title: Mechanical properties of self-assembled Fmoc-diphenylalanine molecular gels.
abstract: We explore the phase diagram and mechanical properties of molecular gels produced from mixing water with a dimethyl sulfoxide (DMSO) solution of the aromatic dipeptide derivative fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF). Highly soluble in DMSO, Fmoc-FF assembles into fibrous networks that form gels upon addition of water. At high water concentrations, rigid gels can be formed at Fmoc-FF concentrations as low as 0.01 wt %. The conditions are established defining the Fmoc-FF and water concentrations at which gels are formed. Below the gel boundary, the solutions are clear and colorless and have long-term stability. Above the gel boundary, gels are formed with increasing rapidity with increasing water or Fmoc-FF concentrations. A systematic characterization of the effect of Fmoc-FF and water concentrations on the mechanical properties of the gels is presented, demonstrating that the elastic behavior of the gels follows a specific, robust scaling with Fmoc-FF volume fraction. Furthermore, we characterize the kinetics of gelation and demonstrate that these gels are reversible in the sense that they can be disrupted mechanically and rebuild strength over time.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, 191 Roger Adams Lab, Urbana, Illinois 61801, United States.
authors.forename: Nikola A
authors.initials: NA
authors.lastname: Dudukovic
authors.forename: Charles F
authors.initials: CF
authors.lastname: Zukoski
mesh_terms: D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004151:Dipeptides; D005449:Fluorenes / Q000737:chemistry; D005782:Gels / Q000737:chemistry*; D015394:Molecular Structure; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D004151:Dipeptides; D005449:Fluorenes; D005782:Gels; C026650:phenylalanylphenylalanine; D010649:Phenylalanine; D004121:Dimethyl Sulfoxide