Toughening Hydrogels with Fibrillar Connected Double Networks

Compared to conventional gels, eutectogels encompassing deep eutectic solvents (DESs) circumvent the shortboards including poor temperature resistance, high cost, and undesired toxicity. However, existing eutectogels suffer weak intra‐ and interchain interactions, which culminates in vanishing autofluorescence, weak mechanic and feeble adhesion. Although myriad strategies have been proposed to boost the polymer/polymer interactions within gels, the processes are time‐consuming, which are not suitable for mass production or emergent deployment. Herein, to deal with it, a facile solvation chemistry is leveraged to build dynamic rigid network via incorporating active polymer backbones and DESs. Within these eutectogels, DESs play a magnet‐like role, and physically cluster polymer chains together via multiple noncovalent forces, thus intensifying polymer/polymer and DESs/polymer interactions. This solvation network bestows rare autofluorescence and unprecedentedly high strength, toughness, and adhesion among reported analogues, even in harsh conditions. Moreover, the mechanism of solvation chemistry is fully scrutinized for the first time. It is believed that this facile strategy can be easily expanded to the orchestrations of other soft materials.

Solvation Chemistry Enables Eutectogels with Ultrahigh Autofluorescence, Toughness, and Adhesion under Extreme Environments

Jiang,

Hou,

Wang

et al. 2024

Continuous Preparation of the Record Strength and Toughness Hydrogel Fibers with a Homogeneous Crosslinked Network by Microcrystalline Dispersed Growth

Zhou,

Chen,

Han

et al. 2024

Homogeneous crosslinked networks can achieve a balance between the strength and toughness of various biological materials, yet continuous synthesis of such networks remains challenging. Here, a strategy involving microcrystal dispersed growth to continuously fabricate hydrogel fibers with a homogeneous crosslinked network through wet spinning is reported. Rapid phase separation induced by solvent exchange under dense entanglement results in a uniform microcrystalline crosslinked network. Salting‐out induced crystal growth within the densified structure, while orientation and structural densification are achieved with the presence of a sacrificial salt template. Through the integration of nucleation, growth, and orientation, the homogeneous crosslinked network is constructed within the hydrogel matrix. Therefore, the strongest hydrogel fiber so far, which also exhibits a range of tunable properties, including strength (0.32 –141.66 MPa) and toughness (0.43 –157.93 MJ m⁻3) across a high‐water content range (40.6% to 86.8%) is reported. This design approach provided a viable strategy for the continuous preparation of ultra‐strong and tough hydrogels with a homogeneous crosslinked network.

Super Strong and Tough Hydrogels Constructed via Network Uniformization of Macromolecular Chains

Xu,

Tan,

Dong

et al. 2024

The characteristic of materials with special strength and toughness is distinguished by the uniform arrangement of their multi‐level structures, which is a key factor that significantly affects their mechanical behavior and overall performance. This work explores the challenges and potential solutions to enhance the mechanical properties of hydrogels through the construction of multi‐scale, multi‐layered ordered uniform structures. A novel approach termed macromolecular network uniformization (MNU) that utilizes rotation ice templates to freeze‐cast uniform polymer networks in hydrogels is proposed. By integrating this process with salt‐out densification, hydrogels with exceptional toughness exceeding 350 MJ m⁻3 in both x and y directions with super‐high tensile stress (20 MPa) and strain at break (3000%), are obtained. This research effectively addresses the inherent limitation of hydrogel materials, which are primarily composed of hydrophilic polymers, limiting their potential for functional diversity and enhanced performance. To overcome this, the expansion of the hydrogel matrix is demonstrated to include hydrophobic polymers such as polycaprolactone (PCL) and polyacrylonitrile (PAN), thanks to the high solubility of DMSO. The MNU technique effectively produces high‐performance hydrogels with enhanced mechanical properties, increasing substrate diversity and enabling the development of durable hydrogel materials for various applications.