Aqueous spinning of robust, self-healable, and crack-resistant hydrogel microfibers enabled by hydrogen bond nanoconfinement

Abstract

Robust damage-tolerant hydrogel fibers with high strength, crack resistance, and self-healing properties are indispensable for their long-term uses in soft machines and robots as load-bearing and actuating elements. However, current hydrogel fibers with inherent homogeneous structure are generally vulnerable to defects and cracks and thus local mechanical failure readily occurs across fiber normal. Here, inspired by spider spinning, we introduce a facile, energy-efficient aqueous pultrusion spinning process to continuously produce stiff yet extensible hydrogel microfibers at ambient conditions. The resulting microfibers are not only crack-insensitive but also rapidly heal the cracks in 30 s by moisture, owing to their structural nanoconfinement with hydrogen bond clusters embedded in an ionically complexed hygroscopic matrix. Moreover, the nanoconfined structure is highly energy-dissipating, moisture-sensitive but stable in water, leading to excellent damping and supercontraction properties. This work creates opportunities for the sustainable spinning of robust hydrogel-based fibrous materials towards diverse intelligent applications.

Polyrotaxane‐Based Functional Materials Enabled by Molecular Mobility and Conformational Transition†

“…The self‐healing properties of elastomers and gels are essential to improve the safety, extend service life, and enable multiple recycling of functional devices, especially in the field of wearable electronics. [ 96‐106 ] However, achieving high self‐healing performance, high toughness, and desirable tensile strength simultaneously remains difficult. Okumura and Ito synthesized early slide‐ ring gels, cross‐linking α‐CD molecules in different polyrotaxane chains with epichlorohydrin.…”

Confinement of Oligopeptides by Terminally Functionalized Polyisoprene to Improve Their Mechanical Strength, Creep Resistance, and Antifatigue Properties

“…Additionally, the internal aggregates of the β-sheet were partitioned into sizes of around 20 nm in the terminal phase. It shows a potential enhancement of nanoconfinement effect. , …”

“…It shows a potential enhancement of nanoconfinement effect. 21,22 The formation of new terminal phases was investigated by attenuated total reflection fluorescence transformed infrared spectroscopy (ATR-IR), shown in Figure 1f. Obvious stretching vibrations of hydroxyl groups were observed in V-B-OH and V-R-OH at 3410 cm −1 , expect for V-PIP.…”

“…In this paper, we propose a succinct strategy called terminal nanoconfinement − to introduce a β-sheet into a hydroxylated terminal block noncovalently, where the polar terminal chains interact with and confine the β-sheet to tens of nanometers, therefore allowing the reversible breaking and reforming of hydrogen bond aggregates and limiting the hysteresis at the same time. This strategy allows the motion and assembly of oligopeptides in the polar phase of terminal hydroxyl groups, which is quite different from the previously reported covalent attaching method .…”

Stretchable, Low-Hysteresis, and Recyclable Ionogel by Ionic Liquid Catalyst and Mixed Ionic Liquid-Induced Phase Separation

“…For these as-prepared ionogels with the special sea-island phase separation structure, the crack will be pinned and blunted by high-energy hard PVA domains via the stress transfer and deformation (Figure S10). – Moreover, due to the differences between the hard and soft phases, more energy is required to enlarge the crack propagation zone from the soft IL-rich regions to the hard PVA domains. Thus, these ionogels also show excellent insensitivity toward crack propagation, and the notched 5%-ionogel-2 sample (notch root radius is 3 mm) can be stretched to 8 times its initial length (Figure j,k).…”