Strong Physical Hydrogels from Fibrillar Supramolecular Assemblies of Poly(ethylene glycol) Functionalized Hexaphenylbenzenes

Abstract

Gel formation without chemical cross-links requires strong physical bonds, as observed in diverse molecular and macromolecular systems or supramolecular assemblies above a critical concentration. Here, we present a new molecular amphiphile of propeller-like hexaphenylbenzene derivative bearing two short poly­(ethylene glycol) (PEG) chains which forms reversible physical gels comprising long (∼2.2 μm) bundles of hydrogel fibrils in coexistence with spherical micelles. Combination of topological (entanglement-like) interactions between the fibers and specific hydrophobic interactions due to the helicity of the PEG chains is proposed to account for the hydrogelation in the semidilute regime. The present supramolecular hydrogels, which are based on small molecules, exhibit extraordinary properties with an exceptionally strong dependence of the shear modulus on concentration, akin to the behavior of ultrahigh molecular weight cellulose-based fibers.

Cross‐Linking Dynamics of Cellulose Nanofibrils‐Based Transient Network Hydrogels: A Study of pH Dependence

“…Consider the elasticity measurement during approach of the AFM tip can be regarded as mechanical response of undisturbed gel network, the higher cross‐linking density require the greater force for deformation of more rigid gels. Thus, the above results collectively corroborate that the ionic cross‐links between CNF/PEG‐NH 2 not only enhance the mechanical properties of gels as a whole but also suggest different mechanical dynamics of their fibrous components . It also should be noted that the modulus data determined by nanoindentation and rheology have the same tendency but different absolute values.…”

“…Thus, the above results collectively corroborate that the ionic cross-links between CNF/PEG-NH 2 not only enhance the mechanical properties of gels as a whole but also suggest different mechanical dynamics of their fibrous components. [27] It also should be noted that the modulus data determined by nanoindentation and rheology have the same tendency but different absolute values. This discrepancy may stem from the different frequency and loading direction applied for the measurements, where the loading direction on the samples are along with compression molding direction and perpendicular to the compression molding direction for indentation and tensile test, respectively.…”

Bisurea-Functionalized RAFT Agent: A Straightforward and Versatile Tool toward the Preparation of Supramolecular Cylindrical Nanostructures in Water

“…In most of the studies, low molar mass polymers were used, in particular oligo(ethylene glycol)s, and their functionalization by the sticker units was achieved by post-polymerization strategies. [19][20][21][22] Considering the time-consuming processes necessary to prepare these polymers and purify them from unmodified counterparts, more straightforward and versatile synthetic strategies are highly desirable.…”

Sugar‐Based Self‐Assembly of Hydrogel Nanotubes Manifesting ESIPT: Theoretical Insight and Application in Live Cell Imaging

“…The frequency dependency (Figure (b)) of the G′ for BTHBC hydrogel is determined in the angular frequency range of 1to100 rad/s. Here, G′ is substantially higher than G′′, indicating its elastic nature rather than its viscous property –. The greater value of G′ than the G′′ within the linear viscoelastic region makes BTHBC a ‘‘strong gel” …”