Nano-Materials and Processing Center, Korea Institute of Ceramic Eng. and Tech., 101 Soho-ro Jinju-si Gyeongsangnam-do, 52851, Korea.
J Nanosci Nanotechnol. 2020 Sep 1;20(9):5707-5710. doi: 10.1166/jnn.2020.17612.
The flexibility, pore structures and hydrophobicity could be controlled by changing TEOS/MTEOS ratio. A methyl functional group of MTEOS causes the difficulty of hydrolysis and condensation reactions, so that strong basic catalyst needs to be added for the gelation of MTEOS. Therefore, increasing of MTEOS ratio forms larger pore sizes and large primary particles with about one micrometer. MTEOS-based aerogels show the lowest specific area due to macropores with more than one thousand nanometers, although they are very flexible to elongate two times as long as their original sample length. For TEOS/MTEOS hybrid aerogels with 0.4-0.6 of TEOS ratio, they have the large specific surface area and pore volume, a little flexibility and hydrophobicity due to the remaining alkyl functional groups. This research presents the possibility of controlling flexibility, pore structures, hydrophobicity through hybridization of alkoxide and silane. It suggests a way of overcoming weaknesses of silica aerogels like brittleness and hydrophilicity.
通过改变 TEOS/MTEOS 的比例，可以控制其柔韧性、孔结构和疏水性。MTEOS 的甲基官能团导致水解和缩合反应困难，因此需要添加强碱催化剂才能使 MTEOS 凝胶化。因此，增加 MTEOS 的比例会形成更大的孔径和大约一微米的大初级颗粒。基于 MTEOS 的气凝胶由于具有超过一千纳米的大孔，因此比表面积最小，尽管它们非常柔韧，可以延长到原始样品长度的两倍。对于 TEOS/MTEOS 混合气凝胶，当 TEOS 与 MTEOS 的比例为 0.4-0.6 时，由于存在剩余的烷基官能团，它们具有较大的比表面积和孔体积、一定的柔韧性和疏水性。本研究通过烷氧基和硅烷的杂交，提出了控制柔韧性、孔结构和疏水性的可能性。它为克服二氧化硅气凝胶的脆性和亲水性等弱点提供了一种方法。
