Cyclotriphosphazenes

Thermal polymerization of hexachlorocyclotriphosphazene (LXXXIII) (also referred to as phosphonitrilic chloride) yields poly(dichlorophosphazene) (LXXXIV) (IUPAC poly[nitrilo (dichloro-Ls-phosphanetriyl)] or catena-poly[(dichlorophosphorus)- j,-nitrido]) [Allcock, 1976, 1986, 2002 Allcock and Connolly, 1985 Archer, 2001 De Jaeger and Gleria, 1998 Liu and Stannett, 1990 Majumdar et al., 1989, 1990 Manners, 1996 Potts et al., 1989 Scopelianos and Allcock, 1987 Sennett et al., 1986], 

A main feature of the melt polymerization is the sharp increase in electrical conductivity at temperatures ( 220°C) where polymerization occurs. This observation together with those described above support a cationic polymerization mechanism based on ionization of a P—Cl bond (Eq. 7-113) followed by electrophilic attack of P+ on monomer (Eq. 7-114). Boron 

Alkyl and aryl derivatives of poly(dichlorophosphazene) are not efficiently synthesized by nucleophilic reaction of LXXXIV with metal alkyls or aryls. The halogen substitution reaction occurs but is accompanied by polymer chain cleavage. Use of poly(difluorophosphazene) or introduction of aryl and alkyl groups at the monomer stage offer some improvement, but neither method is fully satisfactory. The best route to alkyl and aryl derivatives is polymerization of A-(trimethylsilyl)-/).P-dialkyl-.P-halophosphoranimines at moderate temperatures (25-60°C) in the presence of a Lewis acid [Allcock et al., 1996, 2000, 2001a,b Neilson and Wisian-Neilson, 1988]. The reaction proceeds as a cationic chain polymerization  

The phosphoranimine route also allows an alternate route to poly(dichlorophosphazene) by using lV-(trimethylsilyl)-/)/)/ -trichlorophosphoranimine as the monomer. The phosphoranimine route not only efficiently produces alkyl and aryl poly(phosphazene)s but also offers 

The polymerizations of other cyclic phosphazenes have also been studied, including car-bophosphazene, thiophosphazene, and thionylphosphazene [De Jaeger and Gleria, 1998 McWilliams et al., 2000] 

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Inclusion compounds of the Cg aromatic compounds with tris((9-phenylenedioxy)cyclotriphosphazene have been used to separate the individual isomers (43—47). The Schardinger dextrins, such as alpha-cyclodextrin, beta-dextrin, and gamma-dextrin are used for clathration alpha-dextrin is particularly useful for recovering PX from a Cg aromatic mixture (48,49). PyromeUitic dianhydride (50) and beryllium oxybenzoate (51) also form complexes, and procedures for separations were developed. 

Polypyromehitimide films based on cyclotriphosphazene and bisaspartimide-derived diamines have shown thermal stabiUties up to 800°C and char yields of 56—68% in N2 and 24% in air (29). High strength fine- and heat-resistant imide resins containing cyclotriphosphazene and... 

The first phosphazene polymers containing carbon (79), sulfur (80,81), and even metal atoms (82) in the backbone have been reported. These were all prepared by the ring-opening polymerization of partially or fully chloro-substituted (or fluoro-substituted) trimers containing one hetero atom substituting for a ring-phosphoms atom in a cyclotriphosphazene-type ring. 

Bis(3,5-dimethylpyrazol-l-yl)cyclotriphosphazene containing phenyl substituents at the phosphorus atoms (R) reacts with molybdenum and tungsten hexacar-bonylstogive34(R = Ph M = Mo, W) [94JCS(D)63]. IfRj = N(Me)(CH2)20, compounds 34 (R2 = N(Me)(CH2)20 M = Mo, W) having better solubility in organic solvents are produced. Their structures show the novel tridentate NNN feature of the ligands. 

Allcock HR and Fuller TJ. Synthesis and hydrolysis of hexakisumidazolyl)-cyclotriphosphazene. J Am... 

Polymers with -CH20(CH2CH20)n- spacers (n=l,2) between the polystyrene backbone and the pendant penta(methoxyethoxyethoxy)cyclotriphosphazene... 

The polynorbornenes X bearing cyclotriphosphazenes with -0(CH2CH20)x-CH3 (x=l, 2,3,7.2) side groups have been prepared via ring opening metathesis polymerization (ROMP) and complexed with LiS03Cp3 and LiN(S02Cp3)2 (10-60% molar ratios) by Allcock [619,620]. 

Table 16 Maximum conductivity of polynorbornenes bearing cyclotriphosphazenes/lithium salt systems at 30 °C...

Multi-armed polymers with a cyclotriphosphazene core XI and XII have been synthesized from the reaction of polyethylene glycol monomethyl ethers with acid chlorides of hexakis(3,5-dicarboxyphenoxy) and hexakis(4-carboxyphe-noxy) cyclotriphosphazenes. Their complexes with LiC104 were investigated, and their maximum conductivities are reported in Table 17 [621]. 

In the systems with polystyrene derivatives VIII, IX and multi-armed cyclotriphosphazenes XI, XII the conductivity seems to be dependent on the relative concentrations of inter- and intra-molecular complexes (Table 17). 

Table 17 Maximum conductivity of multiarmed cyclotriphosphazene/LiCl04 systems...

Allcock, H. R., Schmutz, J. L., and Kosydar, K. M., A new route for poly(organophosphazene) synthesis. Polymerization, copolymerization, and ring-ring equiUbration of trifluoroethoxy-and chloro-substituted cyclotriphosphazenes, Macromolecules. 

Allcock, H. R., and Connolly, M. S., Polymerization and halogen scrambling behavior of phenyl-substituted cyclotriphosphazenes. Macromolecules. 18, 1330, 1985. 

Aerosols of Cellulube 220 produced deaths associated with severe dyspnea and mild diarrhea in one of two rabbits exposed to 2,000 mg/m3 for <4 hours/day, 5 days/week for 11 or 22 days (Carpenter et al. 1959). Continuous exposure for 30-160 days to aerosols of a triaryl phosphate U.S. military hydraulic fluid (see Table 3-2), at concentrations <110 mg/m3, produced no deaths in dogs or rats, but deaths associated with severe neurotoxic symptoms occurred in chickens exposed to concentrations >23 mg/m3 and in rabbits exposed to 102 mg/m3 (Siegel et al. 1965). Aerosols of Durad MP280 or Fyrquel 220 (continuous exposure for 90 days) produced no deaths in rats or hamsters exposed to 100 mg/m3. Deaths associated with lethargy, cachexia, and head droop occurred in rabbits exposed to 101 mg/m3 Durad MP280, but not in rabbits exposed to 100 mg/m3 Fyrquel 220 (MacEwen and Vemot 1983). Some of the Durad MP280-exposed rabbits were also infected with Pasteurella, which may have contributed to neurological symptoms. No deaths occurred in rats exposed to cyclotriphosphazene at 990 mg/m3, 6 hours/day,... 

No deaths occurred in rats after dermal exposure to Durad 220B, Durad 300, or Durad 110 under occluded conditions for 24 hours at dosage levels of 2,000 mg/kg (FMC 1990a). Dermal exposure to 2,890 mg/kg doses of a cyclotriphosphazene hydraulic fluid for 24 hours under occluded conditions likewise produced no deaths in rabbits (Kinkead et al. 1992c MacEwen and Vernot 1985). Deaths associated with severe cholinergic symptoms and symptoms of delayed neuropathy occurred in a group of 50 cattle treated dermally with about 1.52 L of waste from reclamation of a Fyrquel hydraulic fluid (Julian et al. 1976). 

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