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首页> 外文期刊>RSC Advances >Synthesis of novel cyclosiloxane monomers containing push–pull moieties and their anionic ring opening polymerization
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Synthesis of novel cyclosiloxane monomers containing push–pull moieties and their anionic ring opening polymerization

机译：含推挽结构的新型环硅氧烷单体的合成及其阴离子开环聚合

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The synthesis of three novel tetracyclosiloxane monomers modified either with a nitroaniline (NA) or with a Disperse Red 1 (DR1) push–pull group and their ring opening polymerization reaction in the presence of tetramethylammonium hydroxide are presented. The prepared monomers and polymers were characterized by different spectral methods and gel permeation chromatography. For the crystalline monomers, the structures were further proven by single crystal X-ray diffraction. Dynamic scanning calorimetry shows that the polymers that carry NA groups have a glass transition temperature ( T _(g) ) well below room temperature (RT), while the one that carries DR1 groups melts at 55 °C. The transition temperatures have a strong effect on permittivity as indicated by broadband impedance spectroscopy measurements conducted at different temperatures and frequencies. The polymers modified with NA groups have a high permittivity (maximum value of 17.3) at RT, suggesting the polar groups to be mobile and orientation polarization to be effective. However, the polar groups of the polymer modified with DR1 are frozen and thus cannot contribute to the permittivity via orientation polarization. Consequently, the permittivity is only 8.8 at RT, but increases to 22 above the melting temperature, where the dipoles are mobile. Because of the high dielectric permittivity and rather low T _(g) , the polymers modified with NA are attractive as active dielectric materials in actuators, capacitors, and stretchable electronics, whereas the polymer modified with DR1 may be of interest in nonlinear optical devices.
机译：介绍了用硝基苯胺（NA）或分散红1（DR1）推挽基团修饰的三种新型四环硅氧烷单体的合成及其在氢氧化四甲铵存在下的开环聚合反应。通过不同的光谱方法和凝胶渗透色谱法对制备的单体和聚合物进行了表征。对于结晶单体，通过单晶X射线衍射进一步证实了结构。动态扫描量热法显示，带有NA基团的聚合物的玻璃化转变温度（T_（g））大大低于室温（RT），而带有DR1基团的聚合物在55°C时熔化。如在不同温度和频率下进行的宽带阻抗谱测量表明，转变温度对介电常数有很大影响。用NA基团改性的聚合物在室温下具有很高的介电常数（最大值为17.3），这表明极性基团是可移动的，取向极化是有效的。但是，用DR1改性的聚合物的极性基团被冻结，因此不能通过取向极化贡献介电常数。因此，在室温下介电常数仅为8.8，但在偶极子可移动的熔化温度之上增加到22。由于介电常数高且T_（g）较低，因此用NA改性的聚合物作为致动器，电容器和可拉伸电子产品中的活性介电材料具有吸引力，而用DR1改性的聚合物可能在非线性光学器件中引起人们的兴趣。

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