Ambient-Temperature Direct Synthesis of Poly(organophosphazenes) via the “Living” Cationic Polymerization of Organo-Substituted Phosphoranimines

Abstract

A new, ambient-temperature method for the direct synthesis of organo-substituted polyphosphazenes is described. It involves the initiation of a series of organophosphoranimines R(R′)-with catalytic amounts of PCl5 in CH2Cl2 to yield (after treatment with NaOCH2CF3 in the case of 3) the corresponding polyphosphazene species (NdPRR′)n (4, R ) Ph, R′ ) OCH2CF3; 6, R) with narrow polydispersities. The molecular weights of the polyphosphazenes were controlled by altering the ratio of monomer to initiator. The polymer chains were found to be active after chain propagation since further addition of monomer resulted in the formation of higher molecular weight polymer. For monomers 7 and 9 optimum polymerization behavior was found to occur at 35 °C in the absence of solvent in the presence of catalytic quantities of PCl5. These reactions proceeded to 100% completion, while maintaining molecular weight control and narrow polydispersites. In the case of polymers 4, 8, and 10, which were synthesized with a 10:1 monomer to initiator ratio in CH2Cl2, the resultant polymers were analyzed by gel permeation chromatography (GPC) (4, Mn ) 2.9 × 10 3 , polydispersity (PDI ) Mw/Mn) ) 1.07); 8, Mn ) 2.2 × 10 3 , PDI ) 1.31; 10, Mn ) 7.8 × 10 3 , PDI ) 1.23). Poly(diphenylphosphazene), ( NdPPh2)n ( 6), was insoluble in common organic solvents and was characterized by magic angle spinning (MAS) solid state 31 P NMR spectroscopy. The effects of side group steric bulk, electron-withdrawing or -donating properties, and leaving group types on the ambient-temperature cationic induced polymerizations are discussed.

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…was reported 241 by combining the living anionic ROP route to PFS with the living cationic polymerisation of phosphoranimines [242][243][244] (see Scheme 16). This was achieved by capping living PFDMS anions with an excess of chlorodiphenylphosphine to give PFS-PPh2 after purification.…”

Salt-in-Polymer Electrolytes for Lithium Ion Batteries Based on Organo-Functionalized Polyphosphazenes and Polysiloxanes

“…A particularly interesting method (last one in Table 1) was reported in 1997 consisting of a cationic living polymerization of phosphazene monomers with PCl 5 as chain growth initiator [27]. However, at the beginning, it was quite difficult to synthesize the monomeric phosphazene with the necessary purity according to the available procedures [28].…”

Progress in Synthesis of Polyphosphazenes

“…This process is shown in Scheme 7 [22]. Some disadvantages of this method are that the polymerization has strict requirements with regard to the monomer that is used, the rigour conditions required to prepare the monomer and a relatively low molecular weight for the resultant polymer.…”