Synthesis and characterization of new biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups

Two novel biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups were synthesized via the macromolecular substitution reactions of poly(dichlorophosphazene) with the sodium salt of lactic acid ester and sodium methoxyethoxyethoxide.Their structures were confirmed by ^(31)p NMR,~1H NMR,^(13)C NMR,IR,DSC,and elemental analysis.The lower critical solution temperature(LCST) behavior in water and in vitro degradation property of the polymers was investigated.The...

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

A New Approach to C60-Containing Polyphosphazenes by Polymerization of Phosphonitrile Chloride Trimer in the Presence of C60

A novel synthetic strategy was developed to prepare polyphosphazenes containing C60 moieties. Thus, the phosphonitrile chloride trimer underwent thermal ring-opening polymerization （ROP） in the presence of C60 molecules to yield the reactive macromolecular intermediate, C60-containing poly（dichlorophosphazene）. And then, the other groups could be linked to the phosphazene backbone by nucleophilic substitution reaction of the chlorine atoms in this intermediate to produce a series of C60-containing polyphosphazene. The polymer exhibits good solubility in common organic solvents and is thermally stable.

Water-soluble CdSe/ZnS quantum dots passivated by poly(glycino amino acid) phosphazenes

Poly(organophosphazenes) have potential applications in making water-soluble and biocompatible quantum dots (QDs) due to their wide variety of properties. The CdSe QDs of green emission and the core-shell CdSe/ZnS QDs of red emission were prepared. Subsequently the trioctylphosphine oxide-stabilized CdSe/ZnS QDs were transferred from chloroform into water through a ligand exchange process with poly(glycino amino acid)phosphazenes, which can be obtained from the saponification of poly (glycino amino ester)phosphazenes at room temperature. The resulting QDs-polymer nanocomposite particles can form colloidally stable suspensions in water and exhibit good photostability.

Flame Retardancy and Thermal Property of Poly (ethylene terephthalate)/Modified Cyclotriphosphazene Composites

In this study,hexachlorocyclotriphosphazene( HCCP)modified by boric acid and 3-aminopropyltriethoxysilane( KH-550)in solvent diglyme( FR-HCCP) was used as the flame retardant for poly( ethylene terephthalate)( PET) composites. The flame retardancy and thermal property of pure PET and flame-retarded PET composites were mainly investigated. The flame retardancy was investigated by limited oxygen index( LOI) and UL-94 vertical burning test. The results showed that the composites could achieved an increased UL-94 V-0 rating and LOI value 30. 2, when the content of FR-HCCP was just 1%. The pyrolysis-gas chromatography-mass spectrometry( Py-GC / MS) study demonstrated that introducing FR-HCCP into PET would prevent the polymer pyrolysis during heating. TGA analysis showed that the addition of FR-HCCP could improve the char formation of the system. Roman spectra showed the order degree of residue was increasing by adding the additive. The morphology and the chemical structure of the charred residue were detected by SEMand FTIR,respectively. Results demonstrated that a good barrier was formed by the char of the composite,which protected the inside of the composite during burning.

Preparation and evaluation of crosslinked sulfonated polyphosphazene with poly(aryloxy cyclotriphosphazene) for proton exchange membrane

Several crosslinked proton exchange membranes with high proton conductivities and low methanol permeability coefficients were prepared, based on the sulfonated poly[(4-fluorophenoxy)(phenoxy)] phosphazene(SPFPP) and newly synthesized water soluble sulfonated poly(cyclophosphazene)(SPCP) containing clustered flexible pendant sulfonic acids. The structure of SPCP was characterized by fourier transform infrared spectroscopy(FTIR) and ~1H NMR spectra. The membranes showed moderate proton conductivities and much lower methanol permeability coefficients when compared to Nafion 117. Transmission electron microscopy(TEM) results indicated the well-defined phase separation between the locally and densely sulfonated units and hydrophobic units, which induced efficient proton conduction. In comparison with SPFPP membrane, the proton conductivities, oxidative stabilities and mechanical properties of crosslinked membranes remarkably were improved. The selectivity values of all the crosslinked membranes were also much higher than that of Nafion 117(0.74×10~5S· s/cm~3). These results suggested that the c SPFPP/SPCP membranes were promising candidate materials for proton exchange membrane in direct methanol fuel cells.

Synthesis and Structural Characterization of a Polyphosphazeneas Photoconductivc Material

The synthesis of a novel polyorganophosphazene that contains charge-transporting agent as side chains for photoconductive application is reported. Structural characterization for the high polymer was presented by 1H-NMR, infrared spectrosocopy, gel permeation chromatography (GPC).

Amphiphilic Polyphosphazene with Poly(ethylene oxide) Side Chains Prepared through the Decker-Forster Reaction

Poly （4- methylphenoxyphosphnzene ） -graft-poly （ ethylene oxide ） （ PPZ-g- PEO ）, a novel amphiphilie grafting polymer was prepared via the Decker-Forster reaction. It is found that the graft efficiency increased with extension of reaction time. Low molecular weight of poly （ ethylene oxide ） favored the grafting reaction. The grafted polymer has two different glass transition temperatures（ Tg） with those of pure poly（ 4-methyl- phenoxy-phopsphazene ） and PEO. The emulsifying ability of grafted polymer was studied with benzene-water mixtare. The emulsifying volumes increased with the decreasing of PEO＇ s molecular weight. The contact angle of film forming from grafted polymer decreased after introduction of PEO grafting chain.

Synthesis and Nonlinear Optical Property of a Polyphosphazene with High Glass Transition Temperature

A new polyphosphazene containing binaphtholyl and indole azo chromophores as side chains with high glass transition temperature ( Tg ) was synthesized by a post-functional method. The polymer was well characterized. Its Tg was tested to be 168℃, and the poled film of P2 reveals a resonant d33 value of 20 pm/V by second harmonic generation ( SHG ) measurements.

Conformational Chirality of the Biphenyl Groups Induced by the Aggregation of Poly {bis[4-(4＇-(S)-2-methylbutoxy)- Biphenoxy] Phosphazene}

Poly{bis[4-（4＇-（S）-2-methylbutoxy）biphenyloxy]phosphazene}（PP-C） was designed and successfully synthesized, and then characterized by means of FT-IR spectroscopy, ~1H- and ^（31）P-NMR, GPC spectroscopy, wide angle X-ray diffraction and differential scanning calorimetry. The results indicated that for PP-C, the M_w is 2.18×10~5 and the PDI is 1.96. PP-C was a kind of crystallized polymer with a crystallizing point of -2.0 ℃ and a melting point of 28 ℃. The conformational chirality of the PP-C molecules was studied using circular dichroism spectrum. It was found that in dilute THF solution, the biphenyl groups in the PP-C molecules twisted randomly. However, when the PP-C formed aggregates, the biphenyl groups tended to twist single-handedly, which was controlled by the adjacent chiral alkoxy groups.

Nano-silver-modified polyphosphazene nanoparticles with different morphologies:Design,synthesis,and evaluation of antibacterial activity

Drug-resistant bacteria present a severe threat to public health,emphasizing the importance of developing broad-spectrum antibacterial agents that are free from drug resistance.Among silver-based antibacterial agents,nano-silver has been found to exhibit the most promising and comprehensive performance.The exploration of the antibacterial capacity and morphological changes of silver nanoparticles(AgNPs)could offer a starting point for the development of safe and efficient antibacterial agents.In this study,three types of nano-silver-modified polyphosphazene(PRV)nanoparticles with different morphologies were synthesized using precipitation polymerization.These nanoparticles were characterized using various techniques,including Fourier-transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and thermogravimetric analysis(TGA).The antibacterial activity of these nanoparticles against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)was assessed using minimum inhibitory concentration(MiC)/minimum bactericidal concentration(MBC)tests and inverted fluorescence microscopy.Our results revealed that the antibacterial activity of silver nanoparticles can vary significantly depending on their immobilized form.Ag@PRV Strawberry-like nanoparticles(NPs)exhibited higher antibacterial activity compared to Ag@PRV Yolk-Shell NPs and Ag@PRV Cable-like nanofibers(NFs).Notably,all three types of synthesized nanoparticles demonstrated a stronger bactericidal effect on Gram-positive bacteria than Gram-negative bacteria.Live/dead bacterial staining and scanning electron microscopy demonstrated that silver can kill bacteria by altering the permeability of their cell membranes.These findings offer valuable insights for designing and practically applying new silver-based antibacterial agents in the future.

Synthesis and Characterization of Sulfonated Polyphosphazene-graft-Polystyrene Copolymers for Proton Exchange Membranes

A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） copolymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.

Synthesis of biodegradable poly (methylparaben/glycine ethyl ester) phosphazene and further research of its degradation in vitro

Polydichlorophosphazene(PDCP)was synthesized from PCl5 and NH4Cl via a one-pot approach,and then further reacted with glycine ethyl ester and methylparaben via a two-step nucleophilic substitution approach to give poly(methylparaben/glycine ethyl ester)phosphazene(PMGP),which was a kind of mix-substituted biodegradable polymer.NMR and FT-IR were used to characterize its structure.A series of experiments were conducted to study the effects of the ratio of methylparaben to glycine ethyl ester and the experimental conditions to the degradability of PMGP samples.The degradability of PMGP can be adjusted by altering the ratio of methylparaben to glycine ethyl ester easily.

Synthesis of magnetic polyphosphazene-Ag composite particles as surface enhanced Raman spectroscopy substrates for the detection of melamine

Magnetic polyphosphazene(MPZS) particles coated by Ag nanoparticles(MPZS-Ag) have been developed as surface enhanced Raman spectroscopy(SERS) substrates for sensitive detection of melamine in aqueous solutions and milk samples.5,5’-Dithiobis-(2-nitrobenzoic acid)(DTNB) was used as model analyte to test the SERS activity of the MPZS-Ag particles.The prepared MPZS-Ag particles possess both magnetic responsiveness and excellent SERS properties.SERS detection of different concentrations of melamine aqueous solutions and spiked milk samples were performed by the MPZS-Ag particles.The limit of detection(LOD) of the melamine in aqueous solutions was 10^-7 mol/L(0.0126 mg/L) and 0.6 mg/L in real milk samples using the MPZS-Ag particles as SERS substrates.The LOD of the melamine are much lower than the safety values of Food and Drug Administration and Codex Alimentarius Commission.These results indicate that the MPZS-Ag particles have promising application prospect for SERS analysis in food safety fields.

Composite Polyphosphazene Membranes Doped with Phosphotungstic Acid and Silica

Poly（bis（phenoxy）phosphazene） （SPBPP）/phosphotungstic acid （PWA）/silica composite membranes for fuel cells were prepared. The composite membranes were characterized by using FTIR, TGA and SEM techniquies. Incorporation of PWA particles and silica particles into the SPBPP polymer matrix and a specific interaction between them were confirmed by FTIR spectra. TGA results showed that the composite membranes had high thermal stability. Homogeneous distribution of PWA and silica particles within the SPBPP matrix was verified by SEM micrographs. The doped membranes showed increased water uptake and proton conductivity.

Synthesis and characterization of a new organic-inorganic hybrid polyphosphazene polymer

A new organic-inorganic hybrid polyphosphazene polymer was synthesized via sequential nucleophilic substitution using allylamine and phenol. The polymer was characterized by FTIR, 1H-NMR, and 31P-NMR spectra. The thermal properties were studied by DSC and TGA. It was found that the polymer has good thermal stability. Char yields of the polymer reaches to 48.6% at 800°C. The high char yield makes it possible in theory for the polymer to be used as flame retardant. By cross linking, the thermal stability of the polymer could be improved further.

Synthesis of Polyphosphazene with Pendent Perfluorobutylsulfonylimide Group

A new polyphosphazene with perfluorobutylsulfonylimide as a pendent group has been prepared. The structure of the polymer and its properties were characterized by 1^H NMR, 19^F NMR, IR spectra, gel permeation chromatography, and thermogravimetric analysis.

On the understanding of dielectric elastomer and its application for all-soft artificial heart

Although dielectric elastomer(DE)with substantial actuated strain(AS)has been reported 20 years ago,its scientific understanding remains unclear.The most accepted theory of DE,which is proposed in 2000,holds the view that AS of DE is induced by the Maxwell stress.According to this theory,materials have similar ratios of permittivity and Young’s modulus should have similar AS,while the experimental results are on contrary to this theory,and the experimental AS has no relationship with ideal AS.Here,a new dipole-conformation-actuated strain cross-scale model is proposed,which can be generally applied to explain the AS of DE without pre-strain.According to this model,several characteristics of an ideal DE are listed in this work and a new DE based on polyphosphazene(PPZ)is synthesized.The AS of PPZ can reach 84%without any pre-strain.At last,a PPZ-based all soft artificial heart(ASAH)is built,which works in the similar way with natural myocardium,indicating that this material has great application potential and possibility in the construction of an ASAH for heart failure(HF)patients.

Inhibition of bacterial adhesion and biofilm formation by a textured fluorinated alkoxyphosphazene surface

The utilization of biomaterials in implanted blood-contacting medical devices often induces a persistent problem of microbial infection,which results from bacterial adhesion and biofilm formation on the surface of biomaterials.In this research,we developed new fluorinated alkoxyphosphazene materials,specifically poly[bis(octafluoropentoxy)phosphazene](OFP)and crosslinkable OFP(X–OFP),with improved mechanical properties,and further modified the surface topography with ordered pillars to improve the antibacterial properties.Three X–OFP materials,X–OFP3.3,X–OFP8.1,X–OFP13.6,with different crosslinking densities were synthesized,and textured films with patterns of 500/500/600 nm(diameter/spacing/height)were fabricated via a two stage soft lithography molding process.Experiments with 3 bacterial strains:Staphylococcal epidermidis,Staphylococcal aureus,and Pseudomonas aeruginosa showed that bacterial adhesion coefficients were significantly lower on OFP and X–OFP smooth surfaces than on the polyurethane biomaterial,and surface texturing further reduced bacterial adhesion due to the reduction in accessible surface contact area.Furthermore the anti-bacterial adhesion effect shows a positive relationship with the crosslinking degree.Biofilm formation on the substrates was examined using a CDC biofilm reactor for 7 days and no biofilm formation was observed on textured X–OFP biomaterials.The results suggested that the combination of fluorocarbon chemistry and submicron topography modification in textured X–OFP materials may provide a practical approach to improve the biocompatibility of current biomaterials with significant reduction in risk of pathogenic infection.

A New Synthetic Strategy to Prepare a Polyphosphazene with Charge-Transporting Agents and Nonlinear Optical Chromophores as Side Chains

A new strategy, a post coupling method to develop the polyphosphazene (P2) functionalized with carbazolyl groups and nonlinear optical (NLO) chromophores, has been explored. P2 exhibits good solubility in common organic solvents. The poled film of P2 exhibits a resonant d 33 value of 42 pm/V by second harmonic generation (SHG) measurements.