Programming Stress Relaxation and Creep in Low-Molecular-Weight Self-Assembled Hydrogels Through Polymer...

Mechanical property characterization of supramolecular viscoelastic materials, particularly low-molecular-weight gelator (LMWG)-derived hydrogels, has predominantly relied on small-amplitude oscillatory shear (SAOS) measurements, although these experiments probe network dynamics only at short timescales and fail to capture the full spectrum of network rearrangements that drive bulk mechanical behavior. A key challenge is unveiling how transient non-covalent interactions in LMWGs and covalent polymeric components collectively modulate viscoelasticity across multiple timescales. Herein, we investigate an LMWG-polymer hybrid hydrogel to demonstrate how the progressive integration of a covalent polymer into a self-assembled network regulates the bulk mechanical response, using short-timescale SAOS and long-timescale stress-relaxation and creep/creep-recovery experiments. Notably, frequency-sweep and stress-relaxation measurements reveal that the storage modulus and characteristic relaxation time exhibit distinct sensitivities to polymer concentration, with comparable stiffnesses occurring alongside noticeably different relaxation times in the intermediate polymer composition range. Creep/Creep-recovery measurements further show enhanced resistance to irreversible deformation and improved elastic recovery at low polymer loadings, whereas higher polymer concentrations primarily promote faster recovery dynamics through a transition from dual to single retardation behavior. These findings demonstrate that polymer incorporation can differentially modulate the stiffness and relaxation dynamics of LMWG-derived supramolecular networks, providing a framework for tuning viscoelastic behavior across multiple timescales.