Tris 2,2,2-trifluoroethoxy

As can be seen, the first example of phosphoranimine polymerization process was proposed by E. P. Flindt and H. Rose [314] in 1977 for tris(trifluoroethoxy)-AT-(trimethylsilyl)phosphoranimine, which could be polymerized to poly[bis-(trifiuoroethoxy)phosphazene] (MW 4000-10,000) by simple heating at 200 °C. 

In addition, commercially available phenyltrimethoxysilane has been successfully cross-coupled with heteroaryl bromides including both bromopyridines and bromothiophenes [105], Both 2-bromopyridine and 3-bromopyridine were coupled with phenyltrimethoxysilane to give the corresponding phenylpyridines in 76% and 62% yield, respectively. Employing phenyl tris(trifluoroethoxy)silane, a siloxane with electron-withdrawing groups, did not improve the yields. 

Polymer (B) poly[P-tris(trifluoroethoxy)-N-trimethylsilyl] 19980NE... 

Phosphoranimine condensation was discussed in recent reviews and mechanistic studies. A step-wise progression is shown in Scheme 12. Poly (propyleneglycol) (PPG), terminated with amine groups, reacts with bis-tiifluormethylbromo-N-trimethylsilylphosphoranimine to form the PPG-phosphazene adduct. Oligomeric poly(dichlorophosphazene) is formed from the ambient temperature condensation of tris-trifluoroethoxy-N-trimethyl-... 

The molecular architecture of a polyphosphazene has a profound influence on properties. For example, linear and tri-star trifluoroethoxy-substituted polymers with the same molecular weight (1.2 x 104 or higher) have strikingly different properties.138 The linear polymers are white, fibrous materials that readily form films and fibers, whereas the tri-arm star polymers are viscous gums. One is crystalline and the other is amorphous. Cyclolinear polymers are usually soluble and flexible. Cyclomatrix polymers are insoluble and rigid. Linear polymers can be crystalline, but graft or comb polymers are usually amorphous. 

The principal polyphosphazenes that have been used in hydrogels are those with linear or branched ethyleneoxy side chains, aryloxy groups with carboxylic acid substituents, or mixed-substituent polymers that bear hydrophilic methylamino side groups plus a hydrophobic cosubstituent such as phenoxy or trifluoroethoxy. Cross-linking is usually accomplished by gamma-ray irradiation or, in the case of the carboxylic acid functional species, by treatment with a di- or tri-valent cation. Here, we will consider another example based on MEEP (3.79), a polymer that is well suited to the clean method of radiation cross-linking. 

N3C0O6QH12, Cobalt(III), tris(glycinato)-fac- and mer-, 25 135 N3C0O6C9HU, Cobalt(III), tris(alaninato)-fac- and mer-, 25 137 N3F,204P3CioHi4, PoIy[2,2-dimethyI-4,4,6,6-tetrakis(2,2,2-trifluoroethoxy)-catenatriphosphazene-1,6-diyI], 25 67 N3Fi204P3SiCi3H22, PoIy[2-methyl-4,4,6,6-... 

O4CSFS, Cesium fluorine sulfate, 24 22 04Fi2N3P3C,oHi4, Poly[2,2-dimethyl-4,4,6,6-tetrakis(2,2,2-trifluoroethoxy)catenatri-phosphazene-l,6-diyl], 25 67 04F,2N3P3SiCi3H22, Poly[2-methyl-4,4,6,6-tetrakise(2,2,2-trifluoroethoxy)-2-[(tri-methylsilyl)methyl]catenatriphospha-zene-l,6-diyl], 25 64... 

Lora et al, did try to enhance the biocompatibility of poly[bis(trifluoroethoxy)-phosphazenes] (PTFP) and poly[bis(phenoxy)phosphazenes] (PPP) by grafting different side groups on the polymer surface (Figpme 28). Graft copolymerization w ith dimethylaminoethylmethacrylate (DMAEM) onto the polyphosphazene surfaces highly enhances their biocompatibility. Subsequent heparinization has a negative effect, which is more appreciable with the PPP-based samples (Lora et al., 1991). Surface modification of poly[bis(trifluoroethoxy)phosphazene] with... 

Monomer Synthesis. Phosphoranimines bearing various combinations of 2-methoxyethoxy, 2-(2-methoxyethoxy)ethoxy and 2,2,2-trifluoroethoxy groups have been synthesized by the Staudinger reaction (9) between azidotrimethylsilane and the appropriately substituted phosphites. (11-14) Phosphites can be prepared via the reaction of the corresponding sodium alkoxide with tris-(2,2,2-trifluoroethyl)phosphite or from PCI3 and the appropriate alcohols in the presence of (CH3CH2)3N. 

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