A molecularly engineered dual-crosslinked hydrogel with extraordinary mechanical properties is reported. The hydrogel network is formed with both chemical crosslinking and acrylic-Fe(III) coordination; these, respectively, impart the elasticity and enhance the mechanical properties by effectively dissipating energy. The optimal hydrogel achieves a tensile stress of ca. 6 MPa at a large elongation ratio (>7 times), a toughness of 27 MJ m(-3) , and a stiffness of ca. 2 MPa, and has good self-recovery properties.

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Biomimetic self-healing superamphiphobicity is reported on a rough alumina surface with a large number of nanopores that act as nanoreserviors for low surface energy materials that can consecutively release and heal the damaged surface.

A generalized surface-initiated photografting procedure, which utilizes polydopamine as a photosensitive initiating layer, allows functionalization of almost any substrate with thin polymer films under sunlight.

The poor mechanical strength of hydrogels has largely limited their wide applications, and improving hydrogels' mechanical strength is a hot and important topic in the hydrogel research field. Although many successful strategies have been proposed to improve hydrogels' mechanical strength during the past decades, a hydrogel with a tensile stress surpassing dozens of mega Pascal is desirable, yet still a big challenge. To address this issue, the Fe(3+) -mediated physical crosslinking formed under stretch conditions was employed in a chemically crosslinked poly (acrylamide-co-acrylic acid) network to achieve a dual-crosslinked hydrogel. The expected molecular orientation occurs under stretch and allows the maximumu chelating interaction between pendant carboxylic anions and Fe(3+) and molecules conformation being frozen, leading to the mechanical strength improving dramatically. As a result, an unprecedentedly high mechanical strength, but anisotropic dual-crosslinked hydrogel was obtained. By optimizing the experimental parameters, the nominal tensile stress along pre-stretching direction can reach as high as ≈40 MPa with elastic modulus of ≈40 MPa at large strain (>200%). In addition, the molecular orientation also leads to big difference of mechanical performance between parallel and perpendicular direction.

This paper describes a standard replication approach for preparing transparent elastomeric conductors with single-walled carbon nanotubes (SWCNTs) inlaid just below the surface. The elastic conductors were fabricated by spray coating a SWCNT suspension in chloroform on a fluorinated substrate, followed by the standard replication, casting liquid elastomers like polydimethylsiloxane on the SWCNT film, curing and peeling off the substrate. The replication strategy can produce elastic conductors with a flat or a desirable patterned surface. The resultant elastic conductors had excellent stability under repeated mechanical loading and stretchability up to 300%. It retained conductance even after 10 tape tests. Using the SWCNT-inlaid stretchable conductors as electrodes, elastic capacitors were fabricated using a mask-assisted method. The results showed that these capacitors are good candidates for multifunctional capacitive pressure, strain, and touch sensors.

3D printing of hydrogels with high intrinsic mechanical performance has significant applications in many fields yet has been proven to be a fundamental challenge. Here, 3D printing of ultrahigh strength hydrogels is achieved by constructing cross-linkingDPC networks based on poly­(vinyl alcohol) (PVA) and chitosan (CS). The hybrid ink with moderate rheology for direct ink writing is employed to manufacture complex hydrogel structures, first. Then, the cyclic freezing–thawing followed by sodium citrate solution soaking realize the first network of PVA crystallization and the second one of CS ionic interaction between amino and carboxyl groups. The optimized DPC hydrogel displays a tensile strength of 12.71 ± 1.32 MPa at a strain of 302.27 ± 15.70%, Young’s modulus of 14.01 ± 1.35 MPa, and work of extension at fracture W ext of 22.10 ± 2.36 MJ m–3 because of the dominant energy dissipation of the stiff CS ionic network. Moreover, the tearing test supports that this DPC hydrogel possesses a high toughness of 9.92 ± 1.05 kJ m–2. This protocol can readily realize not only the hydrogel lattice, honeycomb, and spring, but also secondary-shaping hydrogel objects including whale, octopus, and butterfly via a local DPC strategy. Integrating the advanced 3D-printing technique with high-performance hydrogels uncovers a feasible strategy to broad practical applications in engineering, intelligent machine, and soft robotics.

Three-dimensional printing was used to fabricate various metallic structures by directly integrating a Br-containing vinyl-terminated initiator into the 3D resin followed by surface-initiated atomic-transfer radical polymerization (ATRP) and subsequent electroless plating. Cu- and Ni-coated complex structures, such as microlattices, hollow balls, and even Eiffel towers, were prepared. Moreover, the method is also capable of fabricating ultralight cellular metals with desired structures by simply etching the polymer template away. By combining the merits of 3D printing in structure design with those of ATRP in surface modification and polymer-assisted ELP of metals, this universal, robust, and cost-effective approach has largely extended the capability of 3D printing and will make 3D printing technology more practical in areas of electronics, acoustic absorption, thermal insulation, catalyst supports, and others.