Study Of Molecular Design, Synthesis, Mechanism Of Polyphosphazenes Elastomers

Polyphosphazenes are hybrid inorganic-organic high polymers comprised of a backbond of alternating phosphorus and nitrogen atoms with two (organic or inorganic) side groups linked to each phosphoru. Polyphosphazenes has been applied in many fields, such as elastomers, biodegradable or degradation of medical materials, flame retardants, solid polymer electrolyte membranes and photoelectric materials, attribute to the multifarious of side groups. Elastomers are soft materials, with low temperature resistance and thermal stability, which play a major role in engineering and biomedicine and has been researched as hot-topic always. Furthermore, only after the chains have been cross-linked do the true elastomeric properties appear.Some kinds of linear-polyphosphazenes were obtained by substitution reaction of PDCP with the sodium salts. The molecular structure of polymer was characterized by IR and NMR. The glass transition temperature and thermal stability were investigated by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of these polymers were also analyzed by static mechanic analysis. Moreover, we has been researched the molecular structure of side groups influence on solubility and morphology of linear-polyphosphazenes. The data analysis indicate that the flexibility and entanglement of side groups will affect the glass transition temperature and thermal stability of linear-polyphosphazenes; the polarity and entanglement of side groups will affect the solubility and morphology of linear-polyphosphazenes.In addition, some kinds of curable-polyphosphazene were obtained by chemically induced covalent cross-linking. The method of experiment is that the substitution reaction of PDCP with single sodium salts of ethylene-glycol and the network structure will appear without cross-linking agents when the giycol hydroxyl form ether-bond at 120℃.The molecular structure of polymer was characterized by IR and NMR. The glass transition temperature and thermal stability were investigated by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of these polymers were also analyzed by static mechanic analysis. The data indicate that the curable-polyphosphazenes had low glass transition temperature, good thermal stability and high tensile strength.