This study explores degradation behaviours and mechanical performance of 3D-printed recycled polycarbonate (rPC) over multiple recycling cycles using fused granulate fabrication (FGF), a sustainable and scalable 3D printing technique. rPC flakes were subjected to ten recycling cycles, and their thermal, chemical, and mechanical properties were characterised using DSC, TGA, FTIR, and mechanical testing. The results reveal that thermal stability gradually decreases with repeated processing: the glass transition temperature dropped from 110.2 °C to 96.4 °C after ten cycles, while the degradation onset temperature reduced slightly, indicating progressive thermal degradation. FTIR analysis showed transient structural improvements in early cycles, followed by loss of key functional groups due to chain scission and oxidative degradation. Mechanical testing demonstrated a temporary enhancement in tensile strength and flexural strength—peaking at 68.59 MPa and 76.4 MPa respectively—linked to improved chain alignment. However, these gains were reversed after the fifth cycle, with significant declines in strength, modulus, and impact strength. Fractography confirmed a transition from ductile to brittle failure beyond five cycles. FGF printing also reduced manufacturing time by up to 84% compared to fused filament fabrication, emphasising its viability for circular manufacturing. The findings offer critical insights into the recyclability feasibility of engineering polymers and support broader application of FGF in polymer sustainability.

Given the growing accumulation of waste from agricultural, domestic, and industrial activities, and the continued dependence on fossil-based plastics, a sustainable alternative based on the bacterial biotransformation of waste for the production of polyhydroxyalkanoate (PHA) bioplastics is proposed. This research focuses on evaluating agro-industrial waste generated in Santander, Colombia, as a raw material for the production of PHAs, within a circular economy framework that aims to repurpose waste and give it a second useful life. A methodology was designed based on the fermentation of two native bacterial strains, Bacillus thuringiensis and Bacillus cereus, using waste such as pineapple peels and copoazú pulp. The process consisted of two stages. In the first stage, PHA production by each strain was evaluated using the waste products, with concentrations based on their reducing sugar content (10 g/L). In the second stage, fermentation parameters such as time, agitation, waste concentration, inoculum concentration, and pH, were optimized using the waste–strain combination that showed the highest yield in the initial evaluation. The preliminary results show that the highest yield of polyhydroxybutyrate (PHB), the predominant PHA produced, was obtained using pineapple peels and Bacillus thuringiensis, with an accumulation of 71.8 ± 4.5%. Meanwhile, Bacillus cereus showed a biopolymer accumulation of 68.19 ± 14.02%. This demonstrates the potential of pineapple peels as a carbon source for the production of biopolymers, highlighting their viability as an economic and environmental alternative to synthetic plastics. In addition, it contributes to the recovery of agro-industrial waste and the reduction in the environmental impact associated with its poor management.

Introduction: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable bioplastic offering sustainable alternatives to petroleum-based plastics. However, its brittleness and poor processability limit packaging applications. This study enhances PHBV performance by incorporating food waste-derived additives: coffee oil epoxide (COE) as plasticizer and eggshell-derived calcium carbonate (CaCO₃) as reinforcing filler with high-molecular-weight natural rubber (NR). The objective is to improve the thermal, mechanical, and barrier properties of PHBV while maintaining its biodegradability for environmentally friendly packaging applications.

Method: PHBV blends were prepared using twin-screw extruder with varying NR, COE, and CaCO₃ compositions. Films were characterized using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), mechanical tensile testing, and oxygen transmission rate (OTR) analysis. Soil burial biodegradation testing over 117 days assessed environmental impact through weight loss and thickness reduction. Statistical analysis used one-way ANOVA with Tukey's HSD test (p < 0.05).

Results: COE addition improved PHBV/NR flexibility and processability, while CaCO₃ enhanced mechanical strength. SEM showed uniform dispersion without phase separation. DSC results indicated significant melting point decrease from 170.4°C (PHBV) to 166.5°C (PHBV/NR/COE/CaCO₃), and crystallinity reduction from 68.5% to 50.8% with COE and eggshells incorporation, confirming improved flexibility and reduced brittleness. OTR values decreased significantly for COE-containing sheets, indicating enhanced barrier properties. The biodegradation study revealed weight loss of 26.25% for PHBV and 28.85% for PHBV/NR/COE sheets, confirming environmental compatibility. Processing trials indicated that PHBV/NR/COE blends formed well-defined sheets, unlike PHBV/NR blends, which were sticky and difficult to process.

Conclusion: Blending PHBV with waste-derived COE and CaCO₃ plus NR significantly enhanced thermal stability, mechanical strength, and barrier properties without compromising biodegradability. These modified films demonstrate improved flexibility, processability, and environmental performance, making them strong candidates for sustainable food packaging. This study highlights upcycled food waste potential in advancing green polymer solutions and supports industrial scalability.

The synthesis and characterization of a series of carbazole-based polymers are investigated, focusing on their potential application in AI-driven bistable memory devices and neuromorphic computing architectures. These polymers incorporate carbazole moieties into their sidechains, facilitating π–π interactions and enhancing charge transport. When deposited as thin films between ITO and Al or Au electrodes, these materials demonstrate clear memristive behavior through voltage-induced conductance switching. The devices exhibit bistable conductivity with a pronounced hysteresis, retaining ON/OFF states for extended periods—several hours—when subjected to electric fields above a certain threshold, as detailed in recent reports [1–3].

In addition to their non-volatile memory characteristics, these carbazole-functionalized layers mimic key features of biological synapses under low to moderate biasing. Through the repeated application of voltage pulses, the devices show short-term plasticity (STP) and long-term plasticity (LTP), paired-pulse facilitation (PPF) and depression (PPD), spike-timing-dependent plasticity (STDP), and Hebbian associative learning—traits essential for hardware-based neural networks and cognitive computing. These neuromorphic behaviors are enabled by underlying physical mechanisms such as voltage-triggered conformational transitions, charge carrier trapping and detrapping, and redox-based switching, which have been elucidated using spectroscopic and electrical measurements [1–3].

This work underscores the promise of carbazole-functionalized polymers as active materials for organic memristors. Their multifunctionality—spanning stable memory storage and dynamic synaptic emulation—makes them excellent candidates for next-generation, low-power neuromorphic systems and adaptive artificial intelligence applications. The integration of these organic materials offers a scalable and tunable approach to bridging the gap between biological computation and electronic devices.

References:

1] Y. R. Panthi, A. Pandey, A. Šturcová, and J. Pfleger, et al., Mater. Adv., 2024, 5, 6388–6398.

[2] A. Pandey, A. Chernyshev, Y. R. Panthi, J. Pfleger et al., Polymers, 2024, 16, 542.

[3] Y. R. Panthi, J. Pfleger, A. Pandey, et al., J. Mater. Chem. C, 2023, 11, 17093–17105.

The textile industry is one of the main sectors contributing to water pollution, with dyes being among the most significant pollutants in wastewater. In this study, molecularly imprinted polymers (MIPs) were used for the removal of Direct Green-6 (DG-6), a dye commonly found in textile wastewater. MIPs are artificially synthesized polymers that contain specific binding sites for target molecules. Due to this property, they stand out as an effective method for the selective removal of environmental pollutants.

In this study, DG-6-specific MIPs were synthesized using the bulk polymerization method and optimized with different ratios of MAA (methacrylic acid), EGDMA (ethylene glycol dimethacrylate), and the initiator AIBN (azobisisobutyronitrile). After polymerization, DG-6 was removed from the polymers through washing steps using various methanol/acetic acid solutions. The efficiency of template molecule removal was evaluated using spectrophotometric methods, and the obtained MIP and NIP (non-imprinted polymer) samples were characterized by FT-IR spectroscopy.

As a result of adsorption studies, the most efficient removal was achieved by the polymer synthesized at a 1:50:150 ratio, referred to as “β MIP.” This polymer achieved 46% dye removal after 20 hours of adsorption. The results indicate that MIPs can effectively recognize and remove complex pollutants such as DG-6 dye.

This study demonstrates that molecularly imprinted polymers offer a cost-effective, selective, and environmentally friendly alternative for dye removal from textile wastewater and lays the groundwork for their use in advanced treatment processes.

The development of biobased and biodegradable materials for food packaging is a critical step toward reducing environmental impact and replacing petroleum-derived plastics. In this work, the fabrication and characterization of polyvinyl alcohol (PVA) films incorporating extracts from Muicle (Justicia spicigera) flowers are presented as a green approach to active packaging. Flower extracts were obtained using water and ethanol as solvents, employing decoction and sonication as green extraction methods. The resulting extracts, rich in phenolic and anthocyanin compounds, were mixed with PVA and processed into films through solvent casting. Physicochemical characterization confirmed the successful incorporation of bioactives and showed good film integrity. Antioxidant activity was evaluated using DPPH assays, which revealed an enhanced radical scavenging capacity in films containing ethanolic extracts. To assess antimicrobial potential, the bioactive films were used to package fresh fruit samples, which were placed in sealed glass beakers. Over time, microbiological growth on the fruit surface was monitored and compared to unprotected controls. The results demonstrated a significant reduction in microbial proliferation in the presence of muicle-enriched films, supporting their potential as biobased antimicrobial packaging. These findings demonstrate a viable pathway for integrating botanical bioactives into biodegradable polymer systems, contributing to sustainable material development in food technology and packaging.

When dealing with applications where plastics could be subjected to combustion and fire, the addition of flame-retardant (FR) additives into the polymers becomes a mandatory requirement. While FR systems are designed on purpose depending on several aspects, such as the specific application, the type of polymer, and the various fire risk scenario, their effectiveness in recycled polymers has not yet been systematically elucidated. On the other hand, considering that FR additives are abundantly present in numerous plastic waste streams, their presence can interfere with the mechanical recycling processes, posing significant challenges for the management of end-of-life FR-plastic parts.

In this study, two different approaches were followed in order to assess (i) the effectiveness of an intumescent FR system as flame-retardant for recycled polypropylene (PP); (ii) the possible modification of the combustion behavior of PP/FR during the reprocessing.

To this aim, virgin and reprocessed PP were melt compounded with an intumescent FR composed of piperazine pyrophosphate (PPAP) and melamine pyrophosphate (MPP) and characterised in terms of combustion, thermal and rheological behaviour. Furthermore, PP/FR was subjected to five reprocessing cycles in a twin-screw extruder (trying to simulate a mechanical recycling process) and characterised after each cycle.

Despite the different combustion behavior of reprocessed PP/FR as compared to the virgin one, the intumescent FR still provided satisfactory flame retardancy properties. In fact, the flame retardancy properties remain largely unaffected by repeated processing cycles, resulting in no change in UL94 classification even if the material is reprocessed up to five times.

These results would pave the way for a greater variety of applications for recycled PP, reducing the reliance on virgin plastic and advancing the circular economy of PP-based waste.

Multifunctional drug delivery systems incorporating 5-fluorouracil (5-FU) represent a novel therapeutic strategy in cancer target treatment while minimizing damage to healthy cells. This study aimed to develop and evaluate new hydrogel compositions based on poly(vinylpyrrolidone), carboxymethylcellulose, poly(ethylene glycol), and agar, synthesized and sterilized via e-beam irradiation using a dose of 30 kGy. The cross-linked hydrogels were evaluated in terms of swelling properties in different pH media from 4 to 8, mechanical properties, drug loading capacity, and in vitro drug release and biodegradation profiles. Additionally, the 5-FU release kinetics was investigated using several mathematical models. The swelling results showed that the pH of the solutions had a substantial impact on swelling, as well as on drug loading capacity. Compared to the basic medium (970%), a greater absorption capacity was seen at pH 7.4 (1385%) and in an acidic medium (1200%). In comparison to the loss modulus (G" = 1580 Pa), the hydrogels showed noticeably higher storage modulus values (G' = 36,700 Pa), indicating elastic behavior and confirming the existence of a stable macromolecular network. Notably, this hydrogel demonstrates a higher 5-FU drug-loading capacity of 5.5 mg/g at pH 6, exhibiting a cumulative release profile of 96% at pH 5 and 80% at pH 7.4 within 30 hours. The experimental kinetic data fit best to the Korsmeyer–Peppas, Peppas–Sahilin, and Makoid–Banakar kinetics models with correlation coefficients (r²) above 0.99, revealing a Fickian mechanism transport of 5-FU within the hydrogel matrix. The aforementioned findings show that hydrogel has the potential to be used as an intelligent wound dressing for the treatment of local cancer.

Hydrogels used as local delivery systems are a viable alternative for the local administration of anti-tumor medications to overcome the side effects of oral or intravenous administration induced by chemotherapeutics. Hydrogels are considered the best alternative for cancer treatment because they allow non-invasive release, effectively support the local and gradual release of anticancer drugs, increase drug solubility and bioavailability, offer high stability and controlled drug release, and may also help reduce the total dose required. Herein, we designed and developed a novel semisolid hydrogel composed of collagen gel (calfskin), sodium carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO) using e-beam irradiation as the crosslinking method. According to experimental results of loading and in vitro release, the semisolid hydrogel loaded 1145±1% ng of doxorubicine (DOX) and released different amounts of DOX, such as 120 ± 0.5% ng/cm2 at pH 6.4 and 150 ± 0.2% ng/cm2 at pH 7.4, for a period of 0.5 to 60 hours. In addition to the progressive release of DOX, the hydrogel retains its structure, is transparent, allows observation of the affected tissue, and has elastic properties unique to hydrogel-type systems. The semisolid hydrogel can be used as an absorbent material with regenerative properties and as a biocompatible polymeric matrix for the progressive delivery of DOX, a broad-spectrum anticancer drug.

The mechanical strength, as well as the responsiveness to stimuli, of photosensitive polymers makes these materials exceptionally useful in the reconstruction of hard tissues, although their clinical effectiveness over extended periods of cyclic loading remains unclear. This work systematically reviews 86 research articles that estimate the fatigue life of medical-grade photosensitive polymers using three different techniques: adaptation of the Weibull distribution, Paris–Erdogan crack propagation models, and hybrid statistical–machine learning methods. Data collection comprised standardized bending and tensile fatigue tests performed under physiologically relevant loading conditions. Throughout 2010 to 2024, I found and screened 1247 records while adhering to PRISMA guidelines, eventually yielding 86 studies from sources like PubMed, Google Scholar, and Web of Science. Erdogan models reached accuracy rates of 83–86% (R² range: 0.80–0.84), while the highest performing hybrid statistical–machine learning methods achieved 91–94% accuracy (R² range: 0.88–0.91). These hybrid approaches outshone other models in capturing nonlinear degradation trends in high-cycle fatigue (>10^5 cycles) where traditional models overestimated fatigue life by 12–18%. Regardless of the model used, fatigue resistance was observed to strongly correlate crosslinking density (Pearson’s r = 0.79) and filler composition (r = 0.74). While statistical models have merit, especially during the preliminary stages of design, their predictive accuracy is often limited. In contrast, the machine learning component in hybrid models improved performance under varying load conditions and material complexity, resulting in more clinically reliable estimates of the device lifetime. Key limitations of the study included absent standardized protocols for fatigue testing and difficulties simulating in vivo degradation conditions. Supporting the conclusions of this study are the interdisciplinary efforts required to improve photosensitive polymer fatigue life testing that are guided by real-time clinical predictions and test standardization.