This work presents the demonstration of phosphonamidate-derived covalent adaptable networks (CANs), offering a promising strategy to overcome the traditional trade-off between sustainability and fire safety in thermoset materials. We introduce phosphonamidate-based curing agents that integrate epoxy curing, intrinsic flame retardancy, and dynamic bond exchange within a single molecular design. These curing agents enable the formation of epoxy-based CANs that can be reprocessed multiple times without loss of performance, enabled by an efficient trans-phosphonamidate exchange mechanism at the P-O bond. The phosphonamidate structure further promotes faster bond exchange relative to other phosphorylated networks, facilitating dynamic network rearrangement. Beyond recyclability, the intrinsic phosphorus-nitrogen framework provides excellent fire resistance, achieving UL-94 V-0 ratings at only 2 wt % phosphorus loading while significantly reducing peak heat release. Importantly, the flame-retardant performance remains stable after repeated recycling, demonstrating the robustness of this approach. Thermal and mechanical analyses reveal tunable glass-transition temperatures, high thermal stability, and durable performance over five recycling cycles. To demonstrate application potential, carbon-fiber-reinforced composites were fabricated, confirming that these CAN systems can be processed into high-performance structural materials. Overall, phosphonamidate hardeners provide a versatile platform for thermoset resins and composites requiring recyclability, fire safety, and structural performance.

Silica–polymer composites are widely used to enhance mechanical performance in industries ranging from packaging to transportation. However, extending their use into high-demand sectors such as electronics and construction requires additional functionalities, particularly transparency and fire safety. Here, we demonstrate both by developing fully transparent, self-extinguishing silica–epoxy nanocomposites (SiEpo-NCs) via an in situ sol–gel process. Using a Novolac epoxy matrix cured with a cycloaliphatic hardener, we obtained uniformly dispersed amorphous silica nanoparticles (SNPs), as confirmed by microscopy and particle size analysis. An alternative masterbatch-dilution route produced silica-rich and silica-free domains, which further enhanced the thermo-mechanical performance of the composite materials. To achieve flame retardance while maintaining optical clarity, we incorporated the liquid phosphorus-based additive 6H-dibenz[c,e][1,2]oxaphosphorin-6-propanoic acid, butyl ester, 6-oxide (DOB) into the SiEpo network. This strategy yielded a UL94-V0 classification at only 3 wt.% phosphorus and 2 wt.% SNPs, delivering a rare combination of transparency, non-dripping behavior, and self-extinguishing performance. Cone calorimetry and gas analysis revealed a synergistic mechanism between SNP-induced char formation and DOB’s gas-phase inhibition, establishing a promising route toward multifunctional epoxy nanocomposites.

Covalent adaptable networks (CANs) are predominantly employed as bulk polymer matrices, while their potential as dynamically crosslinked functional additive phases within conventional thermoplastics remains largely unexplored. Here, phosphorus-containing CANs (P-CANs) with systematically varied molecular architectures are employed as durable functional additives for polyamide 6 (PA6), enabling network architecture to be related to additive dispersion, retention, melt processability, and functional performance. Transitioning from a rigid, small-molecule-derived network to flexible polyphosphonate-based architectures tunes the glass transition temperature from 160 to -5 °C and markedly alters network dynamics and dispersion during melt processing. The rigid P-CAN forms larger phosphorus-rich domains in PA6, whereas the most flexible architecture exhibits substantially more homogeneous dispersion, reduced processing resistance, and pronounced shear-thinning behavior. This balance enables translation from laboratory-scale screening to pilot-scale twin-screw compounding and continuous extrusion of uniform PA6 films containing 5–10 wt% CANFR15. Despite low final phosphorus contents of only ~0.25–0.60 wt%, P-CAN incorporation increases the limiting oxygen index of PA6 from 25.8% to as high as 33.0%, promotes char formation, and reduces peak heat release measured in microscale combustion calorimetry. Embedding phosphorus within the CAN architecture additionally suppresses its extraction relative to conventional phosphorus-containing additive flame retardants under accelerated solvent-leaching conditions. These results establish molecular architecture as a key design parameter for balancing network rigidity, additive dispersion and retention, functional performance, and melt processability, while demonstrating P-CANs as a promising class of durable macromolecular additives for scalable thermoplastic processing.

Thermosetting polymers are widely employed in high-performance applications owing to their excellent mechanical properties, thermal stability, and chemical resistance. However, their permanently crosslinked architecture severely limits recyclability, while their intrinsic flammability remains a major concern for safety-critical applications. Herein, hybrid epoxy–amino ester covalent adaptable networks (CANs), incorporating phosphorus-containing polyelectrolyte complex (PEC) micro-particles, are developed to simultaneously address these two challenges. The hybrid network combines associative transesterification and dissociative retro Aza-Michael addition exchange reactions, enabling efficient thermomechanical reprocessing while preserving the crosslinked architecture. The incorporation of PEC, prepared through a simple aqueous process from poly(allylamine hydrochloride) and sodium polyphosphate, provides an environmentally friendly phosphorus-nitrogen flame-retardant additive without altering the curing behavior or dynamic network properties. The resulting materials exhibit stable glass transition temperatures, efficient stress relaxation, and excellent retention of thermal properties after recycling. An optimized phosphorus loading of 3 wt% enables the material to achieve a UL-94 V-0 classification, while maintaining its flame-retardant performance after thermomechanical recycling. In contrast, equivalent formulations containing commercial ammonium polyphosphate (APP) flame retardant failed to achieve a UL-94 V-0 classification, even at 4 wt% phosphorus, demonstrating the superior flame-retardant efficiency of PEC. Finally, carbon-fiber-reinforced composites fabricated using the developed matrix demonstrate excellent flexural properties, highlighting the potential of these recyclable flame-retardant CANs for sustainable structural applications.

Anodic aluminum oxide (AAO) mesoporous membranes functionalized with alpha-diimine Ni(II) complexes were recently considered as nanoscale chemical reactors for confined-space polymerization of ultra-high molecular weight, low-branched polyethylene. One of the factors regulating the structure-property relationship of the polymer is the spatial distribution of Ni single-atom catalysts present inside the membrane's nanochannels. The grafting of the Ni complex inside the nanochannels occurs via the functional linker trimethylaluminum. Here, we employ X-ray photoelectron spectroscopy (XPS) to investigate and quantify both the distribution and absolute surface concentrations of the catalyst inside and along the nanochannels across the membrane. Up to 0.6 catalyst molecules/nm2 have been detected in the middle of the nanochannels. This value corresponds to approximately 80% of the maximal monolayer surface coverage of 0.73 catalyst molecules/nm2 found outside the pores, i.e. on the flat membrane surface. This work not only demonstrates that it is possible to graft functional catalysts inside the confined space of nanochannels, but it also quantifies their surface concentrations. This quantitative mapping establishes a critical foundation for the design of nanochannel reactors with tailored catalyst distributions. We found catalyst density gradients along the nanopores that could be useful to vary the density of polymerization sites along these nanochannels.

Polymeric materials are vital in modern life due to their versatility and cost-effectiveness. Thermosets are highly valued for their exceptional durability, chemical resistance, and mechanical strength. Despite these advantages, challenges such as enhancing fire safety and recyclability persist. Covalent Adaptable Networks (CANs) offer a promising solution, providing a sustainable platform for materials with self-healing and recyclable properties. This study addresses these challenges by developing innovative CANs through Aza-Michael addition and retroaddition chemistry. Amino-ester networks (AE) composed of m-Xylenediamine, and pentaerythritol triacrylate were manufactured while simultaneously incorporating phosphorus-based flame retardant (FR) additives synthesized in situ. A systematic characterization of physical, thermal, flame-retardant, and reprocessability properties was performed for the novel AE. Ten thermomechanical recycling cycles were performed for the AE to demonstrate the robustness of the new material, showing no degradation or changes in its physical, thermal, and flame-retardant properties. The chemistry involved in the recyclability was characterized via Raman Spectroscopy. The thermoset containing 0.7 wt% phosphorus (P) exhibits self-extinguishing behavior, achieving a V0 rating. Compared to the material without flame retardant additives, the presence of the new in-situ FR (3.6 wt % P) allows for a significant reduction in total heat release (43%) and total smoke release (46%). The new FR molecule was also compared with a similar, previously reported molecule (EDA-bis-TEPT) and showed significantly better flame-retardant properties. Furthermore, the potential of these innovative thermosets was explored for applications such as fire-safe carbon fiber-reinforced composites, indicating a promising direction for developing sustainable and high-performance polymer materials.

The closed-loop recycling of thermoset plastics remains a critical challenge, especially as demand grows for materials that combine high performance with fire safety. This study presents a new class of inherently flameretardant epoxy thermosets (ETs) incorporating reactive polyphosphonates as co-monomers. The resulting amine-cured ETs achieve UL94 V-0 ratings at just 2.5 wt% phosphorus loading, alongside excellent mechanical and thermal performance (Tg = 140-175 degrees C, tensile strength = 100-110 MPa, modulus = 3.8 GPa). Remarkably, these ETs enable repeated thermomechanical reprocessing, up to ten cycles, without significant loss of performance. When cured with acid anhydrides, the polyphosphonate-based ETs undergo complete chemical depolymerization via alcoholysis, in stark contrast to conventional amine-cured systems. This recyclability extends to carbon-fiber reinforced composites (CFRCs), allowing both carbon fiber recovery and matrix regeneration. These results highlight a promising route toward sustainable, high-performance thermosets with intrinsic flame retardancy and closed-loop recyclability.

Urinary tract infections (UTIs) are among the most common bacterial infections, affecting approximately 150 million people worldwide each year. Currently, diagnosis is often made using culture-based methods, which are time-consuming and therefore costly. Point-of-care (POC) devices have the potential to provide a rapid and accurate UTI diagnosis, thereby improving treatment efficacy. In this work, we developed a fast, specific, and accurate colorimetric sensor capable of indirectly detecting Enterococcus faecalis in urine samples by targeting its metabolite, L-lactate. The sensing probe consists of silica nanoparticles (SNP) loaded with MnO2 (MnSNP), functionalised on the surface with the enzyme lactate oxidase (Lac@MnSNP). The sensor enables both qualitative analysis - through a visible colour change - and quantitative analysis, using spectroscopy. The morphology and composition of the probe were characterised at each synthesis step, confirming that the incorporation of MnO2 into SNP and subsequent enzyme functionalisation did not alter nanoparticle morphology. Lac@MnSNP demonstrated responsiveness to L-lactate, showing a linear decrease in signal up to 50 μM of the analyte, with a limit of detection of 31 μM. The probe successfully detected E. faecalis in artificial urine medium and in complex samples at concentrations as low as 103 CFU mL-1 within 5 h. These results demonstrate the potential of this probe for fast, accurate, and lactate-specific diagnoses.

Achieving lower heat release rates (HRR) during combustion is one of the key steps toward obtaining flame retardant materials. UPR thermosets, while mechanically strong and chemically durable, show high HRR upon ignition. While most commercial applications focus on blending of metal oxide or other heterogeneous fillers to reduce HRR, they have significant drawbacks like phase segregation, drop in transparency and other features which disfavor their use in UPRs. Herein, a novel, green technique to generate nSiO2 in-situ in UPRs is demonstrated. The method is designed such that the precursors act as nucleating agents covalently bonded to the UPRs and as growth fuel for the nSiO2 production. Apart from major advantages like a uniform phase distribution in the thermoset and transparency, this technique also prevents direct handling of powdered micro or nanoparticles, leading to a safer working environment for the handling of UPRs. The physical, thermal, and mechanical properties analyzed show great promise towards flame retardant composites, as the formed nanocomposite material, with 10 wt% loading of nSiO2 demonstrates a 41% reduction in total heat release (THR) and a 52% reduction in total smoke release (TSR), while retaining optical transmission >90%. On combination with commercial phosphorus containing flame retardant, ammonium polyphosphate (APP), the composite shows an even greater reduction in THR and TSR, while also being self-extinguishing. These compelling features, coupled with the safe nature of generating nanoparticles in-situ, offer substantial benefits of using this nSiO2 approach towards HRR reduction in UPR-based thermosets and advocate for their use in commercial formulations.

Polymeric materials are integral to modern life, offering unparalleled versatility and affordability. Among them, thermosets stand out for their remarkable durability, chemical resistance, and mechanical strength. However, these materials face two critical challenges: achieving fire safety and enabling recyclability. This study presents a groundbreaking approach to address both issues simultaneously. By developing a novel family of bisphosphonate ammonium salt (PS), we have created advanced epoxy-based vitrimers (EV). These innovative hardeners not only enhance fire resistance and promote recyclability through a trans-phosphonate exchange mechanism but also exhibit latent curing behavior, desired in various industrial applications. The chemical, mechanical, thermal, and flame-retardant properties of the newly developed EV were assessed. To assess the durability of the newly developed material, it was subjected to five thermomechanical recycling cycles. Throughout these cycles, no signs of degradation or alterations in its physical, thermal, or flame-retardant properties were observed, confirming its robustness. Incorporating 2 wt% phosphorus, the thermoset demonstrated both self-extinguishing and intumescent characteristics, earning a V-0 classification in flammability testing. Compared to the blank reference material, the formulation with the novel bis-phosphonate ammonium salt achieved a substantial decrease in total heat release by 43 % and peak heat release rate by 73 %. To demonstrate the potential applications and sustainability of our new material, high-performance carbon-fiberreinforced composites (CFRCs) were prepared, and their mechanical properties were investigated.

A novel single-atom Ni(II) catalyst ( Ni-OH ) is covalently immobilized onto the nano-channels of mesoporous Santa Barbara Amorphous (SBA)-15 particles and isotropic Anodized Aluminum Oxide (AAO) membrane for confined-space ethylene extrusion polymerization. The presence of surface-tethered Ni complexes ( Ni@SBA-15 and Ni@AAO ) is confirmed by the inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray photoelectron spectroscopy (XPS). In the catalytic spinning process, the produced PE materials exhibit very homogeneous fibrous morphology at nanoscale (diameter: ~50 nm). The synthesized PE nanofibers extrude in a highly oriented manner from the nano-reactors at ambient temperature. Remarkably high M w (1.62×10 6  g mol −1 ), melting point (124 °C), and crystallinity (41.8 %) are observed among PE samples thanks to the confined-space polymerization. The chain-walking behavior of surface tethered Ni catalysts is greatly limited by the confinement inside the nano-channels, leading to the formation of very low-branched PE materials (13.6/1000 C). Due to fixed supported catalytic topology and room temperature, the filaments are expected to be free of entanglement. This work signifies an important step towards the realization of a continuous mild catalytic-spinning (CATSPIN) process, where the polymer is directly synthesized into fiber shape at negligible chain branching and elegantly avoiding common limitations like thermal degradation or molecular entanglement.

Upcycling is emerging as a crucial strategy for enhancing the value of polymers, driving the transition toward a circular material economy. In this study, we present a facile chemical method for converting high-density polyethylene (HDPE) waste into valuable long-chain dicarboxylic acids (LCDCAs) via a key enabling unsaturated double-bond formation step. That is, we propose introducing unsaturation points in HDPE using commercially available heterogeneous catalysts (e.g. Pt/Al2O3). The unsaturation level through C=C double bond formation is around 10%, as confirmed by FTIR, Raman and X-ray photoelectron spectroscopy. A process of microwave-assisted oxidation is demonstrated to break down the dehydrogenated HDPE into a mixture of aliphatic diacids. This approach enhances the recyclability and value of HDPE by the transformation of polymer waste into bifunctional monomers for potentially novel polyester synthesis. This process offers a sustainable and value-added alternative to conventional recycling methods. While further optimizations are needed, initial estimates of the E-factor and sEF provide promising indicators of the potential environmental benefits of this upcycling approach.

Hexamethyldisiloxane (HMDSO) low-pressure plasmas are known for their versatility in the deposition of plasma polymer films (PPFs) with different properties and applications. Although they have been studied for decades, the reaction mechanisms of plasma polymer formation leave open questions, particularly when deposition on 3D materials with complex geometries such as cavities and undercuts is considered. In the present study, two configurations named "cavity" and "undercut" have been selected to study the influence of diffusion of film-forming species and surface reactivity in HMDSO plasmas without and with O2 admixture. A varying spatial chemical composition of the plasma polymer deposit along the penetration depth of the studied configurations indicates different sticking probabilities of the film-forming species. Furthermore, although ion-induced effects are usually only considered for direct plasma exposure, the obtained results and additional etching experiments reveal that the contribution of high-energy particles might still be considered underneath small openings. Finally, the relevance of oxidizing chemical reactions at the surface inside the configurations is clarified when O2 is added to the plasma.

The heterogeneous surface support can play a key role in determining polymer microstructure, as we show for a novel variant of Ni-catalyst from the family of late-transition metal complexes; this extends the toolbox for novel catalytic solutions in industrial processes. Novel variants of single-atom catalysts (Ni-FO-Al@SiO2, Ni-FOSi@SiO2, Ni-O-Al@SiO2, and Ni-O-Si@SiO2) were prepared in the form of unsymmetrical a-diimine Ni complexes (Ni-OH and Ni-FOH) and then characterized by inductively coupled plasma - optical emission spectrometry (ICP-OES) and X-ray photoelectron spectroscopy (XPS) analysis. Ethylene slurry-phase polymerization was performed both via self-supporting and covalent-tethering strategies to systematically study the surface confinement effects. High catalytic activity was maintained under the slurry-phase polymerization (as high as 3.9 x 106 g of PE (mol of Ni)-1 h-1). The crucial features of high molecular weight (>106 g mol-1) and high branching density (as high as 180.1BD/1000C) were found among the PE samples produced via heterogeneous polymerization. A detailed investigation suggested that surface functional groups, such as -OH and -Cl, coordinate with the active Ni species via their lone pairs and terminate the ethylene polymerization. Microstructure analysis of the PE confirm that the supporting substrate provides the chance to modulate the chain-walking behavior of these Ni catalysts. Systematic high-temperature 1H and 13C NMR analysis indicated that the PE branching density could significantly decrease by surface confinement from the solid substrate. Until now, such microstructure control has been mainly realized via the laborious synthesis of bulky a-diimine ligands.

To enable a rapid-acting antibacterial mechanism without the release of biocidal substances, TiO2 catalysts have been considered based on the generation of reactive oxygen species (ROS). Doping with dissimilar metals generates electron-hole pairs with narrow band gaps promoting the production of ROS. Here, plasma technology is investigated to deposit Ag nano islets on defective TiOx films, stabilized by plasma postoxidation suppressing Ag ion release. Importantly, ROS generation is maintained upon storage in the dark yet with diminishing efficacy; however, it can be restored by exposure to visible light. The rapid-acting antibacterial properties are found to strongly correlate with ROS generation, which can even be maintained by functionalization with hydrophobic plasma polymer films. The cytocompatible coatings offer promising applications for implants and other medical devices.

Low-pressure plasma etching of a recycled polyethylene terephthalate (PET) film is studied in comparison to virgin PET and polypropylene (PP) using a capacitively coupled radio frequency (RF) plasma reactor. Recycled polymers are distinguished by increased impurity content and weakened mechanical properties, both affecting plasma etching and adhesion processes. Mild plasma conditions have been selected to maintain the material bulk properties of the polymers. The etch rates and the morphology of the polymer samples were thus determined at floating potential compared with etching at the RF electrode for varying argon/oxygen gas mixtures, etching duration, and sample size. Thermoanalytical and X-ray techniques were used to characterize the polymer before and after the plasma etching treatment. Finally, adhesive-tape peel tests proved that excellent adhesion of silver coatings can also be achieved on a plasma-treated recycled PET film.