Processable and Luminescent Supramolecular Hydrogels from Complex Coacervation of Polycations with Lanthanide Coordination Polyanions

Abstract

Luminescent supramolecular gels based on dynamic lanthanide coordination can be of profound interest in optical and sensing applications. However, most of the current lanthanide-based gels suffer from their poor mechanical strength and processability for practical uses. Here, we develop an effective strategy to fabricate a multifunctional robust luminescent hydrogel via the ionic coacervation of an anionic lanthanide coordination polymer with a cationic polyelectrolyte. The resultant hydrogels turn out to be moldable, self-healable, recyclable, and may be regarded as a new kind of "luminescent plastic". Owing to the unique force-induced plastic deformation, long fibers can be directly drawn from the hydrogel reservoir at room temperature. Moreover, the dynamic nature of such a physical polymer network leads to multiple responses to various stimuli, such as temperature, salt, and sonication. The studies described herein not only enable the easy processability of luminescent hydrogels, but also provide a new strategy to prepare stimuli-responsive and self-healing lanthanide-based hydrogels as sustainable and smart materials.

Adaptive Ionogel Paint from Room‐Temperature Autonomous Polymerization of α‐Thioctic Acid for Stretchable and Healable Electronics

“…The Arrhenius plot calculated the apparent activation energy ( E a ) of the ionogel to be 73.5 kJ mol −1 , which is much smaller than the dissociation energy of covalent bonds ( E a ≈ 350 kJ mol −1 ). [ 48 ] Such a small activation energy arising from totally non‐covalent interactions allows for the rapid self‐healing of polyTA ionogel, important for coating applications. As presented in Figure 3f, placing polyTA ionogel at 55 °C (above the transition temperature of 52 °C to thermally activate dimeric H‐bonds) for 4 h can basically repair the damages as indicated by the disappearance of scars.…”

Response of metal-coordination-based polyelectrolyte complex micelles to added ligands and metals

“…16 Moreover, introducing metal ions not only provides novel functional properties, e.g., magnetic and fluorescence properties from lanthanides, but also introduces probes for investigating the internal structure using, e.g., the optical spectrum and fluorescence life time. [17][18][19][20] More importantly, we find that these micelles do not have a narrow range of preferred composition: an excess of coordination complexes in solution cannot undo the coacervation needed for micellization, because the supramolecular polyelectrolytes are reversible structures that predominantly form inside the micellar core. 21 This behavior is totally different for polyelectrolyte micelles in which the corepolyelectrolyte consists of normal polymers, and an excess or shortage of that with respect to the second (block copolymer) polyelectrolyte will destabilize the micellar structure.…”

Multicolor Fluorescent Polymeric Hydrogels

“…By applying a similar strategy, Wang et al. recently reported supramolecular polyelectrolyte complex hydrogels that were formed through electrostatic interactions between the anionic lanthanide coordination polymers and the cationic poly(3‐(methacryloylamino)propyltrimethylammonium chloride) (PMPTC) [24c] . As shown in Figure 5 C, the fluorescent lanthanide‐coordinated polymers were prepared from the bis‐ligand L 2 EO 4 , which bears two dipicolinic acid (DPA) moieties and thus can coordinate with Eu 3+ or Tb 3+ in a molar ratio of 3:2.…”