Continuous Spinning of High‐Tough Hydrogel Fibers for Flexible Electronics by Using Regional Heterogeneous Polymerization

Abstract

Hydrogel fibers have attracted substantial interest for application in flexible electronics due to their ionic conductivity, high specific surface area, and ease of constructing multidimensional structures. However, universal continuous spinning methods for hydrogel fibers are yet lacking. Based on the hydrophobic mold induced regional heterogeneous polymerization, a universal self‐lubricating spinning (SLS) strategy for the continuous fabrication of hydrogel fibers from monomers is developed. The universality of the SLS strategy is demonstrated by the successful spinning of 10 vinyl monomer‐based hydrogel fibers. Benefiting from the universality of the SLS strategy, the SLS strategy can be combined with pre‐gel design and post‐treatment toughening to prepare highly entangled polyacrylamide (PAM) and ionic crosslinked poly(acrylamide‐co‐acrylic acid)/Fe3+ (W‐PAMAA/Fe3+) hydrogel fibers, respectively. In particular, the W‐PAMAA/Fe3+ hydrogel fiber exhibited excellent mechanical properties (tensile stress > 4 MPa, tensile strain > 400%) even after 120 days of swelling in the pH of 3–9. Furthermore, owing to the excellent multi‐faceted performance and one‐dimensionality of W‐PAMAA/Fe3+ hydrogel fibers, flexible sensors with different dimensions and functions can be constructed bottom‐up, including the one‐dimensional (1D) strain sensor, two‐dimensional (2D) direction sensor, three‐dimensional (3D) pressure sensor, and underwater communication sensor to present the great potential of hydrogel fibers in flexible electronics.

Spider-silk-inspired strong and tough hydrogel fibers with anti-freezing and water retention properties

“…3f-h). The toughness of the S-PAZr was higher than that of most current hydrogel fibers and well those of anhydrous polymers such as polydimethylsiloxane (PDMS), Kevlar, and synthetic rubber, even exceeding the toughness of natural tendon and spider silk 11,18,25,36,[53][54][55][56][57][58] .…”

“…Therefore, a BSE strategy was proposed to adjust the non-covalent interactions of polymers through inorganic salts. To successfully implement the corresponding bionic design, we employed an improved self-lubricating spinning strategy, which allowed us to freely design the hydrogel fiber network structure for the continuous fabrication of bionic hydrogel fibers 36 . For demonstration, the Hoffmeister effect-sensitive PVA and ion-coordinatable PAA were chosen as a model system.…”

Flexible Multimodal Magnetoresistive Sensors Based on Alginate/Poly(vinyl alcohol) Foam with Stimulus Discriminability for Soft Electronics Using Machine Learning

“…The optical and SEM images of the SPG foam at different magnifications are displayed in Figure 2a−c. Due to the low density of 0.219 g/ cm 3 , a typical SPG foam can be easily placed on a flower petal. In addition, the cross-sectional morphologies exhibit obvious three-dimensional porous structures, in which the pores are evenly dispersed without obvious aggregation and the size distribution is relatively uniform, which provides a stable skeleton with a smooth surface for the distribution of bidisperse MPs.…”

“…Nowadays, flexible sensors have attracted increasing attention in soft electronics applications due to their high flexibility, favorable stretchability, easy wearability, and unique electrical responsiveness. − However, it remains an enormous challenge for flexible sensors to be simultaneously integrated with multimodal stimuli-responsiveness, high sensitivity, quick response time, reliable stability, and good biocompatibility. − Multimodal flexible sensors are capable of detecting various types of stimuli, including strain, stress, temperature, magnetic fields, gases, pH, etc. − For example, an electronic skin with biomechanical and bioelectrical signal-sensing functions, a paper-based sensor with touch trajectory and pressure recognition, as well as an artificial peripheral neural system with exteroceptive and artificial proprioceptive sensors . Compared with other sensing modes, the magnetic sensors have gradually shown high potential for the fields of remote human–machine interaction (HMI), underwater equipment, and intelligent robotics due to their superior characteristics of precise remote controllability, quick response, strong penetrating power, and environmental adaptability. − …”

Bilayer Hydrogel Actuators with High Mechanical Properties and Programmable Actuation via the Synergy of Double-Network and Synchronized Ultraviolet Polymerization Strategies

“…Hydrogels are soft polymeric materials with a three-dimensional network structure formed through the chemical or physical crosslinking of monomers/polymers [ 1 , 2 , 3 , 4 , 5 ]. By introducing stimulus-responsive monomers into a hydrogel network, hydrogels can respond to external stimuli (light, temperature, pH, etc.)…”