Abstract: Phosphazene polymers having the units ##STR1## wherein the total number of units ranges from about 3 to about 50,000, R.sub.1 and R.sub.2 are different and are C.sub.1 to C.sub.12 linear or branched alkyl, C.sub.2 to C.sub.15 linear or branched fluoroalkyl or mixtures thereof, and R.sub.3 is phenyl substituted with C.sub.1 to C.sub.12 linear or branched alkyl. The polymers can be cured with peroxides to yield cross-linked materials having enhanced elongation.

Abstract: A drilling fluid includes water, bentonite, a weighting agent, and an additive comprising a water-soluble polycondensate containing phosphorous and nitrogen such as phosphorylated-urea-formaldehyde or phosphorylated-melamine-formaldehyde. Such additives provide the desired rheological and filtration loss properties as well as thermal and shear stability. The additives are prepared by reacting phosphorous acid, urea and formaldehyde according to a Mannich-type reaction.

Abstract: The synthesis of a new class of macromolecules, the polycarbophosphazenes, is reported. When heated at 120.degree. C., the cyclocarbophosphazene N.sub.3 P.sub.2 CCl.sub.5 undergoes ring-opening polymerization to afford the high polymeric polycarbophosphazene [N.sub.3 P.sub.2 CCl.sub.5 ].sub.n. The latter functions as a reactive macromolecular intermediate and undergoes halogen replacement with sodium phenoxide or aniline to afford the hydrolytically stable derivatives [N.sub.3 P.sub.2 C(OPh).sub.5 ].sub.n and [N.sub.3 P.sub.2 C(NHPh).sub.5 ].sub.n.

Abstract: Silane esters are transesterified with hydroxyl-terminated polyester resins to obtain end-capped, extended or branched polyester molding compositions.

Abstract: Epoxy resins can be cured or crosslinked with trihydrocarbyl phosphine oxide compounds having epoxy-reactive (active hydrogen) substituents either alone or in combination with amine-terminated polyarylene ethers (e.g., amine-terminated polysulfone oligomers or high polymers.

Abstract: Polyphosphazene derivatives containing carbonyl groups which are apt to undergo rapid photoreticulation processes having the general formula ##STR1## in which: X represents substituents bound to the polyphosphazene chains by means of hydroxy or amino functions, and containing carbonyl groups;X' represents additional substituents bound to the polyphosphazene chain through hydroxy or amino functions and containing one or more easily extractable hydrogen atoms;(w+y+z) is an integer between 20 and 15,000;w and z are integers greater than or equal to 0 and always lower than 15.000;y is an integer between 20 and 15,000.

Abstract: An improved process for producing sulfur-cured polyphosphazene foams is disclosed. The process comprises foaming more than one storable, stable accelerator base composition comprising the sulfur curing agent, a phosphazene oil and a polyphosphazene. A masterbatch of the same or similar polyphosphazene is made by mixing together a hydrated filler, processing aids and phosphazene oil. The matchbatch and accelerator base composition are then blended and foamed and cured.

Abstract: A novel phosphazene polymer having Schiff base structures is disclosed. The polymer is a condensation reaction product of a cyclic phosphonitrilic compound represented by the general formula (I): ##STR1## (wherein n is an integer 3 or 4, and 2n A's are independently selected from a group consisting of a formylphenoxy group, a phenoxy group, an alkylphenoxy group, a halogenated phenoxy group, an N-aromatic azomethine-phenoxy group, and a fluoroalkoxy group, provided more than 2 formylphenoxy groups being contained per molecule on the average) and a primary diamine or a primary polyamine, The polymer contains Schiff base bonds derived from formylphenoxy groups and amines and is represented by the formula: ##STR2## (wherein Z is a residual group said primary diamine or primary polyamine and may have bonds other than those indicated). The polymer exhibits a 20% or less weight loss under thermobalance analysis at 400.degree. C. and has a glass transition teperature (Tg) of 120.degree. C. or higher.

Abstract: A shaped polyphosphazene article having a modified surface portion thereof and exhibiting a desired property and/or performance comprises a polyphosphazene polymer having at least 50 molar % or more of repeating units of the formula (I): ##STR1## wherein R.sup.1 and R.sup.2 in the first and second side chains --OR.sup.1 and --OR.sup.2 respectively represent, independently from each other, an aliphatic, cycloaliphatic or aromatic radical, and having at least a portion of a surface portion thereof in which at least 5 molar % of the first and second side chains are converted to one or more types of third side chains --OR.sup.3 wherein R.sup.3 represents an aliphatic, cycloaliphatic or aromatic radical and which are different from --OR.sup.1 and --OR.sup.2.

Abstract: The present invention relates to an improved process for the synthesis of polyphosphazenes in which catalytic amounts of a compound selected from the group consisting of toluenesulfonic acid, sulfabenzoic acid, ammonium sulfamate and sulfamic acid, and preferably an effective amount of a promoter compound selected from the group consisting of CaSO.sub.4.2H.sub.2 O, CuSO.sub.4.2H.sub.2 O, NiSO.sub.4.2H.sub.2 O, CoSO.sub.4.2H.sub.2 O, MgSO.sub.4.2H.sub.2 O and Al(OH).sub.3, are added to a reaction mixture of hexachlorocyclotriphosphazene and 1,2,4-trichlorobenzene.

Abstract: An improved process for the preparation of highly fluorinated phosphonitrilic elastomers is disclosed. The fluoroalkoxy substituents on phosphonitrilic fluoroelastomers which contain some or all fluoroalkoxy groups in which the terminal carbon bears one or more hydrogen atoms are exchanged with fully fluorinated alkoxide groups in which the terminal carbon bears three fluorines. The process is accomplished using a ligand replacement mixture of an alkali metal fluoroalkoxide of the formula MOC.sub.n.sup.f and a fluoroalcohol of the formula HOC.sub.n.sup.f' where C.sub.n.sup.f is --(CH.sub.2).sub.y (CF.sub.2).sub.n CF.sub.3 where y is an integer 1 or 2 and n is an integer from 0 to 20 and C.sub.n.sup.f' is the same or different from C.sub.n.sup.f where C.sub.n.sup.f' is --(CH.sub.2).sub.y (CF.sub.2).sub.n CF.sub.3 where y and n are as previously defined.

Abstract: A process for treating the surface of a cured phosphonitrilic fluoroelastomer of the formula ##STR1## where x is an integer of from about 3 to about 50,000, Q and Q' are the same or different and are fluoroalkoxy of the formula --OCH.sub.2 (CF.sub.2).sub.m CF.sub.2 Z where m is an integer from 0 to 20 and Z is hydrogen or fluorine and Q" is a group having some olefinic unsaturation with a solution of an alkali metal fluoroalkoxide of the formula MOC.sub.n.sup.f where M is an alkali metal and C.sub.n.sup.f is a fluorocarbon moiety of the formula --(CH.sub.2).sub.y (CF.sub.2).sub.n CF.sub.3 where y is 1 or 2 and n is an integer from 1 to 20. The process of this invention causes the replacement of some of the Q and Q' groups with --OC.sub.n.sup.f. The decreased number of Q and Q' where Z is hydrogen results in a cured phosphonitrilic fluoroelastomer surface displaying improved resistance to polar solvents.

Abstract: Piezoelectric materials characterized by consisting essentially of crosslinked polyphosphazenes obtained by bringing polyphosphazenes which have repeating structural units represented by the general formula [I]--NP(X).sub.a (Y).sub.b -- [I](all the symbols are as defined in the appended claims) into oriented state in an electric field provided by applying high voltage on them and then crosslinking them under such conditions.Piezoelectric materials thus obtained display an excellent piezoelectric effect and, in addition, rubber elasticity.

Abstract: A cover layer for micro-electronic components and VLSI circuits is provided for protecting the components and circuits against alpha radiation. The cover layer is produced by ultraviolet cross linking of a negative resist, wherein, as a constituent for absorbing the alpha rays, the negative resist contains a substituted triphosphazene of the formula (I) whose organic radicals are bonded to phosphorus via oxygen and wherein, on a statistical average, 1 through 3 radicals have cross-linkable, light-sensitive groups. The cover layer provided good protection from alpha rays, has low shrinkage during curing and, given high thermal resistance, can be combined when mixing with other negative resists.

Abstract: Polyfluoroalkoxyphosphazenes cured through eugenoxy groups result in elastomer compositions having higher modulus, tensile strength and elongation retention and lower compression set compared to a similar polyfluoroalkoxyphosphazene cured through conventional ortho-allylphenoxy groups.

Abstract: Substantially linear organophosphazene polymers containing randomly distributed repeating units represented by the formulas: ##STR1## wherein R.sub.1 is a fluoroalkoxy group having the structure:F.sub.3 C--(CF.sub.2).sub.n --CH.sub.2 O--wherein n is 0 or an integer from 1 to 20 and X is fluorine and wherein at least 3 of the R.sub.1 units are different from each other and R.sub.2 represents a group with some unsaturation which enhances the curability of said polymers and represented by the formula: ##STR2## wherein R.sub.3 is an unsaturated monovalent group and R.sub.4 is selected from the group consisting of hydrogen, alkyl and alkoxy, the total number of said units ranging from 3 to about 100,000 and the R.sub.2 groups being present in an amount sufficient to enable cure of said polymers and in the range of about 0.01-50 mole percent of the total number of R.sub.1 and R.sub.2 groups are claimed.

Abstract: Various kinds of organophosphazene polymers are produced by reacting dichlorophosphezene polymer with hydroxy compounds using a tertiary amine such as triethyl amine as an acid acceptor in the presence of pyridine derivative such as 4-dimethylaminopyridine as a catalyst under mild reaction conditions to substitute substantially all the chlorine atoms with organic groups.

Abstract: Novel thermoset polymers are prepared by reacting an allyl or vinyl aryl or aryloxy substituted cyclophosphazene with a bis-maleimide.

Abstract: Polyfluoroalkoxyphosphazenes cured through eugenoxy groups result in elastomer compositions having higher modulus, tensile strength and elongation retention and lower compression set compared to a similar polyfluoroalkoxyphosphazene cured through conventional ortho-allylphenoxy groups.

Abstract: Polyorganophosphazenes having at least some N-(acryloxyhydrocarbyl)carbamyloxyhydrocarbyloxy groups:H.sub.2 C.dbd.CHR--C(O)O--R--NH--C(O)O--R--O--bonded to phosphorus can be cross-linked by exposure to ultraviolet radiation.

Abstract: The present invention relates to a method of preparing linear polyphosphazene polymers by direct synthesis under anhydrous conditions from NH.sub.4 Cl and at least one chlorophosporous compound selected from the group consisting of PCl.sub.5, XPCl.sub.4, or X.sub.2 PCl.sub.3 wherein X is one or more substituents selected from the group consisting of C.sub.6 H.sub.5 -, C.sub.6 H.sub.4 Cl-, C.sub.6 H.sub.4 F-, C.sub.6 H.sub.4 Br-, C.sub.6 H.sub.2 Cl.sub.3 -, C.sub.6 F.sub.5 -, C.sub.6 H.sub.4 CF.sub.3 -, C.sub.6 H.sub.4 NO.sub.2 -, Cl.sub.3 C-, F.sub.3 C-, F.sub.5 C.sub.2 -, F.sub.7 C.sub.3 -, or HC.sub.2 F.sub.4 -. Each of these compounds may be prepared in situ in a reactor. The instant process controls the pressure in the reactor through continuous venting of by-product HCl at elevated pressures. The instant invention also utilizes an excess of of reactive solvent such as PCl.sub.3, XPCl.sub.2, or X.sub.2 PCl as X is defined above.

Abstract: A biocompatible polyester comprising repeating units derived from glycerophosphorylcholine or glycerophosphorylethanolamine and at least one di- or poly-functional acid or reactive derivative thereof is haemocompatible and may be used in components for handling body fluids and in prostheses.

Abstract: Phenolic impurities are removed from polyaryloxyphosphazenes by extracting a solution of the crude polyaryloxyphosphazene with an aqueous lower alcohol alkali metal base solution such as aqueous methanolic sodium hydroxide.

Abstract: Improved flame retardant coatings are produced from curable chemical mixtures having at least one phosphorus-containing film former which has hydroxyl and/or methylol functionalities, and at least one nucleophilic organo silane. The silane is capable of undergoing nucleophilic reaction with hydroxyl radical displacement and/or capable of Michael's addition type of reaction via a nucleophilic phosphine compound. Additionally, the curable chemical mixture can involve an interaction polymeric product of the phosphorus-containing film former and nucleophilic organo silane. Also solvents such as water, curing agents, fillers and/or extenders may be present in the mixture.

Abstract: Highly fire resistant composites or laminates particularly applicable as structural components in aircraft, e.g. in the engine nacelle, as part of the acoustic panel-fire wall structure, and capable of withstanding a 2,000.degree. F. flame temperature, comprising incorporating an additive in the form of a polymeric phosphorylated amide, into a resin, e.g., a polyimide or an epoxy resin, such additive being soluble in the resin. The resulting resin containing the additive is then applied to or impregnated into a substrate such as glass fiber cloth or graphite fiber, to form a composite structure which is then cured. The resulting cured composite when subjected to high temperatures of the order of, e.g., a 2,000.degree. F. flame temperature, forms a resin char of reduced thermal conductivity which holds the fibers of the laminate together and maintains the structural stability and integrity of the laminate.

Abstract: High molecular weight non cross-linked polyfluoroalkoxyphosphazenes containing some unsaturated groups can be cured (i.e. cross-linked) by contact with a catalyst consisting essentially of platinum, a platinum halide or a haloplatinic acid or their hydrates (e.g. chloroplatinic acid hydrate).

Abstract: Polyphosphazene homopolymers and copolymers containing repetitive units represented by the general formula: ##STR1## in which the substituents X, which can be equal or different, are represented by the following formulas: ##STR2## where R is hydrogen or a C.sub.1 -C.sub.5 alkyl group or an aryl or heterocyclic group, with or without substituents, R' is CH.sub.2 or an aryl or heterocyclic group, with or without substituents, n is zero or a whole number variable from 1 to 5 and Y is hydrogen or a halogen or a methyl, nitroso or nitro group; the substituents X.sup.1 are groups equal to X or halogen, or alkoxy, aryloxy, amino or mercapto groups, either substituted or unsubstituted, or a mixture thereof; the sum (w+y+z) has a value varying from 20 to 50,000.The polymers of the present invention are prepared from the corresponding poly(dichlorophosphazenes) of general formula (NPCl.sub.2).sub.m in which m can vary from 20 to 50,000, and can be used as photoconductor materials and for other uses.

Abstract: Polyetheroxy-substituted polyphosphazenes useful in making solid electrolytes are purified by dissolving the impure polyphosphazene in water at a low temperature (e.g. below 40.degree. C.) and heating the water solution to a temperature high enough to cause the purified polyphosphazene to precipitate (e.g. above 50.degree. C.).

Abstract: Disclosed are thermosettable compositions comprising (A) an epoxy resin such as the diglycidyl ether of bisphenol A; (B) boron trifluoride complexed with a primary, secondary or tertiary amine such as monoethanolamine and (C) at least one cyclic or acyclic phosphazene having at least one pendant ##STR1## group wherein Z is an alkyl or an aryl group such as hexa(n-propylamino)cyclotriphosphazene.When cured, these compositions have an increased glass transition temperature (Tg) value as compared to a similar composition without the phosphazene compound.These compositions are useful in potting compositions, wet lay-up and pre-impregnated laminate, adhesive, molding, coating, casting, encapsulation, filament winding and transfer molding applications.

Abstract: Alkoxyphosphazene polymer is prepared in a homogeneous system by admixing chloropolymer dissolved in cyclohexane or a mix of cyclohexane and C.sub.5 -C.sub.7 alkane with alkali metal alkoxide dissolved in tetrahydrofuran, reacting, desalting the resulting reaction solution and concentrating by a first step involving admixing non-solvent which is cyclohexane (and/or C.sub.5 -C.sub.7 alkane if that is also present in the reaction solution) to cause coagulation thereby forming a higher viscosity rubber phase enriched in polymer and a lower viscosity liquid phase depleted in polymer and separating the rubber and liquid phases and a second step involving evaporating the residual solvent and non-solvent. The first concentrating step is preferably carried out utilizing an extruder.

Abstract: This invention is directed to organophosphorus compounds useful as epoxy curing agents and adhesion promoters.

Abstract: A functional fluid composition is provided which comprises a plurality of different phosphazene compounds of the general formula (P=N).sub.n (R).sub.a (R').sub.b (R").sub.c (R'").sub.d wherein R is at least one alkoxy moiety described by the general formula --OCH.sub.2 (CF.sub.2).sub.y X, with X being hydrogen or fluorine and y being equal to 1 to about 10; R', R" and R'" are different aryloxy moieties, each of R', R" and R'" being selected from the group consisting of phenoxy, alkoxy phenoxys, alkyl phenoxys, chlorinated phenoxys, fluorinated phenoxys, aryl phenoxys, phenoxy phenoxys, fluoroalkyl phenoxys, fluoroalkoxy phenoxys, chlorinated phenoxy phenoxys, fluorinated phenoxy phenoxys and mixtures thereof; n is equal to 3 to about 4 for each of said phosphazene compounds, each of a, b, c and d is equal to or greater than zero such that the sum a+b+c+d is equal to 2n; and for the composition as a whole, the average value of each of a, b, c and d is greater than 0.

Abstract: Compounds having the general formula 1 ##STR1## wherein X and Y are functional groups, preferably amino groups, are polymerized with, for example, polyfunctional epoxides to provide heat and fire resistant polymers useful for making flame and fire resistant polymer structures such as for aircraft secondary structures. The groups R in 1 are preferably alkyl and lower halo (e.g., chloro) alkyl.

Abstract: A dental filling composite material is disclosed, which contains 10-99% by weight of phosphazene of the formula: ##STR1## in which at least one of R.sub.1 and R.sub.2 represent radicals having not less than 3 carbon atoms and being polymerizable.The filling composite material is low in polymerization shrinkage, thermal expansion coefficient and water absorption and may be quickly polymerized and cured to form a polymer of high compressive strength, flexural strength and hardness.

Abstract: Polyphosphazene polymers are prepared which contain repeating units represented by the formulas: ##STR1## wherein X is --N(CH.sub.2 CHCH.sub.2).sub.2, and X' is a substituted or unsubstituted alkoxy, aryloxy, amino or mercapto substituent group or mixtures thereof which are compatible with diallylamino substituent and are known in the state of the art of polyphosphazene technology; and 20.ltoreq.(w+y+z).ltoreq.50,000 per polymer and (y+z)>0.The polymers of the invention can be utilized to form protective films and can also be utilized in applications such as for molding, coatings, foams and the like.

Abstract: Process for compounding polyphosphazene gum by (a) mixing a composition comprising a curable polyphosphazene gum, filler, plasticizer and other conventional components but without any curing agent to form a non-curing masterbatch, (b) mixing a composition comprising a polyphosphazene gum and an excess amount of curing agent, at least 10 times that required to cure the phosphazene gum in this mixture and optionally containing other conventional components to form a concentrate and (c) blending the non-curing masterbatch from (a) with sufficient concentrate from (b) to provide an amount of curing agent sufficient to cure the entire resultant mixture.

Abstract: A reaction product of a phosphazene and an amine terminated reactive liquid polymer. The phosphazene and the reactive liquid polymer are combined under agitation to produce a cured, cross-linked, reactive liquid polymer including bonded phosphazene groups providing a desirable elastomeric performance over a broad range of temperatures including temperatures substantially below freezing.

Abstract: Shown are fully alkylated/arylated polyphosphazenes having side units bonded to the phosphorus backbone by direct carbon-phosphorus bonds. A method of preparing the polyphosphazenes includes the thermal decomposition of and elimination of silanes from suitably constructed N-silylphosphinimines.

Abstract: Epoxy resins are disclosed which are the dehydrohalogenated reaction products of an epihalohydrin and a phosphoramide.

Abstract: A thermistor using an organophosphazene polymer having aryloxyl and/or alkoxyl group pendants as a thermo-responsive material. The organophosphazene polymer has an excellent responsiveness to temperature change, and can be molded into desired forms. The thermistor having good reliability and good heat and flame resistances can be prepared with good processability and in good yield.

Abstract: Carboranylmethylene-substituted cyclophosphazenes which can be thermally polymerized into carboranylmethylene-substituted phosphazene polymers, useful as thermally stable coatings and, due to the characteristics of these polymers in acting as a ligand for transition metals, metallocarboranylmethylene phosphazene polymers which can act as immobilized catalyst systems, and are electrically conductive and superconductive.

Abstract: A carboxylated phosphazene polymer, comprising a phosphazene polymer backbone covalently coupled to a carboxylate-containing compound through a divalent organic radical attached at one end to the carboxylate by an amide bond formed at a primary aliphatic amino group of the radical and at the other end to a phosphorous of the phosphazene backbone.

Abstract: Polymer-bound dyes have been prepared by the diazotization of high polymeric [NP(OC.sub.6 H.sub.5).sub.x - (OC.sub.6 H.sub.4 NH.sub.2 -p).sub.y ]n, followed by coupling to phenol, .beta.-naphthol, 6'-NaO.sub.3 S-.beta.-naphthol, and p-aminophenylnaphthalene. These reactions were preceded by model compound studies with the cyclic trimer [NP(OC.sub.6 H.sub.4 NH.sub.2 -p-).sub.2 ].sub.3. In both cases, the aminophenoxy units were generated by reduction of 4-nitrophenoxy groups with the use of PtO.sub.2 and hydrogen. The phosphazene skeleton was unaffected by the reduction, diazotization, and diazo coupling processes. The physical characteristics of the trimers and high polymers are described.

Abstract: Shown are fully alkylated/arylated polyphosphazenes having side units bonded to the phosphorus backbone by direct carbon-phosphorus bonds. A method of preparing the polyphosphazenes includes the thermal decomposition of and elimination of silanes from suitably constructed N-silylphosphinimines.

Abstract: Polyester polymers and copolyester polymers incorporating flame retardant amounts of cyclotri (or tetra) phosphazenes. These cyclotri (or tetra) phosphazenes can be added at the start of ester interchange, prior to, for example polycondensation and conventional melt spinning, or if desired, after polycondensation but before melt spinning. Specific examples of cyclotriphosphazenes and cyclotetraphosphazenes are hexa(dialkylphosphinylmethyleneoxy)cyclotriphosphazene, octa(dialkylphosphinylmethyleneoxy)cyclotetraphosphazene, tris(alkylphosphinyldimethyleneoxy)cyclotriphosphazene, tetra(alkylphosphinyldimethyleneoxy)cyclotetraphosphazene, hexa(dialkylphosphinylmethylene)cyclotriphosphazene, and octa(dialkylphosphinylmethylene)cyclotetraphosphazene.

Abstract: A process for preparing polyphosphazene polymers containing fluoroalkoxy and/or aryloxy substituents is provided. The process involves the reaction of a fluoroaliphatic alcohol or a substituted or unsubstituted aromatic alcohol or mixture of such alcohols with sodium hydroxide in an organic solvent or mixture of organic solvents which under appropriate conditions will form an azeotrope with water produced by the reaction. Water produced by the reaction is removed from the reaction mixture by azeotropic distillation thereby producing substantially dry sodium salts of said alcohols. The substantially dry sodium salts of the alcohols are then reacted with a linear polydichlorophosphazene polymer to produce polyphosphazene polymers containing fluoroalkoxy and/or aryloxy substituents.

Abstract: A coating of organo-phosphonitrile polymer is bonded to the surface of a cured rubber article such as a catheter with a primer coating containing a cross-linked di- or poly-vinyl compound.

Abstract: The curing or cross-linking of fluorinated alkoxy phosphonitrile polymers with organic peroxides is accelerated by the use of a trialkyl aluminum or a dialkyl aluminum hydride. The coating with such polymers of biomedical articles such as embolectomy catheters or Foley retention catheters made of natural or synthetic rubber is facilitated by using for the coating a solution of such polymers in an organic solvent together with an organic peroxide and the new accelerating catalyst.

Abstract: Carboranyl-substituted polyphosphazenes are prepared by heat polymerizing a carboranyl halocyclophosphazene at 250.degree. C. for about 120 hours in the absence of oxygen and moisture. The cyclophosphazene is obtained by allowing a lithium carborane, e.g. the reaction product of methyl-o-carborane with n-butyllithium in ethyl ether, to react with e.g. hexachlorocyclotriphosphazene at ambient temperatures and in anhydrous conditions. For greater stability in the presence of moisture, the chlorine substituents of the polymer are then replaced by aryloxy or alkoxy groups, such as CF.sub.3 CH.sub.2 O--.The new substantially inorganic polymers are thermally stable materials which produce a high char yield when exposed to extreme temperatures, and can thus serve to insulate less heat and fire resistant substances.

Abstract: An ionized gas plasma is established in an electrical field in contact with a non-vapor volume monomer (liquid and/or solid). The plasma causes polymerization of the monomers which are of the phosphazene or carborane type.