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Epoxy resin (EP)/cyanate ester (CE) copolymer, an important structural material with high temperature resistance and low dielectric constant in aerospace, microelectronics, and related fields, is still of great flammability danger. In this work, copper phenyl phosphonate (CuPP), a flame retardant used in EP/CE copolymer was synthesized by the reaction of phenyl phosphonic acid and copper nitrate trihydrate. The fire and thermal behavior of EP/CE/CuPP composites were studied in detail. The results suggested that the UL-94 rating and limiting oxygen index of EP/CE composite with 5 wt% CuPP (EP/CE/CuPP5) reach V-1 level and 30.6%, respectively. Compared with pure EP/CE copolymer, the peak heat release rate and total heat release values of EP/CE/CuPP5 decreased by 34.5% and 18.9%, respectively. The glass transition temperature of EP/CE/CuPP composite is higher than that of pure EP/CE copolymer, suggesting that the fire-retardant composite has higher work temperature and better heat resistance.

The flame-retardant poly(lactic acid) (FR-PLA) fibers with different contents of modified α-zirconium phosphate (α-ZrP) and polysulfonyldiphenylene phenyl phosphonate (OP) were prepared by melt spinning. The organic modification of α-ZrP was characterized by Fourier transform infrared spectroscopy, wide angle X-ray diffraction, and thermo gravimetric analysis. The limiting oxygen index, vertical burning test, and cone calorimeter test were used to investigate the synergistic effect of OP/α-ZrP on flame-retardant property of FR-PLA, the test results suggested that the combustion of PLA fibers was efficiently inhibited by OP/α-ZrP. The results of scanning electron microscopy, Raman spectrum, and X-ray photoelectron spectroscopy indicated that the flame-retardant mechanism of OP/α-ZrP mainly depended on condensed phase. The tensile strength and morphology of FR-PLA fibers with OP/α-ZrP were better than those of fibers treated only with OP, demonstrating that α-ZrP could significantly improve the mechanical property of FR-PLA fibers.

The fire resistant poly(lactic acid) fibers with polysulfonyldiphenylene phenyl phosphonate flame retardant were prepared by melt spinning. The rheology property and spinnability of samples were measured by a capillary rheometer and recording the number of fiber breakage during a 30-min melt spinning. The thermal stability and combustion behaviors of fibers were investigated by Thermogravimetric Analysis, Limiting Oxygen Index and Vertical Burning tests, respectively. It was found that the flame retardation and anti-dripping performance of PLA were distinctly improved by OP. The pyrolysis behavior of fibers was tested by a Pyrolysis-Gas Chromatography-Mass Spectrometry, the structure and degree of graphitization of char residue were analyzed by Scanning Electronic Microscopy and Raman Spectroscopy. The results suggested that OP can promote the forming of char layer on the surface of PLA matrix during burning. The miscibility and spinnability of PLA was negatively affected by OP and the breaking strength of FR-PLA fibers dropped from 3.30 to 2.30 cN/dtex at the presence of 10 wt. % OP.

Tin (IV) phosphates of the class of tetravalent metal acid (TMA) salts have been synthesized by sol–gel method. The functionalized materials of tin (IV) phosphate (SnP) like chromotropic acid anchored tin phosphate (SnPCA) and tin phenyl phosphonate (SnPP) were also synthesized. These materials have been characterized for elemental analysis (ICP–AES), thermal analysis, X-ray analysis and FTIR spectroscopy. Chemical resistivity of these materials has been accessed in acidic, basic and organic solvent media. The proton present in the structural hydroxyl groups indicates good potential for TMA salts to exhibit solid-state proton conduction. The transport properties of these materials have been explored by measuring specific proton conductance at different temperatures. Based on the specific conduction data and Arrhenius plots, a suitable mechanism has been proposed.

Highlights The as-fabricated waterborne polyurethane (WPU) nanocomposite film exhibits a 55.6% improvement in limiting oxygen index, 66.0% and 40.5% reductions in peak heat release rate and total heat release, respectively, and 93.3% increase in tensile strength relative to pure WPU film. The resultant WPU nanocomposite film presents a high thermal conductivity ( λ ) of 12.7 W m −1  K −1 and a low dielectric constant ( ε ) of 2.92 at 10 6  Hz. To adapt to the trend of increasing miniaturization and high integration of microelectronic equipments, there is a high demand for multifunctional thermally conductive (TC) polymeric films combining excellent flame retardancy and low dielectric constant ( ε ). To date, there have been few successes that achieve such a performance portfolio in polymer films due to their different and even mutually exclusive governing mechanisms. Herein, we propose a trinity strategy for creating a rationally engineered heterostructure nanoadditive (FG@CuP@ZTC) by in situ self-assembly immobilization of copper-phenyl phosphonate (CuP) and zinc-3, 5-diamino-1,2,4-triazole complex (ZTC) onto the fluorinated graphene (FG) surface. Benefiting from the synergistic effects of FG, CuP, and ZTC and the bionic lay-by-lay (LBL) strategy, the as-fabricated waterborne polyurethane (WPU) nanocomposite film with 30 wt% FG@CuP@ZTC exhibits a 55.6% improvement in limiting oxygen index (LOI), 66.0% and 40.5% reductions in peak heat release rate and total heat release, respectively, and 93.3% increase in tensile strength relative to pure WPU film due to the synergistic effects between FG, CuP, and ZTC. Moreover, the WPU nanocomposite film presents a high thermal conductivity ( λ ) of 12.7 W m −1  K −1 and a low ε of 2.92 at 10 6  Hz. This work provides a commercially viable rational design strategy to develop high-performance multifunctional polymer nanocomposite films, which hold great potential as advanced polymeric thermal dissipators for high-power-density microelectronics.

Different titanium phosphonates were in situ synthesized within a polymer matrix via non-hydrolytic sol-gel reactions to elaborate nanocomposites with 10 wt% filler content. Titanium tetraacetate was used as titanium dioxide precursor. Three diethyl phosphonates with different organic groups were selected depending on the polymer medium, polypropylene or polystyrene respectively. Polymer/titanium phosphonate nanocomposites obtained were characterized by TGA, FTIR and 31 P solid-state NMR spectroscopies, XRD and electron microscopy. For the polypropylene-based composite, the titanium phosphonate fillers synthesized from diethyl octylphosphonate (DEOP) exhibited an average size of 900 nm and appeared well-dispersed. XRD experiments demonstrated the absence of signal corresponding to crystalline layered titanium phosphonate. With polystyrene, two diethyl phosphonate molecules containing aromatic groups were used to obtain composites. The diethyl benzylphosphonate (DEBP) led to the formation of agglomerates of about 490 nm whereas diethyl phenylphosphonate (DEPP) led to the formation of bigger fillers. However, both systems led to the appearance of fillers with a platelet-like morphology. These results confirmed the significant impact of the solvent (here viscous polymer medium) on the growth and morphology of the created objects. Graphical Abstract Highlights Polymer/titanium phosphonates nanocomposites synthesized by a one-step non-hydrolytic sol-gel process into molten polymer. Layered titanium phosphonates obtained in a PS matrix. Possibility to modulate the aspect ratio in a molten polymer medium.

A high-phosphorus-content polyphosphonate (PBDA), containing two phosphorus-based structures: phosphaphenanthrene (DOPO) and phenyl phosphonate groups, was synthesized and used in flame retardant polyethylene terephthalate (PET). Good self-extinguishing property (high UL 94 grade and LOI value), superior flame retardancy (lower heat/smoke release), and high quality retention (high carbon residue) were endowed to PET by PBDA. When 10 wt% PDBA was added, the peak heat release rate (pHRR), total heat release (THR), and total smoke rate (TSR) of PDBA/PET were found to be significantly reduced by 80%, 60.5%, and 21%, respectively, compared to the pure PET, and the LOI value jumped from 20.5% for pure PET to 28.7% with a UL-94 V-0 rating. The flame-retardant mode of action in PET was verified by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), real-time FTIR, and scanning electron microscopy (SEM). Phosphaphenanthrene and phosphonate moieties in PDBA decomposed in sequence during heating, continuously releasing and keeping high-content PO· and PO2· radicals with a quenching effect and simultaneously promoting the formation of viscous crosslinked char layers causing a high barrier effect. PDBA mainly acted in the gas phase but the condensed-phase flame retardant function was also considerable.

Poly(L-lactide) (PLA) is a promising biopolymer for biomedical applications due to its biodegradability and biocompatibility; however, its brittleness restricts its use in fused deposition modeling (FDM). To overcome this limitation, flexible PLA monofilaments with enhanced mechanical performance and printability were developed. In this study, PLA was melt-blended with acetyl triethyl citrate (ATEC, 1.0–5.0 wt%) as a plasticizer and zinc phenyl phosphonate (TMC-200, 0.3 wt%) as a nucleating agent. It was found that the PLA with 3.0 wt% ATEC (PLA/A) exhibited the greatest flexibility, while the addition of TMC-200 further improved tensile strength and ductility. Specifically, the ternary blend of PLA/TMC-200/ATEC (PLA/T/A) exhibited a synergistic effect, achieving superior mechanical properties (tensile strength: 35.0 MPa, elongation at break: 232.0%, compared to 12.1% for pure PLA) and raising the degree of crystallinity (Xc) from 4.7% to 45.0%. Monofilaments (1.70 ± 0.05 mm) fabricated from PLA/T/A exhibited smooth surfaces, balanced mechanical performance, and excellent cytocompatibility (over 99% cell viability in L929 fibroblasts). Moreover, FDM-printed specimens retained enhanced mechanical and thermal performance, demonstrating material stability after processing. Shelf-life testing further confirmed the structural integrity of PLA/T/A monofilament after 8 weeks at 50 °C. Overall, PLA/T/A provides an effective strategy for producing high-performance, medical-grade PLA monofilaments with improved toughness, printability, and biocompatibility, enabling their application in biomedical 3D printing.

Quantum mechanics/molecular mechanics (QM/MM) maturation of an immunoglobulin (Ig) powered by supercomputation delivers novel functionality to this catalytic template and facilitates artificial evolution of biocatalysts. We here employ density functional theory-based (DFT-b) tight binding and funnel metadynamics to advance our earlier QM/MM maturation of A17 Ig-paraoxonase (WTIgP) as a reactibody for organophosphorus toxins. It enables regulation of biocatalytic activity for tyrosine nucleophilic attack on phosphorus. The single amino acid substitution L-Leu47Lys results in 340-fold enhanced reactivity for paraoxon. The computed ground-state complex shows substrate-induced ionization of the nucleophilic L-Tyr37, now H-bonded to L-Lys47, resulting from repositioning of L-Lys47. Multiple antibody structural homologs, selected by phenylphosphonate covalent capture, show contrasting enantioselectivities for a P-chiral phenylphosphonate toxin. That is defined by crystallographic analysis of phenylphosphonylated reaction products for antibodies A5 and WTIgP. DFT-b analysis using QM regions based on these structures identifies transition states for the favored and disfavored reactions with surprising results. This stereoselection analysis is extended by funnel metadynamics to a range ofWTIgP variants whose predicted stereoselectivity is endorsed by experimental analysis. The algorithms used here offer prospects for tailored design of highly evolved, genetically encoded organophosphorus scavengers and for broader functionalities of members of the Ig superfamily, including cell surface-exposed receptors.

The iridium-catalyzed C-H borylation of diethyl phenylphosphonate results in nonselective mono and bisborylation to afford a near statistical mixture of 3-, 3,5- and 4-boryl substituted aryl phosphonates whereas 3-substituted aryl phosphonates undergo highly regioselective C-H borylation to afford the corresponding meta-phosphonate substituted arylboronic esters as the sole product; the resulting boronic esters were used as nucleophilic reagents in a subsequent palladium-catalyzed Suzuki–Miyaura cross-coupling to generate a range of biarylmonophosphonates. Gratifyingly, the Suzuki–Miyaura cross-coupling can be conducted without purifying the boronic ester which greatly simplifies the synthetic procedure.