Hydrogels and organogels, as two crucial representatives of soft materials, have attracted immense interest. However, they develop independently along two parallel lines, and these gels with single networks have their inherent drawbacks. For example, hydrogels tend to freeze, and organogels are usually brittle. Herein, organogels were incorporated into a hydrogel matrix for the synthesis of organohydrogels GOHs through polymerization in Pickering emulsion. The rigid organogel domains contribute to enhancing the strength of organohydrogels. Besides this, the organogels derived from 12-HAS self-assembly behavior exhibit a gel–sol transition when the temperature reaches 70 °C, thus leading to a thermo-softening behavior in the GOHs. Due to the phase transition of organogel domains and the elastic hydrogel network, the resultant organohydrogels demonstrate high-strain shape-memory performance (over 1000%) which could help achieve full recovery in seconds. Consequently, GOHs are endowed with the potential of practical application in soft robots, wearable devices, and biological materials.
Ya Liu,Yaqi Ren,Jing Huang,Hongsheng Lu,Zhiyu Huang,Li Wang
Shape-memory gel materials are widely used in smart drives and biological tissues due to their excellent flexibility and diverse stimuli responsiveness. In particular, shape-memory organohydrogel materials have rose intense interest recently owing to their sophisticated shape memory behavior. However, conventional mechanical enhancement strategies, either by introducing nanoparticles or double-network structure, employed in the preparation of organohydrogels require high energy input, leading to difficulties in emulsification for emulsion precursors of organohydrogels. These strategies are not suitable for large-scale production of high-strength organohydrogels. Herein，a high-strength shape-memory organohydrogel NL-H was prepared based on dual hydrogen bonding and gelator-induced solidification effect. The precursor was easily emulsified, as the aqueous phase involved no nanoparticles or highly viscous polymers. Moreover, the dual hydrogen bonds among the dual amide groups of N -acryloyl glycinamide (NAGA) monomers can endow the organohydrogel with high mechanical properties . Owing to the oil-solidification effect of gelator HSA, the mechanical properties could be greatly enhanced, showing a high Young's modulus of 188.04 kPa. Furthermore, by integrating a high elastic hydrogel matrix and reversible oil domains, the organohydrogel showed a thermo-softening and favorable shape-memory properties. Consequently, this work provides a new enhancement strategy for the preparation of organohydrogel with high mechanical properties and excellent shape memory capabilities. And the simple preparation process can also facilitate the large-scale fabrication.
Fat mimics are one of the most common substitutes for animal fats in processed foods. However, basing on high internal phase Pickering emulsion (HIPPEs) gel imitate adipose tissue to achieve the desired strength and elastic, while the formation and stabilization mechanism are barely understood. Here, we proposed a strategy to fabricate rigid-flexible double network using κ-carrageenan (CA) and bacterial cellulose (BC), in oder to improve the mechanical performance of HIPPEs gel. The effects of different ratios of CA/BC (2:1, 4:1, 8:1) and K + addition on the properties of HIPPEs-CA/BC gels were investigated. Results showed that HIPPEs-CA/BC 8:1 & K + exhibited better rheological, textural, oil holding capacity and organoleptic properties. Thermal softening behavior of HIPPEs-CA/BC 8:1 & K + was similar to the pork adipose tissue. The microstructure of gel demonstrated that HIPPEs-CA/BC 8:1 & K + was featured with honeycomb-like pore and network walls, which in turn comprise interpenetrated double network structures. Meanwhile, it showed an ultrahigh stress, high Young's modulus and good cyclic compress behavior. Additionally, the hydrogen bonds and K + -cross-linked were proved to play crucial roles in facilitating the formation of a stable and elastic CA/BC matrix. This study establishes structure-performance mechanisms in strongly and elastically structured HIPPEs gels, providing an advanced strategy for developing HIPPEs gel with promising applications in adipose tissue substitutes.
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