Calcium phosphate coatings with differentiated crystallinity on polyamide scaffolds enable Dual-Stage bone regeneration

Microplastics are of growing concern due to their ubiquity and potential risks to ecosystems and human health. Their small size, chemical diversity, and coexistence with natural colloids make comprehensive analysis difficult. Here, we evaluate two emerging single particle techniques, single particle inductively coupled plasma-mass spectrometry (SP ICP-MS) and optofluidic force induction coupled with Raman spectroscopy (OF2i-Raman), for their ability to provide complementary information at single microplastic resolution. SP ICP-MS determined carbon mass per particle and enabled detection of degradation-induced trends in size and abundance, while OF2i-Raman identified polymer type and molecular changes via optical trapping and inelastic light scattering. OF2i-Raman is a novel method in the field of microplastic research and was therefore first benchmarked by analysing mixed suspensions of polymethylmethacrylate (PMMA), polystyrene (PS), and polyamide-6 (PA-6), as well as PA-6 in a soil extract to assess selectivity under complex matrix conditions. Subsequently, both techniques were applied in parallel to study the UV-induced degradation of PA-6 and low-density polyethylene (LDPE) as relevant industrial polymers. SP ICP-MS detected longitudinal carbon loss and relative changes in particle sizes and numbers, while OF2i-Raman revealed polymer-specific structural alterations and detected spectral fingerprints even after extended irradiation. Together, SP ICP-MS and OF2i-Raman link elemental mass with molecular identity, providing complementary insights into microplastic degradation. While SP ICP-MS remains confined to controlled laboratory experiments due to its limited selectivity and size range, OF2i-Raman extends the analytical window to complex matrices and mixed polymer systems.

Purpose This study aims to enhance the postprocessing of selective laser sintering (SLS)–polyamide 12 (PA12) parts through hot chemical vapor smoothing (CVS) to achieve smoother surfaces and maintain dimensional accuracy suitable for biomedical and wearable assistive device applications. Design/methodology/approach A comprehensive experimental evaluation of the CVS process was performed using a trifluoroacetic acid (TFA)–dichloromethane (DCM) solvent system. A four-factor Face-Centered Central Composite Design (FC-CCD) was used to analyze the effects of TFA concentration, chamber temperature, exposure time and solvent volume on the surface roughness and dimensional accuracy of SLS-fabricated PA12 components. Findings The CVS results showed that exposure time and chamber temperature significantly influenced the surface finish of PA12 parts. Optimized parameters reduced Ra from 11.92 ± 0.34 to 3.45 ± 0.18 µm (71%) and Rz from 51.96 ± 1.42 to 12.57 ± 0.64 µm (76%), while minimizing dimensional deviation by 73%. Scanning electron microscopy revealed smoother, denser surfaces, and energy-dispersive X-ray confirmed that the chemical integrity of PA12 remained stable. Research limitations/implications This study is limited to a specific solvent–material combination for SLS-fabricated PA12 parts, potentially limiting its broader applicability. Future work should explore different solvent systems, more complex geometries and mechanical performance after smoothing. Originality/value This study provides a design of experiments–based optimization of chemical vapor smoothing parameters for SLS–PA12, revealing that solvent concentration, temperature and exposure time govern controlled surface quality.

Polyamides (PAs) exhibit excellent chemical stability and mechanical resistance, yet these same characteristics lead to their widespread accumulation in the environment as pollution. In this work, we developed an inclusive and operationally simple photothermal strategy to recycle PAs, overcoming the high energy barriers necessary to break down these materials. PAs can be depolymerized using photothermally mediated ring-closing depolymerization and acidic hydrolysis to afford cyclic and linear monomers using carbon black as a photothermal agent (PTA) under visible light irradiation. We showed that polyamide 6 is efficiently depolymerized to ε-caprolactam with 74% yield in 10 min. Similarly, in 1 h, the photothermal acidic hydrolysis of polyamide 6,6 afforded hexamethylene diamine and adipic acid with 97 and 96% yields, respectively. This method was further applied to a variety of aliphatic and aromatic PAs and mixed PA waste. Both photothermally promoted processes effectively depolymerize pigment-containing postconsumer waste by leveraging existing black pigments as PTAs. Here, photothermal conversion provided a general and rapid route for PA depolymerization under visible light irradiation, enabling high monomer yields with inexpensive reagents and a general tolerance to additives, demonstrating this approach's potential for a circular plastic economy.

Understanding how plastics degrade and fragment, releasing microplastics, nanoplastics, and dissolved organic carbon (DOC), is crucial for their risk assessment. This study assesses abiotic hydrolytic aging of polymer powders (40-700 μm) under OECD guideline conditions and in simulated seawater from 4 to 65 °C (accelerated aging) over 10, 100, and up to 365 days. Chain scission, recrystallization, fragmentation, and dissolution of microplastics were examined for polyamide-6 (PA-6), thermoplastic polyurethane (TPU), polypropylene (PP), low-density polyethylene (LDPE), and polylactic acid (PLA). Microplastics (1-190 μm) mainly formed through surface cracking, whereas nanoplastics (0.01-1 μm) arose from particle shrinkage and erosion. Polymer chemistry strongly influenced the release patterns, with total degradation and release ranking LDPE < TPU < PA-6 < PLA; stabilized PP ranked lowest, as expected. TPU and LDPE underwent limited hydrolysis but measurable thermo-oxidative modification. PA-6 and PLA were both prone to degradation under high temperatures and specific pH, but with distinct behaviors: PLA showed substantial bulk dissolution, producing diverse DOC species over time, whereas PA-6 released a smaller and temporally stable DOC pool; both polymers fragmented. Overall, abiotic hydrolysis drives interconnected fragmentation and dissolution processes, with release dynamics depending on polymer type and environmental conditions. The resulting data support mechanistic modeling of microplastic fragmentation.

ABSTRACT Polyamide (PA)-based ultrafiltration membranes offer low-cost and energy-efficient separation for wastewater treatment. In this study, nanocomposite PA membranes were synthesized using the non-solvent induced phase inversion (NIPS) technique with controlled thickness (200–400 µm) and incorporation of 0.1 wt.% titanium dioxide (TiO2), copper sulfide (CuS), and xanthan gum (XG) nanoparticles to enhance morphology, hydrophilicity, permeability, and mechanical strength. Nanofiller addition significantly improved the permeability–selectivity balance. The PA@TiO2 membrane exhibited the highest pure water flux of 250 ± 50 L/m2h, nearly ten times higher than pure PA (25 L/m2 h), due to enhanced porosity, improved pore interconnectivity, and Ti-OH functional groups that reduced water transport resistance. The PA@CuS membrane achieved superior BSA rejection of 85.23% compared to 71.89% for pure PA, along with a reduced contact angle of 33.13°, confirming enhanced hydrophilicity. PA@TiO2 also demonstrated 68% NaCl rejection and 56% dye rejection, with effective TSS, COD, and BOD removal in synthetic wastewater. Mechanical analysis showed significant reinforcement, with PA@XG exhibiting the highest tensile strength (3755 Pa). Overall, low nanoparticle loading and scalable NIPS fabrication produced durable, high-performance membranes suitable for sustainable ultrafiltration applications.

Sustainable structural composites can significantly lower vehicle-related emissions. To evaluate the recycling of different composite materials, laboratory-scale pyrolysis was conducted and assessed both technically and environmentally. Two demonstrators were studied: a truck side skirt made from natural flax and hemp fibres with polypropylene (PP), and a car front header composed of glass fibres and PP. Additional materials examined included thermoplastic composites containing polyamide 6 (PA6), bio-based polyamide 11 (PA11) and thermoset polyester. Results showed that material type strongly influenced the pyrolysis outcome, product composition and recycling potential. Glass fibres could be recovered and reused as reinforced fibres, while natural fibres could be recovered as biooil for potential use in biofuel production. Polymers were recovered as pyrolysis products that, depending on their composition, can be used in different applications, from recovering monomers from PA6 to producing hydrocarbons that may replace naphtha (from PP) or aromatics (from polyester) in the petrochemical industry. Life cycle assessment (LCA) findings revealed that the climate impact of composite recycling is primarily driven by the environmental burdens of the recycling process itself and by the ability of recovered materials and chemicals to substitute conventional fossil-based alternatives. Efficient recycling pathways are therefore essential to maximising environmental benefits.

ABSTRACT Post‐spinning processing profoundly influences the mechanical performance of polyamide 6 (PA6) fibers by reshaping their condensed structure. Herein, multistage drawing and heat‐setting post‐spinning processes were applied to as‐spun PA6 fibers prepared via industrial scale melt spinning. Fibers were obtained via both in‐process sampling at different stages of a single post‐spinning process and end‐product sampling under varied process parameters. DSC, FTIR, WAXD, and orientation characterization were utilized to track the evolution of the condensed structure, while mechanical properties and dry heat shrinkage were assessed to establish the structure‐performance relationship. During the two‐stage drawing, the crystallinity and orientation of fibers continually improve, accompanied by the transformation of metastable γ‐phase and amorphous phases to stable α‐phase. Increasing the drawing ratios enhances the content of rigid structures, thereby boosting fiber strength but elevating dry heat shrinkage. Two‐stage heat‐setting alleviates the internal stress induced by drawing. A moderate relaxation rate (2.50%) facilitates phase transition, enhancing crystalline perfection and balancing strength with shrinkage. In contrast, a 3.00% relaxation rate disrupts the crystalline structure and orientation, thereby impairing the overall fiber performance. This study provides a theoretical foundation for regulating PA6 fiber structure and properties, supporting industrial process optimization and high‐performance fiber development.

Abstract Microplastics (MPs), recognised as emerging contaminants, are increasingly prevalent in riverine ecosystems due to escalating anthropogenic activities. River deltas, which typically serve as ecologically rich and pristine habitats, are now under threat from solid and liquid waste inputs, particularly in rivers flowing through urban and agricultural landscapes. This research investigates MP contamination in sediments of the Brahmani River within the Bhitarkanika Wildlife Sanctuary, Odisha (India), encompassing both mangrove and non-mangrove sites. The highest recorded abundance was 50.4 items/kg dry weight (dw) and 25 items/kg wet weight (ww), with fibers, fragments, and films as the dominant morphotypes. Across most sites, fibers in the 0.1–5 mm size range were predominant. Polymer identification by ATR-FTIR revealed a predominance of polyamide (PA), followed by low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP). SEM–EDS analyses revealed that MPs had surface-adsorbed heavy metals (HMs), including chromium, copper, zinc, arsenic, cadmium, barium, and lead, which were sourced from the surrounding riverine environment. Risk assessment indices, including contamination factor (CF), polymer hazard index (PHI), potential ecological risk index (PERI), and pollution load index (PLI), indicated high ecological risk at several sites. High ecological risk indices were observed, raising serious concerns for elephants that depend on the river for drinking water. Ecological functioning in the Brahmani River in Bhitarkanika Wildlife Sanctuary supports saltwater crocodiles, Olive Ridley turtles, and other native and migratory birds. Mangrove sediments were identified as significant sinks for MPs, with the potential to disrupt benthic communities and impair mangrove productivity. This research will help ecologists, policymakers, NGOs, and state and federal governments develop policies and regulations to protect the Brahmani River, which supports the ecological functions of Bhitarkanika Wildlife Sanctuary and Bhitarkanika National Park. Graphical Abstract

To address the urgent requirement for antifouling reverse osmosis (RO) membranes, this work presents an innovative interfacial polymerization (IP) strategy utilizing molecularly engineered zwitterionic surfactants. Three zwitterionic surfactants with identical hydrophilic heads but distinct hydrophobic tails were synthesized, each serves a dual function: regulating IP kinetics while incorporating into the polyamide (PA) network to confer inherent antifouling properties. The surfactant combining an aromatic ring and a long alkyl chain proved most effective, enhancing integration via π-π interactions and maximizing interfacial activity to yield a polyamide layer with superior density, hydrophilicity, and permeability. The resulting membrane achieves a balance of high water permeance (2.7 LMH/bar), outstanding salt rejection (99.6%), and excellent antifouling performance. In practical tests using real coking wastewater, it consistently outperformed a leading commercial antifouling membrane (DuPont FilmTec CR100) across multiple fouling-cleaning cycles. This study establishes a new paradigm in which tailored surfactant molecular design directly governs RO membrane properties and integrated performance, offering a promising pathway to next-generation RO membranes for challenging water treatment applications.

Airborne micro- and nanoplastics (MNPs) are emerging pollutants of concern due to their widespread presence, inhalation exposure risks, and potential ecological and human health impacts. In this study, pyrolysis-thermal desorption-gas chromatography-mass spectrometry (Py-TD-GC-MS) was applied to quantify MNPs (PP, PE, PS, PVC, and PET) in PM2.5, PM10, and total suspended particulate matter (TSP) collected during the non-heating and heating seasons in Beijing. The average concentrations of MNPs in PM2.5, PM10, and TSP during the non-heating season were 0.21 ± 0.05 μg/m3, 0.45 ± 0.20 μg/m3, and 0.84 ± 0.42 μg/m3, respectively, rising to 0.41 ± 0.12 μg/m3, 1.23 ± 0.58 μg/m3, and 2.30 ± 0.75 μg/m3 during the heating season, with polyethylene (PE) dominating all size fractions (>50%). Complementary vibrational spectroscopy results confirmed the presence of additional polymers, including polyamide (PA) and poly(methyl methacrylate) (PMMA), highlighting the value of multimethod approaches for comprehensive characterization and the ongoing need to develop new analytical techniques. Exposure assessment indicated daily per capita inhalation of outdoor MNPs in urban Beijing at 60-344 ng during the non-heating season and 374-926 ng during the heating season. This study provides the first size-resolved, multimethod assessment of airborne MNPs in a northern Chinese megacity, with a comparative analysis between heating and non-heating seasons.

Polyamide-12 (PA12) dominates the Polymer Laser Powder Bed Fusion (P-LPBF) material market, with limited alternatives. Functionalising polymers, such as PA12, with nanomaterials to create nanocomposite powders can enhance and diversify part properties. Open-chain end PA12s are commonly used as the matrix polymer, however, the unfused powder is typically only ~50% reusable and their poor re-useability can be exacerbated when functionalised using nanomaterials. Unfused end-passivated (closed chain end) PA12s are ~90% reusable as they resist process-related degradation/ageing better than open-chain end PA12s, enabling a near zero wastage P-LPBF workstream. However, the relatively narrow parameter space of end-passivated PA12s is perceived to require precise and challenging process control. Nanomaterial-based functionalisation is known to alter P-LPBF processability of open-chain end PA12s. Such an alteration risks rendering the end-passivated PA12s unsuitable for P-LPBF; hence, despite their better reusability, nanomaterial functionalisation of end-passivated PA12s has generally been avoided until now. Using MWCNTs as an example, we demonstrate nanocomposite powder preparation and P-LPBF processing using ~90% reusable end-passivated PA12. An unconventional approach of setting the powder bed temperature above the melting onset temperature of the powder has been shown not to require any challenging process control as previously perceived. A comprehensive energy density calculation metric, Effective Mass Energy Density (EMED), has been proposed and used to explain the impact of material properties and process parameters on part properties. The drastic increase in reusability without compromising processability opens the doors to a larger material palette using more exotic nanomaterials while lowering cost, waste and carbon footprint.

Microplastics modulate triclosan abiotic methylation: Effects of polymer type and photoaging.

Features of obtaining bentonite-based ceramic support using SLS 3D printing

Overcoming property trade-offs in colorless polyimides: A molecular composite strategy for simultaneous optical transparency, mechanical robustness, dimensional stability, thermal resistance, and electrical insulation

Modification of thin-film nanocomposite forward osmosis membranes with an antimicrobial carboxymethyl starch-ZnO@MOF-199 nanocomposite for heavy metals and dyes pollutants removal.

MXenes (2D transition metal nitrides, oxycarbides, carbonitrides, and carbides) hold promise in water treatment due to tunable surface chemistry and hydrophilic nature but restacking in aqueous environments and susceptibility to oxidation remain challenging. Here, we deliberately exploit partial oxidation of Ti 3 C 2 T x MXene to in situ grow TiO 2 nanoparticles on its surface, creating a porous, phase-engineered MXene-TiO 2 composite. The anatase:rutile ratio was adjusted through different hydrothermal process time (12, 18, and 24 h), after 18 h composition yielding the best balance of surface charge and structural stability. This composite was incorporated into the polyamide (PA) layer of a thin-film composite reverse osmosis (TFC RO) membrane at optimized loadings. Compared to the pristine membrane, the optimized membrane showed a 5.3-fold increase in permeance (reaching 21.8 ± 0.3 L m −2 h −1 bar −1 ). At environmentally relevant PFAS concentration, rejection of short-chain PFBA reached 96.9 ± 1.8% and of long-chain PFOA 98.8 ± 0.3%. Performance of fabricated membranes was tested in the presence of Ca 2+ , humic acid, their mixture, and cetyltrimethylammonium bromide (CTAB) in the background (maintaining >95% removal). ICP analysis after continuous filtration (10 days) detected no Ti in permeate, indicating strong integration or embedding and chemical bondings to membrane. Extended fouling tests demonstrated sustained permeance and rejection under realistic conditions. This work presents a practical route to overcome MXene restacking and oxidation, delivering a high-performance RO membrane for efficient PFAS removal under practical operating scenarios. • Phase-engineered MXene-TiO 2 composites synthesized via controlled partial oxidation • Optimized membrane reached 21.8 LMH/bar permeance and 98.8% PFOA rejection rate • PFBA rejection rate increased in the presence of Ca 2+ ions and CTAB • Co-presence of humic acid-Ca 2+ ions lead to severe fouling of unmodified membrane • Optimized membrane retained 94% of its initial permeance and rejection over 10 days

Spatial distribution, abundance, and characterization of emerging plastic forms in binational coastal ecosystems.

Adsorption of heavy metals by microplastics in aquatic environments: mechanism, multi-factor regulation and ecological risks.

Long-fiber thermoplastic (LFT) materials are a versatile category of composite materials that can be directly compounded (LFT-D) in twin screw extruders and compression molded. Originating in the automotive sector, the LFT-D process is becoming increasingly attractive for other industries where low cycle times, lightweight performance and recyclability are required. The purpose of this work is to summarize mechanical properties and findings from the investigations into LFT-D process-microstructure-property relationships and present a design of experiments (DoE) study based on the current state of the art. Primary parameters from LFT-D compounding, screw speed, fiber roving amount and polymer throughput mp are chosen as DoE factors. Polyamide 6 (PA6) is reinforced with a glass fiber (GF) mass fraction wf between wf = 20% and wf = 60%. Tensile, flexural and impact properties are chosen as DoE output parameters, characterized and discussed in relation to the state of the art. The unique microstructure of LFT-D materials, especially the existence of a charge and flow area as well as the fiber migration, is considered in the discussion. All mechanical properties characterized have a linear relation to wf. This study demonstrates the interactive relationship between the main factors and wf, which significantly influences the mechanical properties. This dependence of wf on the DoE factors is accounted for in advanced response contour plots proposed in this work. Parameter recommendations for the screw speed are reported by ranges of wf and polymer throughput for the goal of maximum mechanical properties or low coefficient of variations. At wf < 30% a low screw speed is recommended to improve most mechanical properties as well as the coefficient of variation.