噻吩基CNTs分散剂及其在增强SiO2复合气凝胶中的应用

Thiophene-based dispersant for CNTs and its application in silica composite aerogels

  • 摘要: 二氧化硅(SiO2)气凝胶具有高孔隙率、高化学稳定性等特点,但力学强度差极大地制约了其实际应用。基于此,本文采用碳纳米管(CNTs)掺杂的方法制备了CNTs/SiO2复合气凝胶,有效提高了其力学强度。合成了一种噻吩基芳香型两亲分子(DSiTE),利用其表面活性实现了CNTs在水中的高浓度分散。CNTs分散液与前驱体溶胶可均匀混合,经碱催化凝胶、常压干燥,制备出了一系列不同CNTs质量分数的复合气凝胶。研究了水解时间、CNTs含量等因素对气凝胶力学性能的影响。结果表明,两亲分子含有的硅羟基可参与到凝胶骨架的形成中,极大地改善了CNTs与SiO2的界面相容性,无分相情况出现。在水解时间为2 h,CNTs质量分数为0.18% 的条件下,CNTs/SiO2气凝胶的抗压强度可达0.93 MPa,是纯气凝胶的1.98倍。本研究采用的分散-复合一体化策略为制备高力学强度SiO2气凝胶提供了一种新颖有效的思路。。

     

    Abstract: silica (SiO2) aerogel has the advantages of high porosity and good chemical stability, but its practical application is greatly restricted by poor mechanical strength. Based on this, CNTs/SiO2 composite aerogels were prepared by doping carbon nanotubes (CNTs), which exhibited distinctively enhanced mechanical strength. A thiophene-based aromatic amphiphilic molecule (DSiTE) was synthesized and used to achieve high-concentration aqueous CNTs dispersion. It can be uniformly mixed with SiO2 sol, and a series of composite aerogels with different CNTs mass fractions were prepared by alkali catalyzed gel and atmospheric drying. The effects of hydrolysis time and CNTs content on the mechanical properties were studied. The results show that the Si-OH groups of the amphiphilic molecule can participate in the formation of aerogel skeleton, greatly improving the interfacial compatibility between CNTs and SiO2, without phase separation. Under hydrolysis of 2 h and CNTs mass fraction of 0.18 wt%, the compressive strength of CNTs/SiO2 aerogel reached 0.93 MPa, which is 1.98 times that of pure SiO2 aerogel. The integration strategy of this study provides a novel and effective approach for preparing SiO2 aerogels with good mechanical strength.

     

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