Metal Ion-Induced Acid Hydrolysis Strategy for the One-Step Synthesis of Tough and Highly Transparent Hydrolyzed Polyacrylamide Hydrogels.

Polyacrylamide (PAM) hydrogel is hard to enhance through coordination bonds because amide groups rarely coordinate with metal ions strongly in an aqueous solution. It is known that the aqueous solution of ZrOCl.8HO can be strongly acidic depending on its concentration.

The Effect of Colloidal Nanoparticles on Phase Separation of Block and Heteroarm Star Copolymers Confined between Polymer Brushes.

The effect of colloidal nanoparticles on the phase changes of the amphiphilic AB linear diblock, AAB, and AB heteroarm star copolymers confined between two polymer brush substrates was investigated by using a real-space self-consistent field theory. By changing the concentrations of nanoparticles and polymer brushes, the phase structure of the amphiphilic AB copolymer transforms from lamellar to core-shell hexagonal phase to cylinder phase. The pattern of AB heteroarm star copolymer changes from core-shell hexagonal phases to lamellar phases and the layer decreases when increasing the density of the polymer brushes.

Highly Conductive Polysiloxane Elastomers with Excellent Transparency, Resilience, and Stretchability.

Flexible transparent conductive materials show great potential in wearable electronics, flexible sensors, and so on. But the most used flexible conductive materials like hydrogels and ionogels suffer from evaporation and solvent leakage. For the application in these fields, integrated performances of preeminent resilience, transparency, stability, and conductivity that do not change with deformation are prerequisites.

One-Step in Situ Synthesis of Tough and Highly Conductive Ionohydrogels with Water-Retentive and Antifreezing Properties.

Flexible and conductive gels are promising materials as intelligent and wearable electronics. Herein, through a facile one-step in situ free-radical polymerization, tough VSNPs-PAA-Zr ionohydrogels with integrated multiple functionalities are prepared, which are dually cross-linked by multivalent vinyl-functionalized silica nanoparticles (VSNPs) and metal coordination between Zr and the carboxyl groups in PAA chains. The incorporation of Zr with stable valency during polymerization enables the direct formation of a large number of metal coordination cross-links for adequate energy dissipation, overcoming the inhibition of unstable metal ions on the polymerization process.

Biomimetic Gradient Hydrogel Actuators with Ultrafast Thermo-Responsiveness and High Strength.

Most current hydrogel actuators suffer from either poor mechanical properties or limited responsiveness. Also, the widely used thermo-responsive poly-(-isopropylacrylamide) (PNIPAM) homopolymer hydrogels have a slow response rate. Thus, it remains a challenge to fabricate thermo-responsive hydrogel actuators with both excellent mechanical and responsive properties.

Super Tough and Intelligent Multibond Network Physical Hydrogels Facilitated by TiCT MXene Nanosheets.

Stretchable and conductive hydrogels have emerged as promising candidates for intelligent and flexible electronic devices. Herein, based on a multibond network (MBN) design rationale, super tough and highly stretchable nanocomposite physical hydrogels are prepared, where 2D TiCT MXene nanosheets serve as multifunctional cross-linkers and effective stress transfer centers. Further MXene-poly(acrylic acid) (PAA)-Fe MBN physical hydrogels fabricated through controlled permeation of Fe exhibit prominent and well-balanced mechanical properties (, the tensile strength can reach 10.

Structural reorganization and crack-healing properties of hydrogels based on dynamic diselenide linkages.

We report the dynamic behavior of diselenide-containing hydrophilic polyurethanes and hydrogels based on diselenide exchange reactions in an aqueous media. Diselenide-containing linear and cross-linked polyurethanes were synthesized via polyaddition reactions using diselenide-containing diol in combination with pyridinium diol that enhances the hydrophilicity of the polymer chains. The obtained linear polyurethanes underwent photo-induced diselenide exchange reactions with small diselenide compounds and degraded to smaller fragments, confirming the dynamicity of the obtained hydrophilic polyurethanes.

How can multi-bond network hydrogels dissipate energy more effectively: an investigation on the relationship between network structure and properties.

Constructing a multi-bond network (MBN), which involves hierarchical dynamic bonds with different bond association energies, is an effective method for achieving super tough hydrogels. In this work, a small amount of poly(vinyl alcohol) (PVA) is introduced into a loosely chemically crosslinked poly(acrylic acid) (PAA) network. The hydrophilic PVA chains can physically interact and form hydrogen bonds with the PAA chains.

Homogeneous and Real Super Tough Multi-Bond Network Hydrogels Created through a Controllable Metal Ion Permeation Strategy.

Poly(acrylic acid) (PAA) hydrogels with a multi-bond network composed of sparse chemical cross-links and carboxyl-Fe coordination are prepared through a controllable permeation strategy utilizing ferric citrate (FeCA). The existing strategies that directly soak PAA hydrogels in Fe solutions usually induce an inhomogeneous network with densely cross-linked shells and uncertain water content of the hydrogels, which brings about ambiguity when investigating strengthening mechanisms because water content significantly affects the mechanical properties of hydrogels. Herein, the controllable permeation of Fe into PAA networks based on the competition between citric acid (CA)-Fe chelation and PAA-Fe coordination guarantees sustained release of Fe, facilitating homogeneous distribution of ionic cross-links and a certain water content.

Coordination-Driven Hierarchical Assembly of Hybrid Nanostructures Based on 2D Materials.

2D materials have received tremendous scientific and engineering interests due to their remarkable properties and broad-ranging applications such as energy storage and conversion, catalysis, biomedicine, electronics, and so forth. To further enhance their performance and endow them with new functions, 2D materials are proposed to hybridize with other nanostructured building blocks, resulting in hybrid nanostructures with various morphologies and structures. The properties and functions of these hybrid nanostructures depend strongly on the interfacial interactions between 2D materials and other building blocks.

High-performance multi-functional graphene/hexagonal boron nitride/poly(ethylene oxide) nanocomposites through enhanced interfacial interaction by coordination.

In this study, multi-functional nanocomposites with excellent mechanical, electrical and thermal properties were prepared through metal-ion coordination. Reduced graphene oxide (rGO) and hexagonal boron nitride (h-BN) interacted through calcium coordination bonding. Poly(ethylene oxide) (PEO) was added to bridge these two nanomaterials, providing more resistance to tensile deformation.

Ultrathin MXene Nanosheets Decorated with TiO Quantum Dots as an Efficient Sulfur Host toward Fast and Stable Li-S Batteries.

Being conductive and flexible, 2D transition metal nitrides and carbides (MXenes) can serve in Li-S batteries as sulfur hosts to increase the conductivity and alleviate the volume expansion. However, the surface functional groups, such as OH and F, weaken the ability of bare MXenes in the chemisorption of polysulfides. Besides, they create numerous hydrogen bonds which make MXenes liable to restack, resulting in substantial loss of active area and, thus, inaccessibility of ions and electrolyte.

Elaborate synthesis of black tin oxide-black titanium oxide core-shell nanotubes for ultrastable and fast lithium storage.

Herein, we report on the elaborate synthesis of a novel hybrid architecture, i.e., black tin oxide-black titanium oxide core-shell nanotubes (denoted as TiO2-x@SnO2-x nanotubes) by NaBH4 co-reduction.

Robust and self-healable nanocomposite physical hydrogel facilitated by the synergy of ternary crosslinking points in a single network.

Acrylamide (AM) and a small amount of stearyl methacrylate (C18) hydrophobic monomer copolymerize to graft on the surface of vinyl hybrid silica nanoparticles (VSNPs), forming nanobrush gelators, thereby constructing ternarily crosslinked nanocomposite physical hydrogels (TC-NCP gels). The TC-NCP gel is composed of a single network ternarily crosslinked by hydrogen bonds and hydrophobic interactions among the grafting polymer chains as physical cross-linking points and thus the polymer grafted VSNPs as analogous covalent crosslinking points. Under stretching, the physical crosslinking points successively break to gradually dissipate energy and then recombine to homogenize the network.

Facile and Green Production of Impurity-Free Aqueous Solutions of WS Nanosheets by Direct Exfoliation in Water.

To obtain 2D materials with large quantity, low cost, and little pollution, liquid-phase exfoliation of their bulk form in water is a particularly fascinating concept. However, the current strategies for water-borne exfoliation exclusively employ stabilizers, such as surfactants, polymers, or inorganic salts, to minimize the extremely high surface energy of these nanosheets and stabilize them by steric repulsion. It is worth noting, however, that the remaining impurities inevitably bring about adverse effects to the ultimate performances of 2D materials.

Aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles for superior lithium storage.

We report the aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles by controlled transformation and organization. The synergistically integrated merits of a simple process and delicate structural design lay a basis for developing an industrially viable silicon anode with optimized electrochemical performances.

Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined.

Constructing Novel Si@SnO2 Core-Shell Heterostructures by Facile Self-Assembly of SnO2 Nanowires on Silicon Hollow Nanospheres for Large, Reversible Lithium Storage.

Developing an industrially viable silicon anode, featured by the highest theoretical capacity (4200 mA h g(-1)) among common electrode materials, is still a huge challenge because of its large volume expansion during repeated lithiation-delithiation as well as low intrinsic conductivity. Here, we expect to address these inherent deficiencies simultaneously with an interesting hybridization design. A facile self-assembly approach is proposed to decorate silicon hollow nanospheres with SnO2 nanowires.

h-BN Nanosheets as 2D Substrates to Load 0D Fe3O4 Nanoparticles: A Hybrid Anode Material for Lithium-Ion Batteries.

h-BN, as an isoelectronic analogue of graphene, has improved thermal mechanical properties. Moreover, the liquid-phase production of h-BN is greener since harmful oxidants/reductants are unnecessary. Here we report a novel hybrid architecture by employing h-BN nanosheets as 2D substrates to load 0D Fe3O4 nanoparticles, followed by phenol/formol carbonization to form a carbon coating.

Self-healable, super tough graphene oxide-poly(acrylic acid) nanocomposite hydrogels facilitated by dual cross-linking effects through dynamic ionic interactions.

Here we propose a facile, one-pot in situ free radical polymerization strategy to prepare self-healable, super tough graphene oxide (GO)-poly(acrylic acid) (PAA) nanocomposite hydrogels by using Fe ions as a cross-linker. The 3-dimensional network structure of the GO-PAA nanocomposite hydrogels is facilitated by dual cross-linking effects through dynamic ionic interactions: (i) the first cross-linking points are Fe ions creating ionic cross-linking among PAA chains; (ii) the second cross-linking points are GO nanosheets linking PAA chains through Fe coordination. When the GO-PAA nanocomposite hydrogels are under stretching conditions, the ionic interactions among PAA chains can dynamically break and recombine to dissipate energy, while the GO nanosheets coordinated to the PAA chains maintain the configuration of the hydrogels and work as stress transfer centers transferring the stress to the polymer matrix.

Self-healable, tough and highly stretchable ionic nanocomposite physical hydrogels.

We present a facile strategy to synthesize self-healable tough and highly stretchable hydrogels. Our design rationale for the creation of ionic cross-linked hydrogels is to graft an acrylic acid monomer on the surface of vinyl hybrid silica nanoparticles (VSNPs) for the growth of poly(acrylic) acid (PAA), and the obtained VSNP-PAA nanobrush can be used as a gelator. Physical cross-linking through hydrogen bonding and ferric ion-mediated ionic interactions between PAA polymer chains of the gelators yielded ionic nanocomposite physical hydrogels with excellent and balanced mechanical properties (tensile strength 860 kPa, elongation at break ∼2300%), and the ability to self-repair (tensile strength ∼560 kPa, elongation at break ∼1800%).

Highly stretchable and super tough nanocomposite physical hydrogels facilitated by the coupling of intermolecular hydrogen bonds and analogous chemical crosslinking of nanoparticles.

Highly stretchable and super tough nanocomposite physical hydrogels (NCP gels) were fabricated by a facile and one-pot process. NCP gels show superior mechanical properties with tensile strength of 73 kPa-313 kPa and elongation at break of 1210-3420%. This is due to the effective strengthening mechanism: under stretching, the intermolecular hydrogen bonds can dynamically break and recombine to dissipate energy and homogenize the gel network.

Predictive supracolloidal helices from patchy particles.

A priori prediction of supracolloidal architectures from nanoparticle and colloidal assembly is a challenging goal in materials chemistry and physics. Despite intense research in this area, much less has been known about the predictive science of supracolloidal helices from designed building blocks. Therefore, developing conceptually new rules to construct supracolloidal architectures with predictive helicity is becoming an important and urgent task of great scientific interest.

Coordination-driven hierarchical assembly of silver nanoparticles on MoS2 nanosheets for improved lithium storage.

We report a novel strategy for the hierarchical assembly of Ag nanoparticles (NPs) on MoS2 nanosheets through coordination by using a multifunctional organic ligand. The presence of Ag NPs on the surface of MoS2 nanosheets inhibits their agglomeration, thereby providing increased interlayer spacing for easy Li(+) ion intercalation. Such a unique hybrid architecture also ensures sufficient percolation pathways on the whole surface of the MoS2 nanosheets.

Flexible and robust MoS2-graphene hybrid paper cross-linked by a polymer ligand: a high-performance anode material for thin film lithium-ion batteries.

A flexible and robust MoS2-graphene hybrid paper with an excellent lithium storage capacity is fabricated through cross-linking by a polymer ligand, PEO, and shows potential for the development of high-performance film anodes.