Stearic acid or eicosanoic acid mixed with di- or oligomeric amines in specific molar ratios form stable gels in water. The formation of such hydrogels depends on the hydrophobicity of the fatty acid, and also on the type of amine used. The gelation properties of these two-component systems were investigated using electron microscopy, FTIR spectroscopy, 1H NMR spectroscopy, differential scanning calorimetry (DSC), and both single-crystal and cast-film X-ray diffraction. Results of FTIR spectral analysis suggest salt formation during gelation. 1H NMR analysis of the gels indicates that the fatty acid chains are immobilized in the gel state and when the gel melts, these chains regain their mobility. Analysis of DSC data indicates that increase in the spacer length in the di-/oligomeric amine lowers the gel-melting temperature. Two of these gelator salts developed into crystals and structural details of such systems could be secured by single-crystal X-ray diffraction analysis. The structural information of the salts thus obtained was compared with the XRD data of the self-supporting films of those gels. Such analyses provided pertinent structural insight into the supramolecular interactions that prevail within these gelator assemblies. Analysis of the crystal structure confirmed that multilayered lamellar aggregates exist in the gel and it also showed that the three-dimensional ordering observed in the crystalline phase is retained in only one direction in the gel state. Finally, the hydrogel was used as a medium for the synthesis of silver nanoparticles. The nanoparticles were found to position themselves on the fibers and produced a long, ordered assembly of gel-nanoparticle composite.

Directing self-assembly processes out-of-equilibrium to yield kinetically trapped materials with well-defined dimensions remains a considerable challenge. Kinetically controlled assembly of self-synthesizing peptide-functionalized macrocycles through a nucleation-growth mechanism is reported. Spontaneous fiber formation in this system is effectively shut down as most of the material is diverted into metastable non-assembling trimeric and tetrameric macrocycles. However, upon adding seeds to this mixture, well-defined fibers with controllable lengths and narrow polydispersities are obtained. This seeded growth strategy also allows access to supramolecular triblock copolymers. The resulting noncovalent assemblies can be further stabilized through covalent capture. Taken together, these results show that self-synthesizing materials, through their interplay between dynamic covalent bonds and noncovalent interactions, are uniquely suited for out-of-equilibrium self-assembly.

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Multiple, coexisting hydrophobic compartments have been created in water using molecular self-sorting among mixtures of bolaamphiphiles with differently spaced urea groups in their hydrophobic parts. The selective incorporation of bisurea functionalized fluorescent probes showed that different bolaamphiphiles form separate populations of rod-like micelles, which dynamically coexist in solution, each micelle binding to its correspondingly functionalized guests.