Pyrolysis Mechanism of a Cyclotriphosphazene-Based Flame-Retardant Epoxy Resin by ReaxFF Molecular Dynamics

Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP)incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method.The pyrolysis fragments,initial reaction pathways,and main products were identified for the EP and EP/HMPOP composites.The activation energies were derived by fitting the weight percentage curves for solid species during the pyrolysis reactions and the obtained values were in good agreement with experimental data.The initial EP pyrolysis reactions included four major decomposition modes,which primarily involved the cleavage of C–O and C–N bonds.The main pyrolysis products were H_(2)O,CO,C_(2)H_(4),and CH_(2)O.HMPOP bonded with the oxygen-containing fragments to form larger molecular fragments and reduced the amounts of C_(0)–C_(4) products,especially that of the harmful gas CH_(2)O.Thus,HMPOP promoted the formation of carbon clusters and reduced the generation of combustible gases,ultimately decreasing the capacity for fire propagation.

Polydentate cyclotriphosphazene ligands:Design,synthesis and bioactivity

Five multinuclear cyclotriphosphazene ligands were synthesized and tested for their cleavage activities to plasmid DNA. All of these new compounds were confirmed by MS, ^1H NMR, ^31P NMR, ^13C NMR and IR. Preliminary studies on the cleavage of pUC19 DNA in the presence of metal complexes were performed. The results revealed that these complexes could act as powerful catalysts under physiological conditions. The complexes 3b ＋ Cu can effectively cleave DNA to nicked form, giving hydrolysis rate constant of 0.08/h under physiological conditions. An acid-base catalyzed DNA phosphate-diester hydrolysis mechanism was also orooosed.

A Novel Synthesis of Some Hexasubstituted Cyclotriphosphazenes

Some known and new hexaaryloxyphosphazene: N3P3(O-C6H4-R)(1)/(R=H.CH.OCH3. C(CH3)(3). CHO.F.C6H5COOR. etc) were readily obtained with ca. 70% isolated yield in refluxing acetonitriie in the presence of anhydrous potassium phosphate. All compounds were characterized by means of elemental analysis. H-1-NMR.P-31-NMR sprctroscopy.

Fluoroscence Phenomena-New Properties of Hexakis(4-Aminophenoxy)Cyclotriphosphazene

Investigations of the absorption and fluorescence spectra of hexakis (4-aminophenoxy)- cyclotriphosphazene at room temperature in three solvents of different polarity (N, N-dimethyl- formamide, tetrahydrofuran and toluene) have been conducted. And fluorescence lifetimes of these three solutions were also measured. Major reasons of such spectral behavior are discussed.

The Synthesis of Cyclotriphosphazene Liquid Crystals

Four functional cyclotriphosphazene liquid crystals have been synthesized. Their phase transition temperatures have also been measured by polarizing textural observation and confirming by DSC.

Targeting PPAR<i>γ</i>Receptor Using New Phosphazene Derivative Containing Thiazolidinedione: Design, Synthesis, and Glucose Uptake

The peroxisome proliferator activator receptor-γ (PPAR-γ) remained the most effective target for management of diabetes mellitus. The present work endeavors rational designing new PPAR-γ agonist bearing cyclotriphosphazene and thiazolidine-2,4-dione scaffolds. Thiazolidinedione (TZD) derivatives are the novel class of oral antidiabetic drugs which are selective agonist for the nuclear PPARγ that enhances the transcription of several insulin responsive genes but TZDs are known to cause weight gain, hepatotoxicity and fluid retention. So, cyclotriphosphazene containing thiazolidine-2,4-dione was designed, synthesized as PPARγ agonist. The in-vitro antidiabetic activity showed that compound 8 has similar activity and exhibited higher glucose uptake in comparison to pioglitazone as reference drugs. This research opened new avenues for smart designing of molecules with high efficiency towards the management of hyperglycemia.

Lithium-based ionic liquids as novel lubricant additives for multiply alkylated cyclopentanes(MACs)

Two lithium-based ionic liquids(ILs,L-C3N3,and L-P3N3)were synthesized and evaluated as novel lubricant additives for multiply alkylated cyclopentanes(MACs).They were found to be approximately 1.0%soluble in MACs at room temperature(RT),whereas traditional ILs,such as 1-ethyl-3-methylimidazolium tetrafluoroborate(L-B102),1-hexyl-3-methylimidazolium hexafluorophosphate(L-P106),and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(L-F102),could not be dissolved in this base oil.Friction tests indicated that these ILs exhibit excellent friction-reducing and anti-wear properties both at RT and at 100°C.They can improve the tribological properties of MACs at RT to a greater extent than the commonly used lubricant zinc dialkyldithiophosphate(T204),even at a concentration of 0.1%.The load ramp test showed that MACs with L-C3N3 and L-P3N3 also exhibit high load-carrying capabilities.Scanning electron microscope(SEM)and X-ray photoelectron spectrometer(XPS)results indicated that physical adsorption and complex tribochemical reactions occurred between the ILs and metal surfaces during the sliding process,thereby forming a surface protective film that significantly contributed to the excellent tribological properties of the new ILs.

New flame retardant epoxy resins based on cyclophosphazene-derived curing agents

To obtain high-efficiency flame retardancy of epoxy resins,a cyclophosphazene derivative tri-(ohenylenediamino)cyclotriphosphazene(3 ACP)was successfully synthesized and used as a curing agent for the thermosetting of an epoxy resin system.The flame retardant properties,thermal stability,and pyrolysis mechanism of the resultant thermosets were investigated in detail.The experiments indicated that the synthesized thermoset achieved a UL-94 V-0 rate under a vertical burning test as well as a limiting oxygen index(LOI)of 29.2%,which was able to reach V-0 even when a small amount of 3 ACP was incorporated.Scanning electronic microscopic observation demonstrated that the char residue of the thermosets was extremely expanded after the vertical flame test.Thermal analysis showed that the samples had a lower initial decomposition temperature when 3 ACP was introduced into the epoxy resin systems.This indicates that the carbonization ability of the thermosets was significantly improved at elevated temperatures.In addition,the incorporation of 3 ACP can effectively suppress the release of combustible gases during the pyrolysis process,and the decomposition of E-44/DDS-3 ACP curing systems also promotes the formation of polyphosphoramides charred layer in the condensed phase.The investigation on the chemical structures of both the gaseous and condensed phase pyrolysis process confirmed the flame-retardant mechanism of the 3 ACP-cured epoxy resins.Therefore,the nonflammable halogen-free epoxy resin developed in this study has potential applications in electric and electronic fields for environment protection and human health.