Metal–ligand induced supramolecular polymerization: A route to responsive materials

Abstract

The use of metal-ligand binding as the driving force for the self-assembly polymerizations of a ditopic ligand offers a facile route to the preparation of organic/inorganic hybrid materials. Such metallo-supramolecular polymers potentially offer the functionality of the metal ion along with the processibility of a polymer. We report, herein, the preparation of gel-like metallo-supramolecular polymers prepared from a monomer unit, which consists of a 2,6-bis-(benzimidazolyl)-4-hydroxypyridine unit attached to either end of a polyether chain, mixed with a lanthanoid metal (e.g. La(III), Eu(III)) and a transition metal ion (e.g. Co(II) or Zn(II)). Such materials show dramatic reversible responses to a variety of stimuli, including thermal, mechanical, chemical and light. The nature of the response can be controlled by the nature of the combination of transition metal ion and lanthanoid metal ion used.

Linear shear and nonlinear extensional rheology of unentangled supramolecular side-chain polymers

“…The ability to vary and control the interactions in supramolecular systems provides an efficient tool to tune the structure, dynamics and rheology [26,29,46].…”

“…Supramolecular polymers are made of covalent chains connected through reversible interactions, such as hydrogen bonding , metal-ligand coordination [26][27][28][29][30][31][32][33][34][35][36][37][38], and ionic aggregation [39][40][41][42][43][44][45]. The ability to vary and control the interactions in supramolecular systems provides an efficient tool to tune the structure, dynamics and rheology [26,29,46].…”

Rheology of a reversible supramolecular polymer studied by comparison of the effects of temperature and chain stoppers

“…The ability to adapt their chain length makes supramolecular polymers promising candidates for applications in responsive materials. [8][9][10][11] Such applications require that the equilibration ͑caused by the breaking and reformation of bonds͒ be sufficiently fast, so a change in conditions is translated into a measurable change in the material properties within a practically relevant time. For systems which satisfy both criteria ͑noncovalent bonds between monomers and sufficiently fast equilibration͒ the term "reversible supramolecular polymers" is used.…”

Mechanochemistry in Polymers with Supramolecular Mechanophores

“…A broad range of stimuli-responsive metallopolymers based on Mebip-terminated macromonomer-metal ion interactions has in the meantime been investigated, not only with respect to the mechanical activation of the weak links, but also in terms kinetic formation of the metal-ligand complex, [80] influence of the metal centers (dynamic vs. inert, two-vs. three functional, variation of optical properties) and polymer backbones (e.g. polar vs. nonpolar, rubbery vs. glassy vs. semicrystalline).…”