Random copolymers, polyphosphazene

The synthesis of N-silyl-phosphoranimines bearing mixed alkoxyalkoxy and trifluoroethoxy substituents is reported. The polymerization kinetics and the proposed anionic mechanism are also discussed. These monomers are utilized for the preparation of polyphosphazene random copolymers by the simultaneous polymerization of two phosphoranimines. Block copolymers have also been synthesized by addition of a second phosphoranimine after conversion of the first. Evidence for copolymer formation includes and 3lp NMR, SEC, solubility and DSC data. The differences between analogous random and block copolymers are discussed. 

A random copolymer can be formed by postpolymetization reaction with a mixture of reagents, eg, in the case of polyphosphazenes (eq. 37) (45,46). 

Modifications in the preparation of polyphosphazenes by the condensation polymerization of N-silylphosphoranimines are also reported. The preparation of a series of new poly(alkyl/arylphosphazenes), relevant chemistry of the Si-N-P precursors, and catalysis by phenoxide anions are presented (NeUson, Chapter 18). Matyjaszewski (Chapter 24) discusses the use of fluoride catalysts to prepare polyphosphazene random and block copolymers with alkoxy and fluoroethoxy substituents and proposes mechanisms for their formation. 

Polyphosphazene Random and Block Copolymers with Alko t alko] and Trifluoroethoxy Side Groups... 

In order to study the gener ty of this method, it was desirable to synthesize a number of other phosphoranimines. Additionally, it was of interest to utilize these monomers to produce random copolymers by crosspropagation and block copolymers by the addition of the second monomer ter conversion of the first so that die properties of these polymers could be systematically controlled. Although random copolymers have been synthesized by the thermal polymerization of phosphoranimines (7) and by the ring opening polymerization method, (4) polyphosphazene AB block copolymers have not been previously reported. 

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