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Scrolling of supramolecular lamellae in the hierarchical self-assembly of fibrous gels

DOI: 10.1016/j.chempr.2017.09.001 DOI Help

Authors: Christopher D. Jones (Durham University) , Stuart R. Kennedy (Durham University) , Martin Walker (Durham University) , Dmitry S. Yufit (Durham University) , Jonathan W. Steed (Durham University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chem , VOL 3 , PAGES 603 - 628

State: Published (Approved)
Published: October 2017
Diamond Proposal Number(s): 8682

Abstract: Lamellar supramolecular assemblies are a common feature of fibrous gels formed by molecules such as peptides and ureas. Competition between gelation and crystallization is highly solvent dependent and can be governed by the dynamics of nascent lamellae in solution. We hypothesize that gel fibrils are formed when the scrolling of lamellae outpaces multilayer stacking. Crystallographic data on model picolyl bis(urea)s were correlated with their gelation properties. Most structures are lamellar, and gels involving fibrous aggregates form concomitantly alongside crystalline solvates. A distinguishing feature of these solvate crystals is that the lamellae have unequal numbers of picolyl groups on opposite faces. Atomistic molecular dynamics simulations show that this asymmetry causes isolated lamellae to scroll spontaneously into fibrils, whereas symmetrical lamellae adopt flat, crumpled, or saddle-like morphologies. Scrolling represents a general mechanism for gel formation, affording networks of unbranched fibers with monodisperse diameters dictated by the equilibrium curvature of the folding lamellae.

Journal Keywords: gel; supramolecular; hierarchical; lamellar; self-assembly; scrolling

Subject Areas: Chemistry, Materials

Instruments: I19-Small Molecule Single Crystal Diffraction