Spontaneous Orthogonal Self‐Assembly of a Synergetic Gelator System

Abstract

Dedicated to ngel Guti rrez Ravelo on the occasion of his 68th birthday ACHTUNGTRENNUNG(Organo)gel materials have been exhaustively developed over the past two decades, however the recent interest for advanced functional nanomaterials has made this area of research particularly exciting. Organogels based on low molecular weight organic gelators (LMWOGs) are formed by self-assembled fibrillar networks (SAFINs), which are produced by a combination of weak non-covalent physical interactions including hydrogen bonding, p–p stacking, dipole–dipole or donor–acceptor interactions, metal coordination and van der Waals interactions. Gels based on strong chemical bonds cannot be redissolved and consequently, they do not show thermoreversible gel–sol transitions. The enhancement of the mechanical strength and thermostabilities of the gels has therefore become crucial for numerous applications in the area of material science. In view of some of the applications of gelator systems, we recently became interested in organic non-covalent interpenetrating polymer network (IPN) materials, more specifically, in the investigation of 3D organogel networks and their effects on the physico-chemical properties in the systems. Different groups have reported various examples of these innovative materials, which are synthesised under suitable conditions and characterised by a special network structure consisting of two types of morphologies of different physico-chemical nature. Van Esch and co-workers have recently reported that hydrogelators could undergo an orthogonal, independent selfassembly process in the presence of micellar and vesicular aggregates, with the subsequent coexistence of gel fibres within the formed nanostructures. Herein, we report the potential of two gelator systems (with different solvent-dependent abilities) to gel by self-assembly processes and their ability to spontaneously self-organise and simultaneously assemble into a novel nanomaterial containing two different interconnected porous and fibre-type domains. The final nanomaterial can remarkably improve the properties of related or similarly generated independent organogels. The multi-gelator gels comprise two different types of aggregates, which are spontaneously and simultaneously assembled. With this purpose, we employed a mixture of two different organogelators 1 and 2. Firstly, organogelator 1 is a synergistic multi-component organogelator liquid system, in which the gelation phenomenon of oxygenated solvents takes place at low temperature (after gentle heating of the isotropic solution). Organogelator 2 is an oligoamide, which exclusively produces stable organogels in chlorinated solvents upon cooling of the gently heated isotropic solution. The organogel properties of both gelator systems (1 and 2) have been reported previously.