Supramolecular gels and mesoscopic structure

From the perspective of mesoscale, the formation mechanism of crystal network structure of supramolecular gel, the influence of structure on macroscopic properties, and the design and control of supramolecular gels are reviewed. Crystal network is a key character of the hierarchical structure of the gel, the formations of the basic and multi-level crystal networks are based on the crystal nucleation and growth. The engineering and controlling of the gel structure can be implemented by various stimuli, such as additives, sonication, seeding and thermodynamic driving force, which leads to a controllable performance of the gel. In addition, the methods of characterizing supramolecular gels are systematically summarized, such as rheology, atomic force microscope, scanning tunnel microscope, scanning electron microscope, transmission electron microscope, polarizing optical microscope, X-ray diffraction (XRD), small-angle X-ray scattering, small angle neutron scattering, nuclear magnetic resonance spectroscopy, dynamic light scattering (DLS), etc. Supramolecular gel performance is determined by the hierarchy mesoscopic structures, which can significantly improve the properties of the material. Four factors can be correlated to the structure and performance of material: topology, correlation length, symmetry/ordering and strength of association of crystal networks. According to the more in-depth understanding of mesoscopic supramolecular gels, the research and development of such a material will be pushed to a new stage.