blushing and optical properties of epoxy-amine coatings without severely compromising their electrochemical corrosion protection.

Ηard chromium (HC) has been the dominant protective coating for a wide range of applications offering high hardness (750-1050 HV), and excellent wear and corrosion resistance However, the hard chrome plating process involves the use of hexavalent chromium, (Cr(VI)), which is highly toxic, carcinogenic and mutagenic and associated with severe respiratory problems. Thus the emission and wastes of the process are dangerous for the workers and the environment. Consequently, on February 15^th 2019, REACH Committee has set a stricter regulation frame for the use of Cr(VI) substances, proposing authorization and limits to the use of chromium trioxide[1]. To address this challenges, the replacement of HC coatings with novel nickel-based nanocomposite coatings is investigated. The European research project MOZART promotes the incorporation of silicon carbide and graphene nanoparticles (NPs) in the Nickel matrix leading to two novel coatings with enhanced physicochemical, mechanical and environmental properties are examined in the framework of the. In this study, a sustainability assessment of two coatings is performed, comprising Life Cycle Assessment and Life Cycle Cost analyses according to the ISO 14040-44 standards with a functional unit of 1m² of coated surface, with 10um coating thickness. The results demonstrate significant improvement of human carcinogenic toxicity and freshwater ecotoxicity reduction while the economic performance proving the feasibility of the new coatings.

[1] REACH: Commission imposes strict conditions over the use of hazardous chemicals used in automotive, aerospace and medical sectors - Internal Market, Industry, Entrepreneurship and SMEs. Retrieved December 5, 2025, from https://single-market-economy.ec.europa.eu/news/reach-commission-imposes-strict-conditions-over-use-hazardous-chemicals-used-automotive-aerospace-2019-02-15_en

Developing sustainable alternatives to Cr(VI)-based metallization requires a mechanistic under-standing of adhesion, surface activation, and metal deposition across different length and time scales. Within the FreeMe project, we have es-tablished a unified multiscale modelling frame-work that links atomistic reactivity, interfacial behaviour, and mesoscale metal deposition phe-nomena relevant to Cr(VI)- and Pd-free Plating on Plastics (PoP).

Adhesion between polymer substrates and epoxy resins was characterised through classical Molec-ular Dynamics simulations. The methodology was first applied to PLA–epoxy systems and sub-sequently extended to ABS with different epoxy formulations, enabling the prediction of interfa-cial energies, resin penetration and structural or-ganization in relation to adhesion performance.

The chemical etching stage was analysed through complementary quantum and reactive simula-tions. Density Functional Theory calculations re-solved complete oxidation pathways for the ABS monomers, identifying feasible mechanisms and activation barriers for piranha-based etching. Re-active Molecular Dynamics (ReaxFF) simula-tions reproduced the dynamic interaction be-tween oxidants and the polymer surface, reveal-ing composition- and energy-dependent diffu-sion regimes, penetration depths and the evolu-tion of functional groups. Kinetic Monte Carlo simulations were used to extrapolate the oxida-tion patterns to longer times, predicting the tem-poral increase in surface energy associated with activation.

Finally, the deposition of nickel on etched ABS was investigated using a coarse-grained model, which captures mesoscale interactions between Ni species and the polymer surface. The model predicts Ni coverage as a function of temperature and pressure and identifies the dominant bead-level interactions governing deposition

This framework provides a predictive, SSbD-aligned toolset to support the design and optimi-sation of sustainable metallization processes for polymer substrates.

Dust accumulation or stains on photovoltaic (PV) panels pose a significant challenge, reducing efficiency and shortening lifespan. Commonly used cleaning methods, such as manual cleaning, rely on water, which raises concerns about the economic and environmental feasibility of the technique. To address this challenge, a self-cleaning mechanism via a novel water/isopropyl alcohol-based coating developed by NanoPhos S.A. is investigated, which provides antireflective performance that could increase the transmittance of PV glass while reducing dust deposition. In this study, the impact of a self-cleaning, super-hydrophilic, and photocatalytic coating is investigated. The evaluation of the coated panels is demonstrated in accordance with IEC 61724-1:2021 in Greece, at the Technological and Cultural Park demonstration site in Lavrion. To evaluate the PV performance, crucial parameters, such as yields, losses, and efficiencies, are computed. The analysis is conducted within the services offered by the Open Innovation Test Beds, which enable material suppliers to integrate their innovative, carbon-neutral material solutions into the European Key Value Chain. The study's findings indicate an average gain of over 5% in the performance ratio across the entire period.

Thin-film hydrophilic polymer coatings represent an effective platform for the development of optical humidity sensors based on color changes. Hydrophilic polymers absorb water molecules from the environment, which leads to spontaneous swelling and a proportional increase in the thickness of the film. When film is deposited on reflective substrate even small changes (a few nanometers) in thickness are sufficient to shift the reflectance spectrum and cause a distinct change in the perceived color. This allows visual and contactless detection of humidity with high sensitivity, the process being fully reversible upon drying. Combined with the ease of fabrication, low cost, and the possibility of chemical tuning, thin-film hydrophilic polymers represent a promising material for integration into next-generation humidity optical sensor platforms.

A new hygrosensitive poly(vinyl alcohol) derivatives comprising grafted poly(N,N-dimethylacrylamide) chains of varied length and graft density were developed recently and has been shown to be a promising materials for humidity detection. The influence of the grafting density and chain length on the sensing properties for two copolymers annealed at three different temperatures (60◦C, 120◦C and 180◦C) was systematically studied. Polymer films deposited by spin-coating method with a thickness of 140-200 nm were investigated spectrophotometrically and the optical constants (refractive index and extinction coefficient) were determined. When exposed to humidity in the range of 5-95% RH the films demonstrated a relative change in thickness between 50% and 100%, as well as a change in the refractive index. It has been shown that hysteresis is influenced by both - the annealing temperature and the structure of the copolymer. The moisture absorbed in the films at 95% RH humidity was evaluated by using the quartz microbalance method. Both structural variations and annealing temperature were found to have an impact on copolymers’ optical and sensing properties.

Acknowledgements: The authors acknowledge the financial support from the Bulgarian National Science Fund under the Grant No. KP-06-COST/4 under COST Action CA21121 “European Network for the Mechanics of Matter at the Nano-Scale” (MecaNano). Research equipment of Distributed Research Infrastructure INFRAMAT, part of Bulgarian National Roadmap for Research Infrastructures, supported by Bulgarian Ministry of Education and Science was used in this investigation.

Carbon-based materials play an important role in today's science and technology. Carbon is a very versatile element whose two most interesting allotropic forms are Diamond (sp3) and Graphite (sp2). This way, the DLC has consolidated all its applications in the automotive and mechanical sectors in general. The management of the sp3/sp2 ratio yields various types of DLC that enhance hardness, reduce friction, and improve the corrosion resistance of the steel component.

The demand for DLC coating on steel components for endothermic and hybrid engines (pins, valves, camshafts, gears) is constantly growing; DLC improves engine performance and reduces emissions into the atmosphere.

In this presentation, the DLC deposited using the hybrid PVD-PaCVD (Physical Vapor Deposition-Plasma-assisted Chemical Vapor Deposition) technology will be examined. The modification of the layers, their thicknesses, compositions, and the containment of surface defects enhance the layer's hardness, reduce friction, and increase its resistance to corrosion. These characteristics can therefore be measured using laboratory instruments such as a nanoindenter, a contact tribometer, and a salt spray chamber. The next step is the bench test to assess results closer to real conditions. After laboratory analysis and bench tests, the applications are presented in 3 case histories: the increase in abrasion resistance in injection pins, the reduction in the friction coefficient on rocker arms, and the improvement in corrosion resistance in bipolar plates.

Diamond-Like Carbon (DLC) films are employed to improve the sliding wear performance of tribosystems, including those used in the automotive and aerospace sectors. Recently, Al- and Ti- based additively manufactured materials have gained increasing interest in these sectors due to their high strength/density ratios. However, their relatively low hardness affects their wear resistance unless coatings are applied. DLC-based films offer a potential solution, but the softness of these substrates could represent an issue. Indeed, when the substrate is more elastically and plastically compliant than the film, the latter could experience excessive deformation, leading to failure.
In this work, we studied the effect of substrate hardness on the adhesion and wear behaviour of PVD and PA-CVD DLC-based coatings deposited onto AlSi10Mg and AlSi7Mg alloys produced via Laser Powder Bed Fusion (L-PBF) and subjected to different heat treatments. The unique microstructure of L-PBF materials indeed allows non-conventional heat treatments that result in a wide range of achievable properties. Specifically, we considered substrates in four different conditions: as-built, directly aged, solution-treated, and T6 (solutionized and aged). As the hardness of the substrate decreased due to increasing reorganization and coarsening of the fine cellular network of eutectic Si, the fraction of delaminated coating area in the Rockwell indentation test increased, and the delamination load in the scratch test decreased. In the ball-on-disc test, the DLC top layer followed the plastic deformation experienced by all substrates under the contact stress. In contrast, the WC/C intermediate layer cracked and caused localized film spallation, with greater severity on softer substrates. The additional stress concentration caused by the random presence of open surface pores on L-PBF substrates promoted larger spallation or delamination whenever the wear trace passed through one of them. After the T6 treatment, the extensive reduction in hardness led to systematic coating delamination.

Recent advances in materials science have accelerated the development of high-entropy alloys (HEAs), a class of multicomponent materials recognized for their enhanced properties, structural stability, high-temperature resistance, and oxidation tolerance, enabling applications, such as aviation turbine engine hot-section components and other high-temperature environments. To ensure that innovations align with safety, sustainability and socio-economic targets, the European Union’s (EU) Safe-and-Sustainable-by-Design (SSbD) framework provides a methodology for evaluating chemicals, materials, and products early in their design and throughout their entire life cycle. The methodology consists of five hierarchical steps, applied in an iterative way, aiming for continuous improvement across EU target pillars.

The EU-funded M2DESCO project aims to develop HEA-based coatings deposited via Physical Vapor Deposition (PVD), free from hazardous substances and with reduced reliance on critical raw materials for industrial tooling applications (e.g., hot-stamping tools). Central to this effort is the implementation of the SSbD framework to support a comprehensive evaluation of safety and sustainability aspects of the developed coatings. In the present work, a scoping analysis is performed to establish the objectives of the evaluation, including system boundaries, (re-)design actions, and relevant indicators that will guide the SSbD assessment. A simplified SSbD assessment follows, reflecting the project’s current maturity level across the coatings’ developed life-cycle stages. The current focus on safety assessment includes hazard classification for the metallic elements that comprise the HEA coatings, occupational exposure during the manufacturing of the HEA targets and the PVD coating process, as well as exposure during the use-phase of the coated hot-stamping tools. Results will focus on materials’ toxicity evaluation based on current OECD guidelines and relevant ISO standards and quantitative exposure assessment for the production and the application phase evaluating human and environmental safety aspects via the use of in silico tools and established databases, such as European Chemicals Agency (ECHA). Sustainability evaluation follows through Life Cycle Assessment, presenting preliminary identifications of potential environmental hotspots in the early design phase. The goal of the present work is to showcase the progress made in the implementation of the SSbD framework for the production of novel HEA coatings, while highlighting methodological limitations that need to be addressed to strengthen the integration of safety and sustainability principles within the broader materials industry.

Hydrogen energy is one of the important candidates in the search for an alternative energy source to fossil fuels due to their environmental hazards. The fact that hydrogen, which is colorless and odorless, has flammable and explosive properties at concentrations above 4% makes hydrogen safety an important issue [1]. Therefore, sensors that can accurately detect low concentrations of hydrogen at low temperatures are needed for hydrogen safety. This will ensure the safe use of hydrogen in the production, transportation, storage, and technological and industrial applications [2]. Titanium dioxide (TiO₂), has attracted attention in many technological applications due to its advantages in structural properties. TiO₂ nanotube production has been evaluated in gas sensor research due to the convenience it provides in the surface area [3].

One of the methods used for the production of TiO2 nanotubes is the anodization method [4]. Unlike previous studies, the dual anodization method was preferred in this study. In order to prepare the electrolyte containing 0.5% NH₄F, 47.25 mL of ethylene glycol, 2.50 mL of ultrapure water, and 0.25 g of NH₄F were added to the mixture as a result of the stock solution calculation for a 50 g sample. Platinum (Pt) and titanium (Ti), used as cathodes, were immersed in the electrolyte. The first anodization step was applied at 20 °C, 60 V, for 2 hours, and the formation of TiO2 nanotubes was observed. The second anodization step was applied at 20 °C, 40 V, for 1 hour. Thanks to the two-stage anodization protocol, nanotubes with morphological integrity, high regularity, and homogeneous wall thickness were produced. SEM images and XRD analysis were performed on the produced nannotubes.

Following the anodization process, electrical characterization and gas tests were performed on the completed Ti/TiO2 nanotubes/Pt device. The results showed that the nanotubes produced by dual anodization had better performance.

This study was funded by The Scientific and Technological Research Council of Türkiye (TUBİTAK), Project Number: 123F411.