Kakehashi Rie, Tokai Naoji, Nakagawa Makoto, Kawasaki Kazunori, Horiuchi Shin, Yamamoto Atsushi
Surfactant Laboratory, Osaka Research Institute of Industrial Science and Technology, Osaka 536-8553, Japan.
Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda 563-8577, Japan.
Gels. 2023 Mar 22;9(3):261. doi: 10.3390/gels9030261.
Rheology control is an important issue in many industrial products such as cosmetics and paints. Recently, low-molecular-weight compounds have attracted considerable attention as thickeners/gelators for various solvents; however, there is still a significant need for molecular design guidelines for industrial applications. Amidoamine oxides (AAOs), which are long-chain alkylamine oxides with three amide groups, are surfactants that act as hydrogelators. Here, we show the relationship between the length of methylene chains at four different locations of AAOs, the aggregate structure, the gelation temperature , and the viscoelasticity of the formed hydrogels. As seen from the results of electron microscopic observations, the aggregate structure (ribbon-like or rod-like) can be controlled by changing the length of methylene chain in the hydrophobic part, the length of methylene chain between the amide and amine oxide groups, and the lengths of methylene chains between amide groups. Furthermore, hydrogels consisting of rod-like aggregates showed significantly higher viscoelasticity than those consisting of ribbon-like aggregates. In other words, it was shown that the gel viscoelasticity could be controlled by changing the methylene chain lengths at four different locations of the AAO.
流变学控制在许多工业产品中都是一个重要问题，如化妆品和涂料。最近，低分子量化合物作为各种溶剂的增稠剂/胶凝剂受到了相当大的关注；然而，工业应用的分子设计指南仍然有很大需求。酰胺基氧化胺（AAOs）是具有三个酰胺基的长链烷基氧化胺，是一种可作为水凝胶剂的表面活性剂。在此，我们展示了AAOs四个不同位置的亚甲基链长度、聚集体结构、凝胶化温度以及所形成水凝胶的粘弹性之间的关系。从电子显微镜观察结果可以看出，通过改变疏水部分的亚甲基链长度、酰胺基和氧化胺基团之间的亚甲基链长度以及酰胺基之间的亚甲基链长度，可以控制聚集体结构（带状或棒状）。此外，由棒状聚集体组成的水凝胶显示出比由带状聚集体组成的水凝胶显著更高的粘弹性。换句话说，结果表明通过改变AAO四个不同位置的亚甲基链长度可以控制凝胶的粘弹性。
