Access to Metastable Gel States Using Seeded Self-Assembly of Low-Molecular-Weight Gelators

Abstract

Here we report on how metastable supramolecular gels can be formed through seeded self-assembly of multicomponent gelators. Hydrazone-based gelators decorated with non-ionic and anionic groups are formed in situ from hydrazide and aldehyde building blocks, and lead through multiple self-sorting processes to the formation of heterogeneous gels approaching thermodynamic equilibrium. Interestingly, the addition of seeds composing of oligomers of gelators bypasses the self-sorting processes and accelerates the self-assembly along a kinetically favored pathway, resulting in homogeneous gels of which the network morphologies and gel stiffness are markedly different from the thermodynamically more stable gel products. Importantly, over time, these metastable homogeneous gel networks are capable of converting into the thermodynamically more stable state. This seeding-driven formation of out-of-equilibrium supramolecular structures is expected to serve as a simple approach towards functional materials with pathway-dependent properties.

Keywords: gels; low-molecular-weight gelators; out-of-equilibrium systems; seeded self-assembly; supramolecular chemistry.