Super Stretchable and Compressible Hydrogels Inspired by Hook-and-Loop Fasteners

Recent advances and perspectives on intercalation layered compounds part 1: design and applications in the field of energy

Herein, initially, we present a general overview of the global financial support for chemistry devoted to materials science, specifically intercalation layered compounds (ILCs). Subsequently, the strategies to synthesise these host structures and the corresponding guest-host hybrid assemblies are exemplified on the basis of some families of materials, including pillared clays (PILCs), porous clay heterostructures (PCHs), zirconium phosphate (ZrP), layered double hydroxides (LDHs), graphite intercalation compounds (GICs), graphene-based materials, and MXenes. Additionally, a non-exhaustive survey on their possible application in the field of energy through electrochemical storage, mostly as electrode materials but also as electrolyte additives, is presented, including lithium technologies based on lithium ion batteries (LIBs), and beyond LiBs with a focus on possible alternatives such XIBs (X = Na (NIB), K (KIB), Al (AIB), Zn (ZIB), and Cl (CIB)), reversible Mg batteries (RMBs), dual-ion batteries (DIBs), Zn-air and Zn-sulphur batteries and supercapacitors as well as their relevance in other fields related to (opto)electronics. This selective panorama should help readers better understand the reason why ILCs are expected to meet the challenge of tomorrow as electrode materials.

Antifreezing, Antidrying, and Conductive Hydrogels for Electronic Skin Applications at Ultralow Temperatures

Although conductive hydrogel-based flexible electronic devices have superb flexibility and high conductivities, they tend to malfunction in dry or frigid areas. Herein, an ultralow-temperature tolerant, antidrying, and conductive composite hydrogel is designed for electronic skin applications on the basis of the synergy of double-cross-linked polymer networks, Hofmeister effect, and electrostatic interaction and fabricated by in situ free radical polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid and acrylic acid in the presence of poly(vinyl alcohol) and conductive MXene sheets, followed by impregnation with LiCl. Thanks to the synergy of LiCl and the charged polar terminal groups of the synthesized polymers, the composite hydrogel can not only bear an ultralow temperature of -80 °C without freezing but also maintain its original mass. Meanwhile, the resultant hydrogel possesses satisfactory self-regeneration ability benefiting from the moisturizing effect of LiCl. The conductive network of MXene sheets greatly improves the ionic conductivity of the hydrogel at low temperatures, exhibiting an ionic conductivity of 1.4 S m-1 at -80 °C. Furthermore, the electronic skin assembled by the multifunctional hydrogel is efficient in monitoring human motions at -80 °C. The antifreezing and antidrying features along with favorable ionic conductivity, high tensile strength, and outstanding flexibility make the composite hydrogel promising for applications in frigid and dry regions.

Hydrothermal synthesis of layered zirconium phosphates and their intercalation properties

Layered inorganic materials are widely used as fillers in nanocomposites due to their unique properties such as mechanical performance, thermal properties, flame resistance, barrier properties, corrosion resistance, catalytic activity, and multifunctionality. Among them, layered α-zirconium phosphate (α-ZrP: Zr(HPO4)2H2O) is one of the representative inorganic materials and unique properties with P-O-H groups that can exchange inorganic and organic cations and intercalate basic molecules. This paper deals with the use of this compound as an adsorbent for heavy metal cations in wastewater. Samples were prepared by hydrothermal treatment at various Zr/P ratio, water amounts, and temperatures. Furthermore, an attempt was made to widen the interlayer distance of the sample using n-butylamine. The α- zirconium phosphate prepared at 160°C for 20 h with Zr/P = 1/2 adsorbed the most amount of metal ions. Furthermore, interlayer amine modification was effective. Then, the behaviour of the adsorption process was observed by varying the time of adsorption from 1 h to 50 h, in order to clarify the change in adsorption of the samples over time.

Covalently surface-grafting α‑zirconium phosphate nanoplatelets enables collagen fiber matrix with ultraviolet barrier, antibacterial, and flame-retardant properties

Manipulating the dispersibility and reactivity of two-dimensional nanomaterials in collagen fibers (CFs) matrix has aroused attention in the fabrication of multifunctional collagen-based nanocomposites. Here, α‑zirconium phosphate nanoplatelets (ZrP NPs) were surface-functionalized with gallic acid (GA) to afford ZrP-GA NPs for engineering CFs matrix. The influence of ZrP-GA NPs on the ultraviolet barrier, antibacterial, and flame-retardant properties of resultant CFs matrix were investigated. Microstructural analysis revealed that ZrP-GA NPs were dispersed and bound within the collagen fibrils and onto the collagen strands in the CFs matrix. The resultant CFs matrix also maintained typical D-periodic structures of collagen fibrils and native branching and interwoven structures of CFs networks with increased porosity and enhanced ultraviolet barrier properties. Inhibition zone testing presented excellent antibacterial activities of the CFs matrix owing to surface grafting of antibacterial GA. Thanks to enhanced dispersion and binding of ZrP NPs with the CFs matrix by surface-functionalization with GA, the resultant CFs matrix reduced the peak heat release rate and the total heat release by 42.9 % and 39.0 %, respectively, highlighting improved flame-retardant properties. We envision that two-dimensional nanomaterials possess great potential in developing reasonable collagen-based nanocomposites towards the manufacture of emergent multifunctional collagen fibers-based wearable electronics.

Tailoring the Growth of Nanosized α-Zirconium Phosphate

Nanosized α-zirconium phosphate (α-ZrP), unlike microcrystalline α-ZrP, takes less time to prepare and is synthesized directly in organic solvents. During the synthesis of nanosized α-ZrP, the heating step is critical because during which the particle growth/aggregation is ongoing. In order to explore more details of this step, extra water molecules were intentionally introduced to the ethanol gel of nanosized α-ZrP so that the evaporation of the solvent was slowed. To heat the gels at 65 °C for different periods (1-6 days), one could control with ease the synthesized α-ZrP in size, from 63 to 155 nm, and in morphology, from amorphous to highly crystalline. Furthermore, the heating step also affects the intercalated solvent and the dangling propionate groups on the edge of the nanosized α-ZrP, which could be deduced from the intercalation/exfoliation behavior of the nanocrystals. This modified synthesis method of nanosized α-ZrP offers an alternate means to tune the size and morphology of the nanosized α-ZrP for broad applications.

Gelation Based on Host-Guest Interactions Induced by Multi-Functionalized Nanosheets

Host–guest interaction, being reversible and stimuli-responsive, is ideal to be applied to the design of hydrogels. We created a gelation system based on the host–guest interactions between the adamantyl groups and β-cyclodextrin (β-CD) polymer. N,N,N-trimethyl-1-adamantylammonium hydroxide (TriMAA) cations were attached to the pre-exfoliated α-zirconium phosphate (α-ZrP) nanosheets by ionic bonding through a displacement reaction with the exfoliating agents. The exfoliated α-ZrP nanosheets with adamantyl groups directly or indirectly attached to the surface act as reversible high-functionality crosslinkers within the β-CD polymer. The gelation occurred at a host-to-guest ratio of 1:10 or 1:5 at room temperature within minutes. The agents used to exfoliate α-ZrP can tailor the surface of the resultant α-ZrP nanosheets and the ionic strength of the system, which directly affects the further gelation results. Plus, the exfoliating agent cations may generate a host-and-guest interaction with the β-CD polymer as well. This gelation process without covalent bonding formation should help fellow researchers to better understand the gelation system and host–guest interactions.