Design of tough hydrogels maintaining structural integrity under multivariable mechanical loads remains hugely challenging because the anticipated characteristics such as stretchability, strength, toughness, and fracture resistance can hardly be compatible. Herein, a simple but robust hydrogel network formed by copolymerization of divinyl benzene with acrylamide in micellar solutions for ultra‐high fracture resistance and self‐recoverable stretchability is proposed. The network provides dynamic association of hydrophobic domains and homogeneous crosslinking of hydrophilic chains, which shows step‐by‐step deformation process. The dynamic associations allow recoverable small deformations, then the homogeneous crosslinking ensures reversible unfolding and alignment of polymer chains to self‐strengthen for ultra‐large deformations without crack propagations. The resultant hydrogels exhibit comprehensive unbreakable feature with self‐recoverable ultra‐high stretchability (100% recovery from 10 200% strain), superior fracture resistance (toughness > 26 kJ m−2), and anticrack propagation and fatigue (fatigue threshold: ≈2.5 kJ m−2). Even the prenotched hydrogels can undergo tens cyclic loads at 10 200% strain and thousands cyclic loads at 200% strain without noticeable changes in mechanical performance. The robust network prepared from homogeneous hydrophobic crosslinking provides a facile approach and a new mechanism to explore tough hydrogels with superior antifracture and extreme self‐recoverable deformability for diverse applications.

In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.

Exploring a simple, on-demanding method of manipulating ionic conduction of ionic liquids with large amplitudes is a challenging task. Here, a reversible ion-conducting switch was obtained based on photoswitchable sol−gel transitions. The device was successfully applied in an electronic circuit to switch it on/off. The ion gel was prepared by directly mixing following individual components: azobenzene (Azo), poly(Nisopropylacrylamide) (PNIPAm), and. The framework of this gel structure was particularly designed as an analogue to the physical mode of control theory: sensor/amplification/action. Light-induced isomerization of Azo acts as the light sensor to trigger the macroscopic sol−gel transition of PNIPAm assemblies. Such transition works as the amplification, which significantly affects the ionic movements, resulting in high-amplitude switching behavior. A photoswitchable ionic conductive device was demonstrated as action in this paper. Under UV irradiation, the sol-like state of Azo/PNIPAm/[C 2 mim][NTf 2 ] provided a higher ion conduction (around 1 mS/cm) while being exposed to visible light, and a lower ion conduction (0.04 mS/cm) was observed in the gel state. This photoswitchable ion conductivity device was integrated to a well-designed logic gate to switch circuits on or off. This confirms the possible practical application of the sol−gel device, which outputs stable and detectable electrical signals.The research here demonstrates a simple but effective strategy to control the ionic movements, which can be applied in optoelectronic devices. The principle can be used to design different types of molecular optoelectronic switches.

A side chain liquid crystal polymer containing pendant sulfonic acid groups has been synthesized by post-polymerization functionalization of a brominated mesogenic precursor. A macroscopic alignment was achieved by mechanical shearing of the liquid crystal polymer in the smectic phase. The uniaxial layered assembly exhibited anisotropic proton conductivities under anhydrous conditions and has potential applications in medium temperature fuel cells.Scheme 1 Synthesis of the mesogenic P2 containing sulfonic acid groups.

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