Poly carbophosphazene s

The six-membered heterocyclic ring, cyclocarbophosphazene, [(NPCl2)2CCl] serves as the precursor for poly(carbophosphazene)s. The pentachlorocyclocarbophosphazene N3P2CCI5 can be considered as a hybrid of cyanuric chloride, N3C3CI3 and hexachlorocyclotriphosphazene, N3P3CI6. Thus, while cyanuric chloride has three carbons and the hexachlorocyclotriphosphazene has three phosphorus atoms, the cyclocarbophosphazene has one carbon and two phosphorus atoms (Fig. 5.3) [4, 5]. 

HsCO iV OCHs NaOCH, NaOCHaCFs CF3CH20 OCH2CF3 

The pentachlorocyclocarbophosphazene, [(NPCl2)2CCl], has been found to undergo ROP at 120 °C to afford poly(chlorocarbophosphazene), [(NPCl2)2CCl] (see Eq. 5.1) [4,5]. 

The polymer [(NPC iCClJn is hydrolytically sensitive and rapidly reacts with moisture with concomitant chain degradation. Its P-NMR spectrum consists of a single resonance observed -3.7 ppm. This is upfield 

The chlorine substituents of poly(chlorocarbophosphazene) can be replaced with other nucleophiles to afford poly(organocarbophosphazene)s which are hydrolytically more stable in comparison to the parent polymer (Fig. 5.7). There are no examples of poly(alkyl/arylcarbophosphazene)s. The molecular weights of poly(organocarbophosphazene)s are moderately high (Mv, = 50,000-150,000). 

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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). 

Poly(heterophosphazene)s whose backbones comprise phosphoms, nitrogen, and another element - carbon or sulfur -were also synthesized. " In poly(carbophosphazene)s (poly-114), every third phosphoms atom is replaced by carbon. Poly-114 obtained in the thermal polymerization of a cyclic carbophosphazene was further transformed into white, solid, hydrolytically stable poly((aryloxy)carbophosphazene) (stmcture 115 Af -lO ). The polymer backbone in stmcture 115 was less flexible than in classical polyphosphazenes. The reaction of poly-114 with alkylamines was also studied. Poly (carbophosphazene) s have higher glass transition temperatures than their classical polyphosphazene counterparts with the same side groups. The increased stiffness of the carbophosphazene backbone is attributed to the high torsional barrier of the organic C = N n-bonds compared to the low barrier of the P = N n-bonds. ... 

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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