Poly thionylphosphazenes

A third variant on the polyphosphazene skeletal structure is represented by the poly(thionylphosphazenes) (reactions (65) and (66)) in which every third phosphorus along the chain is replaced by a sulfur VI atom.266-272 These species are more hydrolytically stable than their sulfur IV analogues, probably because the presence of two side groups on sulfur provides additional protection for the main chain. 

Molecular dynamics calculations have been carried out to simulate a conformational model and vibrational spectra of poly(dichlorophospha-zenes). Molecular dynamics similations for [NP(OCH2CF3)2] and the isomers [NP(OBu")2] , [NP(OBu )2] and [NP(OBu )2] show a reasonable agreement between the calculated and experimental values of density and glass transition temperature as well as for gas transport parameters in these polymers.Small molecule models have been used for a theoretical approach of poly(thionylphosphazenes). ... 

In 1991, Liang and Manners reported that when the cyclic thionylphosphazene 18 is heated in the melt at 165°C, thermal ROP takes place to yield the poly-thionylphosphazene 19 with chlorine substituents at both sulfur and phosphorus [23] ... 

PROPERTIES OF SPECIAL INTEREST Film-forming elastomers, potential oxygen sensors for biomedical and aerospace are among this class of poly(thionylphosphazenes) depending upon substituents present. ... 

SYNTHESIS Poly[(M-butylamino)thionylphosphazene] can be prepared via the amino lysis of the chlorinated poly(thionylphosphazene) with butylamine. The chlorinated poly(thionylphosphazene) is synthesized via the thermal ring opening polymeriztion (ROP) of the corresponding cyclic thionylphosphazene... 

As mentioned earlier the glass transition temperatures of poly(thionylphosphazene)s indicate that these are polymers with a flexible backbone. These polymers have five side-groups per repeat unit which is similar to poly(carbophosphazene)s and poly(thiophosphazene)s. On the other hand, a comparable polyphosphazene unit has six side-chains. This has interesting consequences on the glass transition temperatures of poly(thionylphosphazene)s (Table 5.3). 

Fig. 5.17. Synthesis of poly(thionylphosphazene)s containing alkyl side-groups...

In 1991, another class of sulfiir-nitrogen-phosphorus polymers, poly-thionylphosphazenes, were reported (96,97). These materials, which possess four-coordinate sulfuifVI) atoms in the backbone, possess improved stability and were prepared by a thermal ROP of cyclic thionylphosphazenes (30), with either chlorine or fluorine at the sulfuifVI) center, at 165-180°C (eq. 27) (98). An... 

Ambient temperature polymerization of structure 119 in methylene chloride and with GaCls, AICI3, or SbCls as initiators was also reported. Apart from the high molar mass poly(thionylphosphazene) [(NSOCl)(NPCl2)2]m IT-, 18-, 24-, and higher-membered macrocycles were formed. GaCls is the most effective initiator and AICI3 the least one. ... 

A further variant of this preparative protocol involves the synthesis of polymers that contain phosphorus, nitrogen, and a third element in the main chain. For example, we have recently prepared the first poly(carbophosphazenes) and poly(thiophosphazenes) via the chemistry shown in Schemes III and IV (9, 10), Manners has reported the synthesis of poly(thionylphosphazenes) using the same approach (11),... 

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