Nissan Chemical Industries, Ltd. , Tokyo 101-0054 , Japan.
Langmuir. 2018 Jun 26;34(25):7503-7508. doi: 10.1021/acs.langmuir.8b00641. Epub 2018 Jun 14.
There has been a considerable interest in developing new types of gels based on a network of fibrous aggregate composed of low molecular weight gelators, also known as supramolecular gels (SMGs). Unlike conventional polymer gels with chemical cross-linking, the network formation in SMGs does not involve any covalent bonds. Thus, the network in SMGs has been often regarded as homogenous or less heterogeneous in comparison with that in chemically cross-linked polymer gels. In this study, we have experimentally verified the existence of the network heterogeneity even in SMGs. The thermal motion of probe particles in SMGs, which were prepared from aqueous dispersions of gelators having a different number of peptide residues, PalGH, PalGH, and PalGH, was tracked. The gels were spatially heterogeneous in terms of the network pore size, as evidenced by the variation in the particle motion depending on the location, at which a particle existed. With varying particle size, it was found that the characteristic length scale of the heterogeneity was in the order of (sub)micrometers and was smaller in the order of the PalGH, PalGH, and PalGH gels.
人们一直热衷于开发新型凝胶，这些凝胶基于由低分子量凝胶剂组成的纤维状聚集体网络，也称为超分子凝胶（SMG）。与具有化学交联的传统聚合物凝胶不同，SMG 中的网络形成不涉及任何共价键。因此，与化学交联聚合物凝胶相比，SMG 中的网络通常被认为是均匀的或异质程度较低的。在这项研究中，我们通过实验证实了即使在 SMG 中也存在网络异质性。跟踪了从具有不同数量肽残基的凝胶剂的水基分散体制备的 SMG 中探针粒子的热运动。根据粒子运动取决于其所处位置的变化，可以证明网络孔径在空间上是不均匀的。随着粒子尺寸的变化，发现异质性的特征长度尺度依次为（亚）微米级，并且按 PalGH、PalGH 和 PalGH 凝胶的顺序减小。
