Degradable poly phosphazene

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... 

Diffusion of solutions of Cr, Co and Mn ions through a PTFE membrane allows for separation of Cr from the remaining ions. Thermal stability of polymeric materials is a significant consideration in many poly(phosphazene) applications. The kinetics of the thermal degradation of PTFE are best fit with a model requiring a two step initiation for depolymerization. These steps involve formation of defect units, such as =P(0)NH- and =P(0)N(CH2CFj)-, which become active centers for depolymerization. Mixed... 

Amino, alkoxy, and aryloxy polyphosphazenes are typically prepared by nucleophilic displacement reactions of poly(dihalophosphazenes). Analogous reactions with organometallic reagents, however, result in chain degradation and cross linking rather than in linear, alkyl, or aryl substituted poly(phosphazenes). The thermolysis of appropriate silicon-nitrogen-phosphorus compounds can be used to prepare fully P—C bonded poly(organophosphazenes). The synthesis of two of these materials and their Si—N—P precursors is described here. 

In vitro evaluations have been made. Bioerodible poly(phosphazenes) have the advantage that the degradation products are biocompatible. The majority of bioerodible poly(phosphazenes) have been synthesized by the classical thermal procedure of Allcock et al. (1965)—reference (15). The copolymer in question is described. In vivo performances in clinically relevant conditions are planned for PPHOS matrices. 

Thermal degradation poly(tri-fluoroethoxy-phosphazene) (homopolymers)... 

Figure 2.4 Some water-soluble, degradable poly(organo) phosphazenes...

Figure 3.13 Schematic representation of a covalently bound, degradable poly(organo)phosphazene drug conjugate...

---