Y型偶氮旋光聚合物的合成及热光性能研究

Synthesis and study on thermo-optic property of Y-style azo optically active polymer

以对硝基苯胺、亚硝酸钠和苯胺为原料,采用重氮-偶合反应方法,合成有机生色分子:4-(4′-硝基-苯基二氮烯基)-苯胺(NABA)。以偶氮二异丁腈(AIBN)为引发剂,将NABA、手性试剂L-(-)-酒石酸、丙烯酰氯和甲基丙烯酸乙酯制备Y型偶氮旋光聚合物(PMEA)。利用傅里叶红外光谱和紫外-可见光谱等分析手段对所合成的NABA和PMEA进行了结构表征。采用示差扫描量热(DSC)和热失重分析(TG)对该聚合物的热稳定性进行了表征。DSC和TG结果显示,该聚合物的玻璃化转变温度为95.4℃,在5%的热失重温度为185℃,表明具有较好的热稳定性。测定了材料在不同温度的折射率(n)和热光系数(dn/dT);通过热光系数的测量,计算了聚合物的介电常数(ε)、介电热光系数(dε/dT)、体积热膨胀系数(β)和体积热膨胀系数变化率(dβ/dT)。该旋光聚合物材料的热光系数值为-3.031 43^-3.817 14×10-4℃-1,对研制新型热光开关具有一定的意义。

An organic chromophoric molecule,4-（4′-nitro-phenyl-diazenyl）-aniline（NABA）,was synthesized from 4-nitroaniline,sodium nitrite and aniline via diazo-coupling reaction.The Y-style azo optically active polymer（PMEA） was obtained from chromophoric NABA,chiral reagent L（-）-tartaric acid,acryloyl chloride,ethyl methacrylate,and azobisisobutyronitrile（AIBN）used as the initiator.The chemical structures of chromophores NABA and PMEA were characterized by FT-IR and UV-Vis spectroscopy.The differential scanning calorimetry（DSC） and thermogravimetric analysis（TG） results showed that the glass transition temperature（Tg） of polymer was 95.4 ℃,and the 5% weight loss temperature was 185 ℃,which showed that the polymer had good thermal stability.The measurements of refractive index（n） and thermo-optic coefficient（dn/dT） of PMEA were demonstrated at different temperatures.The values of n and dn/dT were used to calculate the dielectric constant（ε）,its variation with temperature（dε/dT）,the volume expansion coefficient（β）,and its variation with temperature（dβ/dT）.The thermo-optic coefficient was-3.031 43～-3.817 14×10-4 ℃-1.This conclusion has a certain significance for the development of novel thermo-optic switch.