Multifunction And Application Of Polyphosphazenes

The polyphosphazene is a kind of organic-inorganic polymer,which comprise of an extensive family of polymers built on a-[P=N]n-backbone owing to high reactivity which can be linked to wide range of side chains,leading to the products with a similarly diverse range of physical and chemical properties.A series of polyphosphazenes with excellent fluorescence properties were prepared by introducing different proportions β-naphthoxy into the chain of polyphosphazene,and properties of solution fluorescence,fluorescence of solid-state polymers,response to ions as well as degradability were studied.Relationship between glass transition temperature and contents of side group in polyphospazene chian was obtained through theoretical calculation and measure,which is useful in the synthesis of polyaryloxyphosphazene with a certain target Tg.Polyphosphazenes containing epoxy groups were prepared by a method of oxidation of carbon-carbon double bond,and curing performance of them was researched as well.By controlling the amount of β-naphthol and PDCP,we synthesized eight kinds of polyphosphazenes with substitution rate of 35%,42%,51%,60%,73%,82%,91%and 100%,respectively.The products were characterized by 31P-NMR and elemental analysis.The solvent effect indicated that the fluorescence intensity of polyphosphazenes is related to the concentration of solution and the excitation wavelength.The fluorescence intensity of the solution increased with increasing of concentration firstly,and then the fluorescence intensity of the solution decreased atλec=300nm;when the excitation wavelength is 355 nm,the fluorescence intensity of the polyphosphazene solution increased with the increase of concentration,but the overall fluorescence intensity is weaker than the fluorescence intensity at λex=300 nm.The effects of solvents showed that the fluorescence intensity of polyphosphazenes increased with increasing of polarity of the solvent except solvents with fluorescence property,which would enhance fluorescence intensity owing to the synergistic effect between polymers and solvent.These polyphosphazenes owned excellent solid-state fluorescence properties,and fluorescence intensity was stronger than that of solution state.The products can be made into a fluorescent powder and film.When the substitution ratio of β-naphthoxy was 91%,the polyphosphazene had the strongest fluorescence intensity in the eight polyphosphazene products in both the solid state and the solution.Additionally,its degradability was investigated,it was found that the degradation rate of polyphosphazene was affected by the side group substitution rate and the environmental pH value.When the side group substitution rate and the pH value of solution were lower,the degradation reaction of the product was carried out easily.The relationships between the content of side groups and glass transition temperature of polyphosphazene were obtained through experimental measurement,theoretical analysis and experimental verification.It found that a plot of the Tg vs.ethoxy contents yielded straight lines when polymer chain owned a higher substitution rate of phenoxy or ethoxy;when the ratio of the two groups in the polymer chain was higher,the contents of the structural unit B in the polyphosphazene chain had a great influence on the value of Tg.According to the quantitative relationship between Tg and side group content,a low temperature resistant polyaryloxyphosphazene with a glass transition temperature of-46.29℃ was synthesized successfully.It was found that the polyaryloxyphosphazene product has good vulcanization properties with the torque difference of 24.3 and T90 of 38 min.The mechanical properties test showd that the tensile strength was about 5 MPa.The preparation of polyphosphazene epoxy resin was carried out by nucleophilic substitution reaction of sodium salts and PDCP to obtain linear polyphosphazene containing carbon-carbon double bond,and oxidation of carbon-carbon double bond to gain epoxy group.The solid polyphosphazene epoxy resin and low molecular weight viscous polyphosphazene epoxy resin can be obtained by controlling molecular weight of PDCP.The synthesis method of polyphosphazene epoxy resin in this thesis was relatively simple without side reaction,which is beneficial to the purification of the product.The curing properties of polyphosphazene epoxy resin were preliminarily investigated by reaction with m-xylylenediamine.It was found that the curing reaction between the high molecular weight polyphosphazene epoxy resin and the curing agent was difficult to carry out relatively;while the low molecular weight polyphosphazene epoxy resin can be cured with the curing agent without solvent with poor strength.