Influence of solvents on properties of monolithic La-based aerogels
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摘要: 采用溶胶-凝胶工艺,以氯化镧(LaCl37H2O)为前驱体,以甲醇和乙醇为溶剂,聚丙烯酸为分散剂,环氧丙烷为凝胶促进剂,分别合成两种性能不同的稀土La基气凝胶。采用扫描电子显微镜、傅里叶红外光谱仪、比表面积与孔径分析仪、力学性能测试仪对不同溶剂制备的两种稀土La基气凝胶的微观结构、成分、比表面积、孔径分布和力学性能进行了研究表征。结果表明,以甲醇和乙醇为溶剂制备的稀土La基气凝胶都具有纳米多孔材料的典型特征,由大量nm量级的球形和长条形颗粒胶连而成,孔洞结构丰富。以乙醇为溶剂制备的稀土La基气凝胶的网络骨架更纤细,孔洞更大,比表面积达到220 m2g-1,密度约为160 mgcm-3,但力学性能较差。而以甲醇为溶剂制备的稀土La基气凝胶的网络骨架更强壮,孔洞更小,比表面积达到95 m2g-1,密度约为350 mgcm-3,力学性能较好。样品性能上的差异可能是由甲醇的极性比乙醇的极性强引起的。Abstract: La-based aerogels were synthesized by using LaCl37H2O as precursor, methanol and ethanol as solvents, via sol-gel process. The microstructure, components, specific surface area, pore diameter distribution and mechanical properties were characterized by scanning electron microscopy, Fourier transform infrared spectrometer, adsorption/desorption analysis and mechanical property tester, respectively. The results reveals that La-based aerogels derived from methanol and ethanol have a three-dimension network that consists of interconnected bead-like particles with diameters varying from several tens to hundreds nanometer. Comparing to the aerogel (specific surface area: 95 m2g-1, density: about 350 mgcm-3) derived from methanol, the aerogel (specific surface area: 220 m2g-1, density: about 160 mgcm-3) derived from ethanol possesses better pore morphology and worse mechanical property. The properties of the La-based aerogels can be attributed to the stronger polarity of methanol.
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Key words:
- rare earth /
- lanthanum /
- aerogel /
- sol-gel /
- mechanical property
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