Polymerization of NPC

Polycondensation of the monophosphazene Cl3P=NP(0)Cl2 occurs either in the bulk or in trichlorobiphenyl solution to afford the linear uncrosslinked polymer [NPC ln- A by-product viz., POCI3 is formed in this polymerization process. Polymers with molecular weights of up to 800,000 can be prepared by this method. 

Cationic polymerization of the iV-silylphosphoranimine Cl3P=NSiMe3 by initiators such as PCI5 afford a living polymer. High-molecular-weight [NPCl2]n (10 ) with very narrow PDFs (1.01-1.18) are accessible from this approach. 

Substituted chloro- and fluorocyclophosphazenes can also be polymerized to their high polymers by the ROP method. Several alkylcyclophos-phazenes such as N3P3CI5R, have been polymerized. These can be prepared from the corresponding hydridophosphazenes (see Eq. 3.48). 

Monosubstituted fluorocyclophosphazenes such as N3P3FsPh and N3P3F5tBu can be pol5anerized by ring-opening polymerization to the corresponding polymer (see Eq. 3.50). 

Some disubstituted cyclophosphazenes such as [ NPCl2 2 NP(R)(CH2SiMc3) ] have also been polymerized by the ringopening method to afford the linear polymers (see Eq. 3.51) [29]. 

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