Introduction
The shift from a linear to a circular economy is essential for reducing global resource consumption, minimizing waste, and promoting sustainable materials. This transition supports the development of bio-based thermoset polymers, the upcycling of industrial waste-derived fillers, and the use of environmentally friendly manufacturing technologies. Vat photopolymerization (VPP) has emerged as a highly versatile method with great potential. As a light-driven process, it enables high-resolution printing and the fabrication of complex geometries.

Materials and Methods
The resin formulation consisted of acrylate epoxidized soybean oil (AESO) and isobornyl methacrylate (IBOMA) in a 1:1 weight ratio, with 2 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) as a radical photoinitiator. Bamboo filler was added at 3, 5, and 10 phr to produce bio-based composites. Both neat and filled formulations were processed using a Phrozen Sonic Mini 8K LCD printer equipped with a 50 W linear projection LED module operating at a UV wavelength of 405 nm.

Results and Discussion
The addition of bamboo enhanced the mechanical and viscoelastic properties. The Young’s modulus increased from 1189 MPa (A-IB) to 1397 MPa (A-IB+B10), corresponding to an enhancement of approximately 17%. The storage modulus (E’) improved from 1140 MPa to 3324 MPa. The glass transition temperature shifted from 92°C to 95°C. Thermogravimetric analysis confirmed that thermal stability was not negatively affected. Although bamboo increased viscosity, it remained within the optimal range for VPP, ensuring processability.

Conclusions
This study demonstrates that bio-based photocurable formulations can be efficiently used in VPP to produce high-performance composites. Bamboo filler provides sustainable reinforcement, improving mechanical and viscoelastic performance without compromising printability or thermal stability. These findings highlight the potential of combining bio-based resins with natural fillers to develop sustainable, high-performance materials for AM applications, contributing to the broader goals of the circular economy and green manufacturing.

Plastics have become indispensable in modern life, valued for their versatility, affordability, and ease of manufacture. As their use expands across industries such as automotive, aerospace, consumer electronics, and construction, understanding their mechanical performance under various loading conditions becomes increasingly important. Despite their advantages, polymers are susceptible to damage and degradation over time, especially when subjected to sustained or repeated mechanical stresses. This study examines recent developments in fracture mechanics as applied to polymeric materials, with a focus on the need for precise design and sizing to ensure structural reliability in practical applications. A comprehensive understanding of how polymers respond to different mechanical loads, particularly in the presence of microstructural defects or environmental influences, is essential for predicting long-term performance and preventing premature failure. The research specifically investigates the mechanical behavior of ABS (Acrylonitrile Butadiene Styrene) under uniaxial tensile loading, emphasizing the role of damage accumulation in altering its mechanical properties.

To achieve this, the study employs experimental testing combined with advanced analytical techniques, including non-linear regression and damage modeling. These methods enable the identification of critical failure thresholds, providing valuable insights for maintenance planning, design optimization, and the development of more durable polymer-based components in engineering systems. Moreover, the results lay the groundwork for extending damage prediction models to other thermoplastic materials under similar loading conditions

Introduction: The increasing demand for biocompatible and flexible electronic materials has stimulated the research into conductive hydrogels, particularly for biosensors and wearable device applications. Gelatin methacryloyl (GelMA), derived from cold-water fish skin, offers a renewable and biocompatible matrix. This study investigates the synthesis and characterization of GelMA hydrogels loaded with silver nanoparticles (AgNPs) to achieve conductivity, exploring the impact of formulation and environmental factors on material properties.

Methods: GelMA was synthesized and crosslinked using a visible light-activated photoinitiator (BAPO-PEG). AgNPs were incorporated via in situ reduction during crosslinking and by post-crosslinking immersion in silver nitrate solutions. Hydrogel properties were assessed using Fourier-transform infrared spectroscopy (FTIR), photorheology, thermogravimetric analysis (TGA), swelling tests, and electrical conductivity measurements under varying humidity conditions. Piezoresistive behavior was evaluated by measuring current changes under applied compressive strain.

Results: FTIR confirmed successful GelMA synthesis. Photorheology optimized BAPO-PEG concentration for rapid curing. TGA demonstrated thermal stability up to 260-270°C. High water absorption (300%) was observed. In situ AgNP formation delayed gelation, favoring immersion for AgNP incorporation. Electrical conductivity was highly dependent on humidity, with dried samples exhibiting insulating behavior. Conductivity significantly increased with hydration, reaching 6.84 S/m for samples with the highest silver content (GelMA/Ag-50) at 100% relative humidity. Compressive strain enhanced conductivity, indicating piezoresistive properties suitable for sensing applications.

Conclusion: This study demonstrates the successful synthesis of conductive bio-based hydrogels by incorporating AgNPs into a GelMA matrix derived from fish skin gelatin. The resulting materials exhibit tunable electrical properties responsive to humidity and mechanical strain, making them promising candidates for biosensors, humidity sensors, and flexible electronic devices. Further research will focus on optimizing AgNP dispersion and long-term stability for real-world application.

Abstract: Polyurethane (PU) materials are extensively employed in construction, automotive, footwear, and packaging industries due to their durability and versatile properties. However, their crosslinked thermoset structure presents significant challenges for end-of-life disposal, contributing to persistent environmental accumulation and long-term waste management issues. In recent years, chemical recycling methods,particularly glycolysis, have gained attention as promising approaches for PU waste valorization.

Glycolysis involves the cleavage of urethane linkages using a glycol (e.g., ethylene glycol) in the presence of catalysts such as organometallic compounds. This process leads to the formation of low-molecular-weight polyols, which can be reused in repolymerization or formulation of new materials. Optimization of parameters, such as temperature, catalyst concentration, and glycol-to-PU ratio, significantly influences degradation efficiency and product quality.

Analytical techniques like FTIR, NMR, and GPC are commonly used to characterize the glycolyzed products. FTIR spectra typically show the disappearance of urethane peaks and emergence of hydroxyl functionalities, indicating successful depolymerization. NMR provides detailed insight into the structure of the recovered polyols, while GPC confirms molecular weight reduction and homogeneity. During the reaction, controlled volatilization of excess reagents or by-products may occur, which can be minimized or recovered under reduced pressure conditions.

This review highlights recent developments in the glycolytic recycling of PU waste, emphasizing environmentally benign protocols aligned with green chemistry principles. The process not only reduces dependency on fossil-based raw materials but also enables a circular economy approach to polymer sustainability. Continued research is essential to scale up these methods and integrate them into industrial waste management systems.

Two types of shape-stabilized composite Phase Change Materials (sscPCMs)—PEG₁₀₀₀/silica/MWCNTs and PEG₆₀₀₀/silica/MWCNTs, respectively—were embedded in two different inorganic matrices that are commercially available as building materials (lime-cement mortar and gypsum) in order to obtain building elements with latent heat storage properties. The two PEG/silica/MWCNTs materials were prepared in our lab using a previously published method [1]. Three different concentrations of the two sscPCMs (2.5%, 5%, and 10%) were added to the mortar, whereas only a 10% concentration of sscPCMs was investigated for gypsum. The new PEG–mortar and PEG–gypsum composites were cast in parallelepiped molds (L x w x h = 50 mm x 30 mm x 20 mm) to obtain brick-type construction elements (for building facades). The bricks thus produced were characterized from a morpho-structural point of view and were subjected to tests regarding their compressive strength. In order to verify their functionality, the behavior of the materials after exposure to 62 repeated heating–cooling cycles was also evaluated.

Funding: This work was supported by Romanian Ministry of Education and Research through INCDCP ICECHIM Bucharest 2022-2027 Core Program PN. 23.06 – ChemNewDeal, by project no. PN. 23.06. 01.01 - AQUAMAT.

References:

1. C.L. Nistor, I.C. Gîfu, E.M. Anghel, R. Ianchis, C.-D. Cirstea, C.A. Nicolae, A.R. Gabor, I. Atkinson, C. Petcu, Novel PEG6000–Silica-MWCNTs Shape-Stabilized Composite Phase-Change Materials (ssCPCMs) for Thermal-Energy Storage, Polymers 2023, 15(14), 3022; https://doi.org/10.3390/polym15143022

Water pollution remains a critical global environmental challenge. According to UNESCO, approximately 80% of wastewater is discharged without adequate treatment, while nearly half the world’s population resides in water-stressed regions. Photocatalysis has emerged as a promising green technology for combating water pollution due to its efficiency, cost-effectiveness, and environmental compatibility. In particular, photocatalytic degradation of organic pollutants, such as dyes, has garnered significant attention.

Our research focuses on the development of novel, sustainable cellulose-supported photocatalysts designed for efficient sunlight-driven degradation of organic contaminants. Cellulose, with its high surface area, reactive functional groups, and compatibility with metal oxides, serves as an effective support material. Additionally, its capacity to mediate electron transfer contributes to reduced charge recombination and enhanced photocatalytic activity. We engineered a range of cellulose-based platforms for the immobilization of metal oxide nanoparticles (CeO₂, ZnO), to create hybrid nanocomposites with improved photocatalytic performance under both UV and visible light. These materials demonstrated effective degradation of a range of hazardous dyes (methyl orange, Congo red, rhodamine B, methylene blue), alongside excellent reusability and operational stability.

Currently, we are designing aerogel-based macroporous matrices as advanced supports for photocatalyst immobilization. These structures aim to increase catalyst loading, improve mass transfer, and prevent leaching. Unlike dense films or submerged polymeric composites, our approach employs floatable substrates positioned at the air–water interface. This configuration maximizes solar light exposure, enhances oxygen availability for radical generation, and significantly boosts overall photocatalytic efficiency.

Our work contributes to the advancement of sustainable water treatment technologies and highlights the potential of biopolymer-based photocatalytic systems for practical environmental remediation applications.

Acknowledgments

This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS -UEFISCDI, project number PN-IV-P1-PCE-2023-1020, within PNCDI IV.

With the help of experimental testing and finite element analysis (FEA), this study conducts an in-depth investigation into the mechanical action of thermoplastic polyurethane (TPU) and polylactic acid (PLA) that have been created using 3D printing technology. In order to characterize their behavior under a variety of infill densities and patterns, tests of uniaxial tensile and cyclic compression were carried out. PLA revealed stronger stiffness and yield strength, making it excellent for rigid prototypes, but TPU demonstrated superior elasticity and energy dissipation, making it suited for flexible applications. Furthermore, TPU was shown to be suitable for flexible applications.
For the purpose of developing predictive models for the mechanical qualities, the research combined statistical analysis through the use of Response Surface Methodology (RSM). This made it possible to optimize the printing parameters. The capacity of finite element analysis (FEA) simulations to accurately replicate experimental results by utilizing proper hyperelastic models is evidence that these simulations are capable of capturing the complicated material response. The purpose of this effort is to build a reliable system for evaluating and improving the mechanical performance of 3D-printed materials. This methodology will provide useful insights for the design of these materials and their application in a variety of engineering branches.

The development of targeted anti-cancer therapies is a critical area of research, aiming to overcome the limitations of conventional treatments that often cause severe side effects and damage to healthy cells. In this study, we report the synthesis and characterization of a novel, smart nanoparticle-based drug delivery system designed for enhanced cancer cell targeting. Specifically, niosomes were surface-functionalized with a dual-modified chitosan (CS) incorporating folic acid (FA) and hyaluronic acid (HA), targeting receptors that are commonly overexpressed on cancer cells. Importantly, the modification preserved free amino groups on the CS backbone, enabling pH responsiveness in acidic environments such as the tumor microenvironment. This design confers the system with triple targeting capabilities: receptor-mediated (FA and HA) and pH-sensitive (CS) targeting. Two bioactive compounds were co-encapsulated within the niosomes: hydrophobic curcumin, known for its anti-cancer properties, and hydrophilic ascorbic acid (10 mg/mL), offering potential synergistic therapeutic effects. FTIR analysis confirmed the successful dual modification of CS with FA and HA, its effective coating onto the niosomes, and the presence of unmodified amino groups. Dynamic light scattering (DLS) analysis demonstrated optimal formulation with cholesterol and surfactants (Span 60 and Tween 60 at a 0.2:1:1 ratio), producing unloaded niosomes of 101 nm in diameter. Surface coating with modified CS increased the particle size to 174.5 nm, with further size increase upon drug encapsulation. Scanning electron microscopy (SEM) revealed a morphology suitable for cellular uptake, while in vitro cytotoxicity studies confirmed enhanced efficacy against cancer cells. The proposed multifunctional niosomal system exhibits promising features for targeted anticancer therapy, combining receptor-specificity, pH responsiveness, and synergistic drug action for improved therapeutic outcomes.

The main objective of using natural fibers as reinforcement phase in composites is to improve the mechanical properties and production of lightweight materials. Moreover, their biodegradability, renewability, nontoxicity, and abundance in nature make natural fibers ideal for use in composites. The valorization of biomass is one of the important ways we can control the consumption of non-renewable resources. Also, biocomposites have gained considerable academic and industrial attention due to their improved properties (thermal, mechanical and barrier, as well as fire resistance) compared to virgin polymer. Properties improved in the presence of fillers include an increase in Young's modulus, yield strength, a decrease in gas permeability, an increase in thermal resistance and an increase in biodegradability rates. Integrating cellulose fibers into PLA enables the development of advanced composites that exhibit notable improvements in mechanical strength, thermal stability, barrier performance, and overall sustainability.

The present work consists of extracting cellulose fibers from gauze strips (F-BG) for the production of PLA/F-BG biocomposites. The improvement of PLA and cellulose fibers' compatibility was achieved by adding a synthesized compatibilizer (PLA-g-MA). The fiber loading in PLA/F-BG composites varied between 1% and 3%. Rheological analysis indicated that the incorporation of F-BG fibers led to a reduction in the melt flow index, with a more pronounced decrease observed as the PLA-g-AM content increased. Moreover, mechanical characterization through impact and flexural tests showed that impact resistance decreased with higher F-BG content. However, F-BG addition significantly enhanced the flexural strength and elastic modulus of the composites.

The main task of modern biomedical engineering is to prevent and control infections during the healing of skin wounds. Conventional antibacterial therapies frequently prove ineffective due to the emergence of antibiotic-resistant bacterial strains and their ability to form biofilms. Consequently, the development of antibacterial non-woven wound dressings that promote tissue regeneration, combat infections, and combine biocompatibility, mechanical strength, and potential for bioactive functionalization is regarded as a promising direction.

The aim of this study is to evaluate the antibacterial activity of coaxial nonwoven materials based on polycaprolactone (PCL) and collagen (Col), modified with varying concentrations of aloe vera (AV) extract and copper oxide (CuO) nanoparticles (NPs). The materials, with an average fiber diameter of 110–120 nm, were fabricated using electrospinning. The successful incorporation of AV extract and CuO NPs was confirmed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and contact angle measurements. The antibacterial activity of the resulting materials was assessed by the colony-forming unit counting method. The tested strains included both Gram-positive and Gram-negative bacteria, as well as Candida species.

The resulting coaxial PCL/Col-based materials modified with CuO NPs and AV extract exhibited strong antibacterial properties. The most effective formulation, containing 2 wt.% CuO NPs, achieved complete inhibition of eight Gram-negative, five Gram-positive bacterial, and three fungal strains within the first 6 hours of incubation. Materials containing 15% AV extract also showed significant antibacterial activity within 24 hours against strains including E. coli ATCC25922, E. coli S176, E. coli ATCC35218, P. aeruginosa S246, S. aureus ATCC29213, and S. aureus ATCC700699. The combined use of CuO NPs and AV extract represents a promising strategy for developing biocompatible materials with prolonged antibacterial activity.

This work was performed with the support of the Russian Science Foundation (agreement № 24-79-10121).