Phosphate-pendant groups

Table 8.9 gives the cone data for flame retardant polystyrene nanocomposites (PS/OLP-clay) prepared using clay modified with an oligomeric phosphate ammonium salt (OLP) containing both ammonium salt and phosphate-pendant groups placed randomly along the polymer backbone. The HRR data for the... 

The resistance of polymers to flame may be increased by the addition of halogenated compounds and antimony oxide. Organic phosphate additives inhibit the glow of the char formed in burning polymers. Polymers with chlorine pendant groups, such as PVC, and those with halogen-substituted phenyl groups, such as polyesters produced from tetrabromophthalic anhydride, are more flame-resistant than hydrocarbon polymers. 

The degradation of the poly(phosphazenes) is very well understood, with the production of ethanol, phosphate, ammonium salts, and the pendant groups (Andrianov and Payne 1998). When the pendant group is an amino acid, all of the degradation... 

The L-N3 ligand has also been used to stabilize mononuclear [Mo O] complexes possessing pendant phosphate ester groups (42) and Mo "P distances of 4-8 A (80, 81). The NMR linewidths are strongly dependent upon the Mo—P distance, and reasonable Mo—P distances were derived from longitudinal relaxation times using the Solomon equation 154). Molecular modeling studies of Mo-co indicate that phosphate coordination to the Mo atom is stereochemically feasible, but the P ENDOR studies of the Mo(V) states of xanthine oxidase (67) estimate the Mo—P distance as 7-12 A and seem to rule out such a structure. 

The use of cyclophosphazene in the formulation of flame retardant materials has generated numerous patents. " Various known cyclo-matrices based on phosphazene bismaleimide or triazine and, especially, the styrene polymer (159) having cyclo-alkoxy or aryloxy-phosphazenes as pendant groups, have been found to be resistant to atomic oxygen, probably by the formation of a protecting layer of phosphate. " ... 

Heterochain (co)polymers with Choi pendant groups have been prepared by ROP. A cyclic phosphate monomer with Choi moiety (Fig. 8f) has been prepared and copolymerized with two other cyclic phosphate monomers followed by ATRP graft polymerization to introduce hydrophilic side chains [207]. The Choi moieties help this amphiphilic polyphosphate-based graft copolymer to form stable associations in water and to improve the encapsulation of anticancer drugs. 

Scheme 36 A plausible process of nucleotide activation using NCAs as energy carriers in an RNA world. For reasons of simplicity, the activation of a separate nucleotide is presented here, but many other alternative systems can be conceived as for example the reaction of a pendant phosphate at the 5 -terminus of an RNA oligomer. The structure of the oligomer may assist the reaction through neighboring group effects and favorable interactions with reactants...

Stoichiometric transesterification reactions in which the pendant hydro l group of La or [Eu(13)](CF3S03)3 is phosphoiylated, giving [Ln(23)](CF3S03)2, have been observed when bi8(4-nitrophenyl) phosphate or ethyl(4-nitrophenyl) phosphate are used as the substrate (39). The reaction is 10-fold faster when the more acidic Eu(III) ion is used. 

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