Polyphosphazenes, synthesis

Potin P and Jaeger RD. Polyphosphazenes Synthesis, structures, properties, applications. Eur Polym J, 1991, 415, 341-348. 

Allcock, H. R., and Kwon, S., Glyceryl polyphosphazenes Synthesis, properties, and hydrolysis. Macromolecules. 21. 

The primary polyphosphazene synthesis processes discussed above provide access to an enormous variety of different macromolecules. Yet further structural diversity can be achieved by carrying out modification reactions on the organophosphazene polymers produced in these primary rections. Secondary reactions are particularly important for the preparation of polymers with functional units in the side group structure, species that would be difficult or impossible to produce by the primary synthesis methods. 

Polyphosphazene synthesis provides additional possibilities for preparing liquid crystal polymers with different properties. As noted above, the substitution process (Figure 2) enables one to synthesize a wide variety of polymers. The phosphazene inorganic backbone Is a highly flexible polymer chain glass transition temperatures can... 

Singler RE, Schneider NS, Hagnamer GL (1975) Polyphosphazenes synthesis-properties-applications. Polymer Eng. Sci. 75 321... 

The macromolecular substitution route for polyphosphazene synthesis allows a wide variety or simple or complex organic side groups to be linked to the backbone. 

Scheme 1. Reaction sequences involved in polyphosphazene synthesis. The key reaction intermediate is poly(dichlorophosphazene) (4) which serves as a reaction platform for replacement of P-Cl bonds by P-organic side group structures. Tunability of properties comes through substitution after...

THE ROLE OF FLUORINE IN POLYPHOSPHAZENE SYNTHESIS CHEMISTRY B-Block... 

Fig. 2 Polyphosphazene synthesis scheme developed by Allcock a trimer synthesis, b ringopening polymerization, and c macromolecular nucleophilic substitution...

Other methods of polyphosphazene synthesis have also been reported [17]. The most interesting is the living cationic condensation polymerization of phosphoranimines [21,22] as it offers access to polyphosphazenes with controlled molecular weight, low polydispersity, and more complex architectures, e.g. block or graft copolymers. At the present time, only moderate molecular weights (Mw = 10 -10 ) are available via the condensation route. 

FIG. 3.22 Polyphosphazene synthesis scheme developed by AUcock (a) trimer synthesis, (b) ring-opening polymerization, and (c) macromolecular nucleophiUc substitution. 

Singler, R.E., Schneider, N.S., Hagnauer, Gi. (1975) Polyphosphazenes synthesis, properties, applications. Polymer Engineering Science, 15, 321 338. 

Andrianov, A.K., Chen, J., LeGolvan, M.P. (2004) Poly(dichlorophosphazene) as a precursor for biologically active polyphosphazenes synthesis, characterization, and stabilization. Macromolecules, 37, 414—420. 

The most striking difference between conventional polymers and poly(organophosphazenes) is in their method of synthesis. The normal techniques for the synthesis of macromolecules - i.e. the polymerization of unsaturated monomers or the condensation reactions of difunctional monomeric reagents - are not applicable to polyphosphazene synthesis. Monomers of structure, N=P(0R)2, N = P(NHR)2, N = P(NR2)2> N=PR2, have not yet been isolated. 

FIGURE 7.2 Scheme of polyphosphazene synthesis via macromolecular substitution. 

Alternative methods of polyphosphazene synthesis also exist (12-15) and several of these approaches are discussed elsewhere in this volume. Finally, chemistry conducted at the surface of polyphosphazenes allows the tailoring of those surfaces to achieve the development of specific chemical, physical, or biological characteristics (16-20),... 

---