Chain phosphazene copolymers

As the synthetic approach to polydichlorophosphazene put forward by R. De Jaeger has been already described in several recent review articles [10,38,57, 172], in this paper we will illustrate only the polycondensation approach proposed by I. Manners and H. R. Allcock, together with the consequences of this reaction on the preparation of chain phosphazene copolymers (block copolymers) [220,223,224,232-234,240], and star polymers [222]. 

In the same scheme, moreover, it is evident that, besides phosphazene homopolymers, the substitution of the chlorines with two (or more) different substituents leads to the preparation of substituent phosphazene copolymers [263] containing different homosubstituted and heterosubstituted monomeric units. Moreover, the cationic polymerization of phosphoranimines [215-217] produces polymers with hving reactive ends (vide supra) from which the preparation of chain phosphazene copolymers (block copolymers) [220,223,225, 229,232-235,239, 240] formed by different polymeric backbones linked together in a unique macromolecule could be obtained. 

The possibility, through living cationic polymerization processes, to produce linear chain phosphazene copolymers [486]... 

JThe effect of the substituent on the properties of the polyphosphazenes is not fully understood. For instance, [NP(OCH ) ]n and [NP C CH. homopolymers are elastomers (8,29). Synthesis using lithium, in contrast to sodium, salts is claimed to produce rubber-like fluoroalkoxyphosphazene polymers (30). The presence of unreacted chlorine or low molecular weight oligomers can affect the bulk properties (31,32). Studies with phosphazene copolymers both in solution and in the bulk state (29,33-38) indicate a rather complex structure, which points out the need for additional work on the chain structure and morphology of these polymers. 

The presence in these copolymers of hetero-substituted monomeric units randomly dispersed along the phosphazene skeleton brings about the extreme difficulty of the polymeric chains to be packed in regular structures. They lose, therefore, the original stereo-regularity of the parent phosphazene homopolymers (microcrystalline materials), and show only amorphous structures, with sharp decrease in the values of the Tg (collapsed up to about -90 °C) and with the onset of remarkable elastomeric properties [399,409,457]. 

Graft copolymer, polyclhylene-gra/f-poly(propylcnc oxide) (PE-g-PPG), has been synthesized by ring opening anionic polymerization of propylene oxide with a phosphazene catalyst and hydroxylated polyethylene (Mn = 12400, [OH] = 5 units/chain). Polymerization of propylene oxide was carried out in tetraline at 120 °C for 20 hours. The 13C NMR analysis of PE-g-PPG suggested that all the hydroxyl groups were consumed for propylene oxide polymerization (Fig. 6). 

Polyl(trifluoroethoxy)(octafiuoro pentoxy)]phosphazene decomposes thermally by random chain scission. The decomposition process has been studied in detail for polyKbis trifluoroethoxy) phosphazene] using n.m.r., i.r. spectroscopy, gas chromotography, mass spectrometry, and electron spectroscopy for chemical analysis. Random chain scission is confirmed followed by depolymerization with an average zip length of 35 chain units. The thermo-oxidation of a hydroquinone-phosphorus oxychloride copolymer has also been investigated. Decomposition is a two-stage process, chain scission to form quinone followed by oxidation of the quinone to maleic anhydride. ... 

Nonfluorinated ionomer membranes Numerous different types of nonfluori-nated ionomer membranes, among them ionomer membranes based on styrene polymers and copolymers containing polystyrene units [7], arylene main-chain polymers of different poly(phenylene) [8], poly(ethersulfone) [9-11], poly(etherketone) [12-15], poly(phenylene oxide) [16,17], poly(phenylene sulfide) [18] types, and such membranes based on an inorganic backbone like poly(phosphazenes) [19,20], poly(siloxane)s [21], have been developed in the past years... 

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