Poly thiophosphazene s

An important reaction that revealed that the S-Cl bond in N3P2SCI5 ean be heterolytieally cleaved has been carried out by Roesky [10]. Thus, the reaction of N3P2SCI5 with SbCls affords [N3P2SCl4] [SbCl6] (see Eq. 5.2). The crystal structure of [N3P2SCl4] [SbCl6] revealed that it has a planar 

The conversion of N3P2SCI5 to its cation implied that ROP can be utilized for its conversion to a linear polymer. This promise was realized much later by the work of Allcock and coworkers [8, 9]. Accordingly, it was found that N3P2SCI5 undergoes a ROP at 90 °C to afford poly(thiophosphazene), [(NPCl2)2(NSCl)]n (see Eq. 5.3). 

The P-NMR spectrum of the polythiophosphazene, [(NPCl2)2(NSCl)] , shows a single resonance at 8 = -4.6. The chemical shift of the polymer is about 30 ppm upfield shifted in comparison to the six-membered ring. 

Also the presence of a single resonance indieates a predominantly head-tail arrangement as in the case of the poly(carbophosphazene) (Fig. 5.10). 

The chlorine atoms in the polymer [(NPCl2)2(NSCl)]n can be readily replaced by nucleophiles such as phenoxide or / -phenyl phenoxide. However, unlike [NP(OPh)2]n, [ NP(OPh)2 2S(OPh)]n is not hydrolytically as stable. This has been attributed to the inherent reactivity of S(IV) centers. Further, reaction of [(NPCl2)2(NSCl)]n with substituted phenols such as 2-phenylphenol or 3-phenylphenol do not afford fully substituted polymers. However, these polymers [N3P2S(OC6H4-w-C6H5)4,4(Cl)o.6] and 

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P-NMR data and Tg data for some selected poly(thiophosphazene)s are summarized in Table 5.2. The polymer [(NPCl2)2(NSCl)]n has a Tg of -40 °C. Thus, in comparison with [NPCyn the glass transition temperature of... 

The P-NMR data of poly(thiophosphazene)s indicate that the trends observed are similar to those foimd in polyphosphazenes. Thus, while [(NPCl2)2(NSCl)]n shows a resonance at -4.6 ppm, replacing the chlorines by biphenyloxy substituents shifts the P resonance upfield (Table 5.2). 

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). 

Hydrogels and amphiphilic membranes Poly(carbophosphazenes) and poly(thiophosphazenes) New condensation syntheses NLO and high refractive index polymers Microencapsulation of mammalian cells (PCPP) Polyphosphazene polymer blends and IPN s Borazine derivatives Poly(phosphazophosphazenes)... 

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