偶氮聚电解质的合成及其pH敏感行为和热光性能研究

利用偶氮聚电解质上的羧基和偶氮生色基团的特性,研究了侧链偶氮聚电解质的pH值敏感性和热光性能.采用重氮-偶合反应方法合成了偶氮苯生色分子4-(4′-硝基苯基偶氮)苯酚,将生色分子、环氧氯丙烷和α-甲基丙烯酸通过自由基聚合法,合成了侧链偶氮聚电解质.利用傅里叶红外光谱(FTIR)、紫外-可见光谱(UV-V is)和核磁共振(1H-NMR)等分析手段对所合成的侧链偶氮聚电解质进行了结构表征.采用差示扫描量热分析仪(DSC)对偶氮聚电解质进行了热稳定性表征,其玻璃化转变温度(Tg)为189.8℃,表明具有较高的热稳定性.研究了不同pH值的偶氮聚电解质溶液的紫外-可见光谱,结果表明,偶氮聚电解质对pH值具有高度敏感性.采用衰减全反射(ATR)原理测量聚合物波导薄膜在650 nm和TM偏振下的折射率和热光系数dn/dT,其值为-1.92479×10-4℃-1,是无机材料如硅酸锌玻璃(5.5×10-6℃-1)和硼硅酸盐玻璃(4.1×10-6℃-1)的10倍以上,较有机材料聚苯乙烯(-1.23×10-4℃-1)和PMMA(-1.20×10-4℃-1)大.

PREPARATION, pH SENSITIVITY AND THERMO-OPTIC PROPERTIES OF AZO POLYELECTROLYTES

By using characteristics of carboxyl groups and azo chromophores,the pH sensitivity and thermooptic properties of the side-chain azo polyelectrolytes were studied.A chromophore molecule containing azobenzene,4-(4'-nitrophenylazo)phenol was synthesized from 4-nitroaniline,sodium nitrite and phenol via diazo-coupling reaction.A side-chain azo polyelectrolyte was obtained from the chromophore molecule,epoxy chloropropane and α-methacrylic acid by free radical polymerization.The chemical structures of azo polyelectrolytes were characterized by FTIR.UV-Vis spectroscopy and ~1H-NMR.The thermal properties were characterized using differential scanning calorimetry(DSC),and the glass transition temperature(T_g)189.8℃ showed that the azo polyelectrolyte had high thermal stability.Influences of different pH values on the UV-Vis absorption spectra of the azo polyelectrolyte were studied.The results showed that the UV-Vis absorption spectra of the azo polyelectrolyte changed with the pH value and the azo polyelectrolyte had high pHsensitivity.The measurements of refractive index (n) and thermo-optic coefficient (dn/dT) of the azo polyelectrolyte were demonstrated at 650 nm and TM mode by using the attenuated total reflection(ATR)technique.The thermo-optic coefficient (dn/dT) was-1.92479×10~(-4)℃~(-1),which was one order of magnitude larger than that of inorganic glasses such as zinc silicate glass(5.5×10~(-6)℃~(-1)),borosilicate glass (4.1×10~(-6)℃~(-1))and was larger than the organic material such as polystyrene(1.23×10~(-4)℃~(-1))and PMMA(1.20×10~(-4)℃~(-1)).These results indicate that the material may be provided to develop the new digital thermo-optic switch with low drive power.