Silver nanoparticles-decorated polyphosphazene nanotubes: synthesis and applications

Synchronous modification of ZIF-67 with cyclomatrix polyphosphazene coating for efficient flame retardancy and mechanical reinforcement of epoxy resin

Cyclomatrix polyphosphazenes have attracted widespread attention in the field of polymer flame retardancy. Nevertheless, the optimal manifestation of their distinctive structural attributes and flame-retardant properties necessitates a judicious selection of condensation monomers and synergistic templates during the fabrication of polyphosphazene flame retardants. In our previous studies, it was discovered that when ZIF-67 is functionalized with polyphosphazene, the by-product HCl from phosphazene polycondensation causes etching on ZIF-67. Based on this "synchronous etching" effect, a series of hybrid materials comprising cyclomatrix polyphosphazene and ZIF-67, denoted as ZIF-67@PDS (PDS, poly-(cyclotriphosphazene-co-4,4'-diaminodiphenyl sulfone)), ZIF-67@PBS (PBS, poly-(cyclotriphosphazene-co-Bisphenol A)), and ZIF-67@PZS (PZS, poly-(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)), was synthesized utilizing DDS (4,4'-diaminodiphenyl sulfone), BPA (Bisphenol A), and BPS (4,4'-sulfonyldiphenol) monomers as precursors, respectively. Upon the incorporation of 2.0 wt.% of ZIF-67@PDS, ZIF-67@PBS, and ZIF-67@PZS, the flame retardant and mechanical characteristics of EP composites exhibited marked enhancement. The unique structural characteristics of hybrid and the synergistic effects of Co-P-N contribute to the improvement of comprehensive properties. Compared with pure EP, EP/ZIF-67@PZS has the best enhancement effect, and its pHRR, THR, and TSP decreased by 34.0%, 30.0%, and 40.5%, respectively. In terms of mechanical strength, ZIF-67@PZS also increases the flexural strength of EP by 37.42%. Relying on the "synchronous etching" effect, this study explores and verifies the effective combination of ZIF-67 and different types of polyphosphazenes, and obtains a series of ZIF-67-derived cyclomatrix polyphosphazene hybrids with different morphologies and properties in one step. It provides a new idea and strategy for the simultaneous modification of polyphosphazene materials and the preparation of multifunctional flame retardants in the future.

Highly efficient and selective heterogeneous catalytic reduction of 2-nitroaniline by cerium oxide nanocatalyst under microwave irradiation

Efficient nanocatalyst with incredible performance is highly demanding in a heterogeneous catalysis system. Herein, we report the facile fabrication of uniform and highly stable Cerium Oxide nanoparticles (CeO₂ NPs), through chemical precipitation method using sodium hydroxide as reducing agent. The synthesized material is characterized through highly sophisticated techniques including UV-Visible, FT-IR, SEM, AFM, XRD, and Zeta Sizer- Potential to check the particle formation, surface morphology, topography, crystalline nature, size, and surface potential. The heterogeneous catalytic performance of CeO₂ NPs has been accomplished for the reduction of 2-nitroaniline from the aqueous media. The CeO₂ nanocatalyst displayed excellent reusability, while the reduction in several repetitive catalytic cycles against 2-nitroaniline under optimized conditions. The CeO₂ nanocatalyst shows 99.12% efficiency within 60s reaction time under a greener source of microwave radiation.

Phosphazene Cyclomatrix Network-Based Polymer: Chemistry, Synthesis, and Applications

Polyphosphazenes are an inorganic molecular hybrid family with multifunctional properties due to their wide range of organic substitutes. This review intends to propose the basics of the synthetic chemistry of polyphosphazene, describing for researchers outside the field the basic knowledge required to design and prepare polyphosphazenes with desired properties. A special emphasis is placed on recent advances in chemical synthesis, which allow not only the synthesis of polyphosphazenes with controlled molecular weights and polydispersities but also the synthesis of novel branched designs and block copolymers. We also investigated the synthesis of polyphosphazenes using various functional materials. This review aims to assist researchers in synthesizing their specific polyphosphazene material with unique property combinations, with the hope of stimulating further research and even more innovative applications for these highly interesting multifaceted materials.

Morphology-Controlled Synthesis of Polyphosphazene-Based Micro- and Nano-Materials and Their Application as Flame Retardants

Common flame retardants, such as halogen-based materials, are being phased-out owing to their harmful environmental and health effects. We prepared poly-(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) microspheres, nanotubes, capsicum-like nanotubes, and branched nanotubes as flame retardants. An increase in reaction temperature changed the morphology from nanotubes to microspheres. A PZS shape had a positive effect on the flame retardancy of polyethylene terephthalate (PET). The PZS with a capsicum-like nanotube morphology had the best flame retardancy, and the PET limiting oxygen index increased from 25.2% to 34.4%. The flame retardancy capability was followed by PZS microspheres (33.1%), branched nanotubes (32.8%), and nanotubes (32.5%). The capsicum-like nanotubes promote the formation of highly dense and continuous carbon layers, and they release a non-combustible gas (CO2). This study confirms polyphosphazene-based flame retardants as viable and environmentally-friendly alternatives to common flame retardants. It also presents a novel and facile design and synthesis of morphology-controlled nanomaterials with enhanced flame retardant properties.

Fabrication of Bimetallic Cu-Ag Nanoparticle-Decorated Poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) and Its Enhanced Catalytic Activity for the Reduction of 4-Nitrophenol

We reported a study on the preparation of bimetallic Ag-Cu nanoparticles (NPs) impregnated on PZS poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanotubes via a facile and efficient reduction method. Herein, PZS nanotubes consisting of enriched hydroxyl groups are fabricated through an in situ template method, and then, fluctuating the amount ratios of Cu and Ag precursors, bimetallic NPs can be fabricated on readily prepared PZS nanotubes using NaBH₄ as a reductant, which results in a series of bimetallic catalysts having tunable catalytic activity. The characterization investigations of scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy results show that Ag-Cu bimetallic NPs are well-dispersed, ultrasmall in size, and well-anchored on the surface of PZS nanotubes. In addition, to examine the catalytic activity and reusability of these nanocomposites, reduction of 4-nitrophenol to 4-aminophenol is utilized as a prototype reaction. The optimized Ag-Cu NPs with a copper ratio of 0.3% are well-stabilized by the organic-inorganic poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanotubes. The obtained results show that bimetallic NPs have remarkably higher catalytic ability than that of their monometallic counterparts with maximum catalytic activity. These results are even better than those of noble metal-based bimetallic catalysts and pave the avenue to utilize the polyphosphazene polymer as a substrate material for highly effective bimetallic catalysts.

Preparation and Antimicrobial Activity of Antibacterial Silver-Loaded Polyphosphazene Microspheres

Poly(cyclotriphosphazene-co-4,4'-diaminodiphenyl ether) (PPO) microspheres were prepared via a precipitation polymerization method, using hexachlorocyclotriphosphazene (HCCP) and 4,4'-diaminodiphenyl ether (ODA) as monomers. Silver-loaded PPO (PPOA) microspheres were generated by the in situ loading of silver nanoparticles onto the surface by Ag⁺ reduction. Our results showed that PPOA microspheres were successfully prepared with a relatively uniform distribution of silver nanoparticles on microsphere surfaces. PPOA microspheres had good thermal stability and excellent antibacterial activity towards Escherichia coli and Staphylococcus aureus. Furthermore, PPOA microspheres exhibited lower cytotoxicity when compared to citrate-modified silver nanoparticles (c-Ag), and good sustained release properties. Our data indicated that polyphosphazene-based PPOA microspheres are promising antibacterial agents in the biological materials field.

Synthesis of a Reactive Template-Induced Core-Shell PZS@ZIF-67 Composite Microspheres and Its Application in Epoxy Composites

Developing superior properties of epoxy resin composites with high fire resistance, light smoke, and low toxicity has been the focus of the research in the flame-retardant field. In particular, it is essential to decrease the emissions of toxic gases and smoke particles generated during the thermal decomposition of epoxy resin (EP) to satisfy the industrial requirements for environmental protection and safety. Consequently, the PZS@ZIF-67 composite was designed and synthesized by employing the hydroxyl group-containing polyphosphazene (poly(cyclotriphosphazene-co-4,4'-dihydroxydiphenylsulfone), PZS) as both the interfacial compatibility and an in situ template and the ZIF-67 nanocrystal as a nanoscale coating and flame-retardant cooperative. ZIF-67 nanocrystal with multidimensional nanostructures was uniformly wrapped on the surface of PZS microspheres. Subsequently, the acquired PZS@ZIF-67 composite was incorporated into the epoxy resin to prepare composite samples for the study of their fire safety, toxicity suppression, and mechanical performance. Herein, the EP/5% PZS@ZIF-67 passed the V-0 rating in a UL-94 test with a 31.9% limit oxygen index value. More precisely, it is endowed with a decline of 51.08%, 28.26%, and 37.87% of the peak heat release rate, the total heat release, and the total smoke production, respectively. In addition, the unique structure of PZS@ZIF-67 microsphere presented a slight impact on the mechanical properties of EP composites at low loading. The PZS@ZIF-67 possible flame-retardant mechanism was speculated based on the analysis of the condensed phase and the gas phase of EP composites.

Effective Poly (Cyclotriphosphazene-Co-4,4'-Sulfonyldiphenol)@rGO Sheets for Tetracycline Adsorption: Fabrication, Characterization, Adsorption Kinetics and Thermodynamics

The development of excellent drug adsorbents and clarifying the interaction mechanisms between adsorbents and adsorbates are greatly desired for a clean environment. Herein, we report that a reduced graphene oxide modified sheeted polyphosphazene (rGO/poly (cyclotriphosphazene-co-4,4'-sulfonyldiphenol)) defined as PZS on rGO was used to remove the tetracycline (TC) drug from an aqueous solution. Compared to PZS microspheres, the adsorption capacity of sheeted PZS@rGO exhibited a high adsorption capacity of 496 mg/g. The adsorption equilibrium data well obeyed the Langmuir isotherm model, and the kinetics isotherm was fitted to the pseudo-second-order model. Thermodynamic analysis showed that the adsorption of TC was an exothermic, spontaneous process. Furthermore, we highlighted the importance of the surface modification of PZS by the introduction of rGO, which tremendously increased the surface area necessary for high adsorption. Along with high surface area, electrostatic attractions, H-bonding, π-π stacking and Lewis acid-base interactions were involved in the high adsorption capacity of PZS@rGO. Furthermore, we also proposed the mechanism of TC adsorption via PZS@rGO.

Construction of silver nanoparticles by the triple helical polysaccharide from black fungus and the antibacterial activities

Size controllable silver nanoparticles (AgNPs) were synthesized in situ on the polysaccharides-based nanotubes, which were formed by the triple-helix polysaccharide extracted from black fungus (AF1). The results of transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) proved that AgNPs with the size from 10-25 nm were uniformly dispersed on the surface of AF1 dendritic nanotubes without affecting their tubular morphology. Moreover, due to the tubular structure, the loaded silver content of the composites (AgNPs and AF1 nanotube, AF1-Ag) could reach about 50% by thermogravimetric analysis (TG) evaluation. Thus, the smaller size of AgNPs and higher silver loading content suggest that the composites could be applied in the biomedical field. The antibacterial properties of AF1-Ag were evaluated as an example in the present work. As expected, the culture medium contained a few of AF1-Ag (10% ω%, c = 50 μg/mL) exhibited obvious antibacterial properties, and the effect of bacteriostasis increased with the increase of the amount of supported silver content. Taken together, the AF1-Ag with good antibacterial activity and good stability has the potential to be applied in the antibacterial field.

Electrostatic Interaction-Controlled Formation of Pickering Emulsion for Continuous Flow Catalysis

Although noble metal or non-noble metal-catalyzed reactions are widely used, it is still difficult to apply these reactions in the large-scale synthesis of chemicals because most of the reactions are carried out by the inefficient batch reaction strategy. Herein, Pickering emulsion-based continuous flow catalysis was utilized to address this problem. Cellulose nanofibers with aldehyde groups (ACNF) were generated through oxidizing C2 and C3 hydroxyl groups of cellulose nanofibers into aldehyde groups by NaIO₄, followed by in situ depositing Ag nanoparticles on ACNF to produce Ag-decorated ACNF (ACNF@Ag) via a facile aldehyde-induced reduction method. ACNF@Ag with ∼2 wt % Ag (ACNF@Ag2) has been used to prepare the Pickering emulsion by controlling the electrostatic interaction between ACNF@Ag2 and the oil-water interface via adjusting the pH. It was found that the Pickering emulsion could be generated at a pH around 3.29 and was determined to be the oil-in-water emulsion. The reduction of organic molecules (4-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO)) was selected as a model reaction to test the reliability of the Pickering emulsion in continuous flow catalysis, which demonstrated very high conversion rates for 4-NP (>98%, 50 h), MB (>99%, 30 h), and MO (>96%, 40 h).

The synthesis of conjugated microporous polymers via nucleophilic substitution of hydroquinone with cyanuric chloride and hexachlorocyclotriphosphazene for sensing to 2,4-dinitrophenol and 2,4,6-trinitrophenol

Hydroquinone is an electron-rich connector similar in structure to DNP and TNP. Two hydroquinone-based conjugated microporous polymers have excellent fluorescence sensing performance for DNP and TNP, respectively.

Recent advances in the supramolecular assembly of cyclophosphazene derivatives

There is still room for improvement in supramolecular systems based on cyclophosphazene derivatives and their potential applications.

Charge Redistribution Caused by S,P Synergistically Active Ru Endows an Ultrahigh Hydrogen Evolution Activity of S-Doped RuP Embedded in N,P,S-Doped Carbon

Water splitting for production of hydrogen as a clean energy alternative to fossil fuel has received much attention, but it is still a tough challenge to synthesize electrocatalysts with controllable bonding and charge distribution. In this work, ultrafine S-doped RuP nanoparticles homogeneously embedded in a N, P, and S-codoped carbon sheet (S-RuP@NPSC) is synthesized by pyrolysis of poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) as the source of C/N/S/P. The bondings between Ru and N, P, S in PZS are regulated to synthesize RuS2 (800 °C) and S-RuP (900 °C) by different calcination temperatures. The S-RuP@NPSC with low Ru loading of 0.8 wt% with abundant active catalytic sites possesses high utilization of Ru, the mass catalytic activity is 22.88 times than 20 wt% Pt/C with the overpotential of 250 mV. Density functional theory calculation confirms that the surface Ru (-0.18 eV) and P (0.05 eV) are catalytic active sites for the hydrogen evolution reaction (HER), and the according charge redistribution of Ru is regulated by S and P with reverse electronegativity and electron-donor property to induce a synergistically enhanced reactivity toward the HER. This work provides a rational method to regulate the bonding and charge distribution of Ru-based electrocatalysts by reacting macromolecules with multielement of C/N/S/P with Ru.

(Amino)cyclophosphazenes as Multisite Ligands for the Synthesis of Antitumoral and Antibacterial Silver(I) Complexes

The reactivity of the multisite (amino)cyclotriphosphazene ligands, [N₃P₃(NHCy)₆] and [N₃P₃(NHCy)₃(NMe₂)₃], has been explored in order to obtain silver(I) metallophosphazene complexes. Two series of cationic silver(I) metallophosphazenes were obtained and characterized: [N₃P₃(NHCy)₆{AgL}_n](TfO)_n [n = 2, L = PPh₃ (2), PPh₂Me (4); n = 3, L = PPh₃ (3), PPh₂Me (5), TPA (TPA = 1,3,5-triaza-7-phosphaadamantane, 6)] and nongem-trans-[N₃P₃(NHCy)₃(NMe₂)₃{AgL}_n](TfO)_n [n = 2, L = PPh₃ (7), PPh₂Me (9); n = 3, L = PPh₃ (8), PPh₂Me (10)]. 5, 7, and 9 have also been characterized by single-crystal X-ray diffraction, thereby allowing key bonding information to be obtained. Compounds 2-6, 9, and 10 were screened for in vitro cytotoxic activity against two tumor human cell lines, MCF7 (breast adenocarcinoma) and HepG2 (hepatocellular carcinoma), and for antimicrobial activity against five bacterial species including Gram-positive, Gram-negative, and Mycobacteria strains. Both the IC₅₀ and MIC values revealed excellent biological activity for these metal complexes, compared with their precursors and cisplatin and also AgNO₃ and silver sulfadiazine, respectively. Both IC₅₀ and MIC values are among the lowest values found for any silver derivatives against the cell lines and bacterial strains used in this work. The structure-activity relationships were clear. The most cytotoxic and antimicrobial derivatives were those with the triphenylphosphane and [N₃P₃(NHCy)₆] ligands. A significant improvement in the activity was also observed upon a rise in the number of silver atoms linked to the phosphazene ring.

Melamine-containing polyphosphazene wrapped ammonium polyphosphate: A novel multifunctional organic-inorganic hybrid flame retardant

To achieve superior fire safety epoxy resins (EP), a novel multifunctional organic-inorganic hybrid, melamine-containing polyphosphazene wrapped ammonium polyphosphate (PZMA@APP) with rich amino groups was prepared and used as an efficient flame retardant. Thanks to the cross-linked polyphosphazene part, PZMA@APP exhibited high flame retardant efficiency and smoke suppression to the EP composites. Thermogravimetric analysis indicated that PZMA@APP significantly enhanced the thermal stability of EP composites. The obtained sample passed UL-94 V-0 rating with 10.0wt% addition of PZMA@APP. Notably, inclusion of incorporating PZMA@APP leads to significantly decrease on fire hazards of EP, for instance, bring about a 75.6% maximum decrease in peak heat release rate and 65.9% maximum reduction in total heat release, accompanied with lower smoke production rate and higher graphitized char layer. With regards to mechanical property, the glass transition temperature of EP/PZMA@APP10.0 was as high as 184.5°C. In particular, the addition of PZMA@APP did not worsen the mechanical properties, compared to pure APP. It was confirmed that the participation of melamine-containing polyphosphazene could significantly enhance the quality of char layer and thereby resulting the higher flame retardant efficiency of PZMA@APP.

In Situ Synthesis of Silver Nanoparticles on the Polyelectrolyte-Coated Sericin/PVA Film for Enhanced Antibacterial Application

To develop silk sericin (SS) as a potential antibacterial biomaterial, a novel composite of polyelectrolyte multilayers (PEMs) coated sericin/poly(vinyl alcohol) (SS/PVA) film modified with silver nanoparticles (AgNPs) has been developed using a layer-by-layer assembly technique and ultraviolet-assisted AgNPs synthesis method. Ag ions were enriched by PEMs via the electrostatic attraction between Ag ions and PEMs, and then reduced to AgNPs in situ with the assistance of ultraviolet irradiation. PEMs facilitated the high-density growth of AgNPs and protected the synthesized AgNPs due to the formation of a 3D matrix, and thus endowed SS/PVA film with highly effective and durable antibacterial activity. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, Fourier transfer infrared spectroscopy, water contact angle, mechanical property and thermogravimetric analysis were applied to characterize SS/PVA, PEMs-SS/PVA and AgNPs-PEMs-SS/PVA films, respectively. AgNPs-PEMs-SS/PVA film has exhibited good mechanical performance, hydrophilicity, water absorption capability as well as excellent and durable antibacterial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and good stability and degradability. This study has developed a simple method to design and prepare AgNPs-PEMs-SS/PVA film for potential antibacterial application.

Constructing 3D Polyphosphazene Nanotube@Mesoporous Silica@Bimetallic Phosphide Ternary Nanostructures via Layer-by-Layer Method: Synthesis and Applications

A novel ternary nanostructure polyphosphazene nanotube (PZS)@ mesoporous silica (M-SiO₂)@bimetallic phosphide (CoCuP) was facilely fabricated, using PZS as the template, where large amount of cetyltrimethylammonium bromide molecules were anchored to PZS via a similar layer-by-layer assembly strategy, and then uniform M-SiO₂ shells can be formed successfully by Hyeon's coating method. Subsequently, the three-dimensional (3D) nanostructure on the basis of bimetallic phosphide (CoCuP) interconnected with PZS@M-SiO₂ was synthesized via a convenient, mild hydrothermal route. It is noted that incorporating well-designed PZS@M-SiO₂@CoCuP led to significant decrease on fire hazard of thermoplastic polyurethane (TPU), that is, 58.2% and 19.4% reductions in peak heat release rate and total heat release, respectively, as well as lower toxic hydrogen cyanide and carbon monoxide yield accompanied by higher graphitized char layer. In the case of TPU/PZS@M-SiO₂@CoCuP system, the storage modulus at -97 °C was dramatically improved by 62.6%, and glass transition temperature was shifted to higher value, compared to those of pure TPU. The enhanced fire safety and mechanical property for TPU composites can be ascribed to tripartite cooperative effect from respective parts (CoCuP and M-SiO₂) plus the PZS.

Flame-retardant-wrapped polyphosphazene nanotubes: A novel strategy for enhancing the flame retardancy and smoke toxicity suppression of epoxy resins

The structure of polyphosphazene nanotubes (PZS) is similar to that of carbon nanotubes (CNTs) before modification. For applications of CNTs in polymer composites, surface wrapping is an economically attractive route to achieve functionalized nanotubes. Based on this idea, functionalized polyphosphazene nanotubes (FR@PZS) wrapped with a cross-linked DOPO-based flame retardant (FR) were synthesized via one-step strategy and well characterized. Then, the obtained FR@PZS was introduced into epoxy resin (EP) to investigate flame retardancy and smoke toxicity suppression performance. Thermogravimetric analysis indicated that FR@PZS significantly enhanced the thermal stability of EP composites. Cone calorimeter results revealed that incorporation of FR@PZS obviously improved flame retardant performance of EP, for example, 46.0% decrease in peak heat release rate and 27.1% reduction in total heat release were observed in the case of epoxy composite with 3wt% FR@PZS. The evolution of toxic CO and other volatile products from the EP decomposition was significantly suppressed after the introduction of FR@PZS, Therefore, the smoke toxicity associates with burning EP was reduced. The presence of both PZS and a DOPO-based flame retardant was probably responsible for this substantial diminishment of fire hazard.

Fabrication of Sesame Sticks-like Silver Nanoparticles/Polystyrene Hybridnanotubes and Their Catalytic Effects

A novel and efficient catalyst is one of the goals in the material field, and the involvement of nanoscience and technology has brought new vigor to the development of catalyst. This research aimed to develop a simple two-step route to fabricate Fe3O4@PS/PDA-Ag hybridnanotubes with size-controllable and highly dispersed silver nanoparticles (NPs). First, Fe3O4@PS nanotubes of a sound mechanical property were prepared using polystyrene (PS)/toluene solution containing highly dispersed oleic acid modified Fe3O4 particles in a commercial AAO template. Next, the facile technique was used to form in situ silver NPs on the surface of magnetic PS (Fe3O4@PS) nanotubes through dopamine coating. The catalytic effects of the prepared Fe3O4@PS/PDA-Ag hybridnanotubes with highly dispersed AgNPs were characterized using a range of analytical methods, including transmission electron microscopy, thermogravimetric analysis, UV-Visible spectroscopy, and X-ray diffraction. It was found that such prepared Fe3O4@PS/PDA-Ag hybridnanotubes had a large specific surface area. They possessed excellent activities in catalyzing the reduction of 4-nitrophenol (4-NP) by NaBH4 in the aqueous phase. Furthermore, they were readily separated from fluid and retrieved by an external magnet. Their catalyst activity and recyclability demonstrated that this approach we proposed had the potential to become a new idea and route for catalytic platform.

Liquid Marbles Stabilized by Fluorine-Bearing Cyclomatrix Polyphosphazene Particles and Their Application as High-Efficiency Miniature Reactors

Increasing attention has been paid to fabricate multifunctional stabilizers of liquid marbles for expanding their application. Here, a kind of hydrophobic cyclomatrix polyphosphazene particles (PZAF) were facilely prepared using a one-step precipitation polycondensation of hexachlorocyclotriphosphazene and 4,4'-(hexafluoroisopropylidene)diphenol, and their ability to stabilize liquid marbles was first investigated. The Ag nanoparticle-decorated PZAF particles (Ag/PZAF) were then fabricated by an in situ reduction of silver nitrate onto PZAF particles and used to construct catalytic liquid marbles. The results revealed that the reduction of methylene blue (MB) in aqueous solution by sodium borohydride could be highly efficiently catalyzed in the catalytic liquid marbles, even with a large volume. An excellent cycle use performance of the catalytic liquid marbles without losing catalytic efficiency was also present. The high catalytic activity is mainly attributed to the uniform immobilization of Ag nanoparticles onto PZAF particles and the adsorption behavior of PZAF particles toward MB, which may play an effect on allowing high catalytic surface area and effective accelerating the mass transfer of MB to the Ag catalytic active sites, respectively. Therefore, the combination of Ag nanoparticles with PZAF particles has been demonstrated clearly to be a facile and effective strategy to obtain the functional stabilizer for preparing the catalytic liquid marbles as promising miniature reactors used in heterogeneous catalytic reactions.

Polyphosphazenes for the Stille reaction: a new type of recyclable stannyl reagent

A random phosphazene copolymer {[N = P((CH2)7-Br)Ph]0.5[N = PMePh]0.5}n (2) and a block copolyphosphazene {[N = P((CH2)7-Br)Ph]0.5[N = PMePh]0.5}45-b-[N = P(O2C12H8)]55 (5), having a branch with two randomly distributed units, have been synthesized and used as precursors for the stannyl derivatives {[N = P((CH2)7-SnBu2An)Ph]0.5[N = PMePh]0.5}n (3) and {[N = P((CH2)7-SnBu2An)Ph]0.5[N = PMePh]0.5}45-b-[N = P(O2C12H8)]55 (6, An = p-MeOC6H4). Polymers 3 and 6 were tested as recyclable tin reagents in the Stille cross-coupling reaction with ArI, using various Pd catalysts and different experimental conditions. Polymer 6 can be recycled without a significant release of tin, but its efficiency decreased after three consecutive cycles. This effect was explained by studying the self-assembly of the polymer under the same conditions used for the catalytic experiments, which evidenced the progressive coalescence of the polymeric vesicles (polymersomes) leading to stable and bigger core-shell aggregates by the attraction of the [N = P(O2C12H8)] rich membranes, thus decreasing the accessibility of the tin active centers.

Core–shell structured nanocomposites Ag@CeO2 as catalysts for hydrogenation of 4-nitrophenol and 2-nitroaniline

A combination of the redox reaction and reverse micelle technique was used for synthesis of core–shell Ag@CeO₂ nanocomposites, which shows superior catalytic activity and durability for the hydrogenation of 4-NP and 2-NA with NaBH₄, respectively.

POSS-functionalized polyphosphazene nanotube: preparation and effective reinforcement on UV-curable epoxy acrylate nanocomposite coatings

This study presents an efficient method of preparing functionalized poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotube reinforced UV-curable materials.

A strategy for the synthesis of cyclomatrix-polyphosphazene nanoparticles from non-aromatic monomers

Cyclomatrix-polyphosphazenes (C-PPZs) are a new class of nanomaterials that have attracted significant interest owing to their unique inorganic–organic hybrid structure and tunable properties.

Fabrication of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) nanotubes decorated with Ag–Au bimetallic nanoparticles with enhanced catalytic activity for the reduction of 4-nitrophenol

Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) nanotubes are facilely prepared and employed as a support to deposit Ag–Au bimetallic nanoparticles directly, which show superior catalytic performance.

Nanosilver as a new generation of silver catalysts in organic transformations for efficient synthesis of fine chemicals

Silver nanoparticles catalysis has been of great interest in organic synthesis and has expanded rapidly in the past ten years because of nanosilver catalysts' unique reactivity and selectivity, stability, as well as recyclability in catalytic reactions.

Preparation of UV-curable functionalized phosphazene-containing nanotube/polyurethane acrylate nanocomposite coatings with enhanced thermal and mechanical properties

Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes with active hydroxyl groups were fabricated via an in situ template method under mild conditions, and then modified by acryloyl chloride to obtain the acryloyl-group functionalized PZS (f-PZS) nanotubes.

Hollow polyphosphazene microspheres with cross-linked chemical structure: synthesis, formation mechanism and applications

Hollow polyphosphazene microspheres with highly cross-linked chemical structures were prepared by a template-induced assembly mechanism. The hollow microspheres display good stability towards Au nanoparticles.

Adsorption of methylene blue onto poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanotubes: kinetics, isotherm and thermodynamics analysis

Poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) nanotubes, an excellent adsorbent, were successfully synthesized by an in situ template method and used for the removal of methylene blue (MB) from aqueous solution. The morphology and structures of as-synthesized PZS nanotubes were characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy and N2 adsorption/desorption isotherms. The effects of temperature, concentration, pH and contact time on MB adsorption were studied. It was favorable for adsorption under the condition of basic and high temperature. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit adsorption data in the kinetic studies. And results showed that the adsorption kinetics were more accurately described by the pseudo-second-order model. The equilibrium isotherms were conducted using Freundlich and Langmuir models. It has been demonstrated that the better agreement was Langmuir isotherm with correlation coefficient of 0.9933, equilibrium absorption capacity of 69.16mg/g and the corresponding contact time of 15min. Thermodynamic analyses showed that MB adsorption onto the PZS nanotubes was endothermic and spontaneous and it was also a physisorption process.

Silica/ultrasmall Ag composite microspheres: facile synthesis, characterization and antibacterial and catalytic performance

Uniform silica/ultrasmall silver composite microspheres have been successfully prepared from silica microspheres and [Ag(NH₃)₂]⁺via a hydrothermal process. The as-prepared silica/Ag microspheres exhibit an excellent antibacterial performance towards E. coli.