A Multifunctional Interlocked Binder with Synergistic In Situ Covalent and Hydrogen Bonding for High-Performance Si Anode in Li-ion Batteries.

Silicon has garnered significant attention as a promising anode material for high-energy density Li-ion batteries. However, Si can be easily pulverized during cycling, which results in the loss of electrical contact and ultimately shortens battery lifetime. Therefore, the Si anode binder is developed to dissipate the enormous mechanical stress of the Si anode with enhanced mechanical properties. However, the interfacial stability between the Si anode binder and Cu current collector should also be improved. Here, a multifunctional thiourea polymer network (TUPN) is proposed as the Si anode binder. The TUPN binder provides the structural integrity of the Si anode with excellent tensile strength and resilience due to the epoxy-amine and silanol-epoxy covalent cross-linking, while exhibiting high extensibility from the random coil chains with the hydrogen bonds of thiourea, oligoether, and isocyanurate moieties. Furthermore, the robust TUPN binder enhances the interfacial stability between the Si anode and current collector by forming a physical interaction. Finally, the facilitated Li-ion transport and improved electrolyte wettability are realized due to the polar oligoether, thiourea, and isocyanurate moieties, respectively. The concept of this work is to highlight providing directions for the design of polymer binders for next-generation batteries.

Regional Control of Multistimuli-Responsive Structural Color-Switching Surfaces by a Micropatterned DNA-Hydrogel Assembly.

Structural colors have advantages compared with chemical pigments or dyes, such as iridescence, tunability, and unfading. Many studies have focused on developing the ability to switch ON/OFF the structural color; however, they often suffer from a simple and single stimulus, remaining structural colors, and target selectivity. Herein, we present regionally controlled multistimuli-responsive structural color switching surfaces. The key part is the utilization of a micropatterned DNA-hydrogel assembly on a single substrate. Each hydrogel network contains a unique type of stimuli-responsive DNA motifs as an additional cross-linker to exhibit swelling/deswelling via stimuli-responsive DNA interactions. The approach enables overcoming the existing limitations and selectively programming the DNA-hydrogel to a decrypted state (ON) and an encrypted state (OFF) in response to multiple stimuli. Furthermore, the transitions are reversible, providing cyclability. We envision the potential of our method for diverse applications, such as sensors or anticounterfeiting, requiring multistimuli-responsive structural color switching surfaces.

A 4D Printable Shape Memory Vitrimer with Repairability and Recyclability through Network Architecture Tailoring from Commercial Poly(ε-caprolactone).

Vitrimers have shown advantages over conventional thermosets via capabilities of dynamic network rearrangement to endow repairability as well as recyclability. Based on such characteristics, vitrimers have been studied and have shown promises as a 3D printing ink material that can be recycled with the purpose of waste reduction. However, despite the brilliant approaches, there still remain limitations regarding requirement of new reagents for recycling the materials or reprintability issues. Here, a new class of a 4D printable vitrimer that is translated from a commercial poly(ε-caprolactone) (PCL) resin is reported to exhibit self-healability, weldability, reprocessability, as well as reprintability. Thus, formed 3D-printed vitrimer products show superior heat resistance in comparison to commercial PCL prints, and can be repeatedly reprocessed or reprinted via filament extrusion and a handheld fused deposition modeling (FDM)-based 3D printing method. Furthermore, incorporation of semicrystalline PCL renders capabilities of shape memory for 4D printing applications, and as far as it is known, such demonstration of FDM 3D-printed shape memory vitrimers has not been realized yet. It is envisioned that this work can fuel advancement in 4D printing industries by suggesting a new material candidate with all-rounded capabilities with minimized environmental challenges.

Spatiotemporally Controlled Plasticity and Elasticity in 3D Multi-Shape Memory Structures Enabled by Elemental Sulfur-Derived Polysulfide Networks with Intrinsic NIR Responsiveness.

Thermadapt shape memory polymers (SMPs), utilizing a variety of dynamic covalent bond exchange mechanisms, have been extensively studied in recent years but it is still challenging to address several constraints in terms of limited accuracy and complexity for constructing 3D shape memory structures. Here, an effective and facile preparation of thermadapt SMPs based on elemental sulfur-derived poly(phenylene polysulfide) networks (PSNs) is presented. These SMPs possess intrinsic near-infrared (NIR)-induced photothermal conversion properties for spatiotemporal control of their plasticity and elasticity. The NIR-controllable plasticity and elasticity of the PSNs enable versatile shape manipulation of 3D multi-shape memory structures, including building block assembly, reconfiguration, shape fixing/recovery, and repair.

Enhanced thermoelectric performance of bar-coated SWCNT/P3HT thin films.

The influence of processing conditions, such as ink concentration and coating method, on the thermoelectric properties of SWCNT/P3HT nanocomposite films was investigated systematically. Using simple wire-bar-coating, SWCNT/P3HT nanocomposite films with high thermoelectric performance could be obtained without additional P3HT doping. The wire-bar-coated SWCNT/P3HT nanocomposite films exhibited power factors of up to 105 µW m(-1) K(-2) at room temperature. The SWCNT bundles with diameters in the range of 6-23 nm formed an interconnected network in the wire-bar-coated nanocomposite films. Network formation in these nanocomposite films was expected to be strongly related to the development of electrical pathways due to inter-SWCNT bundle connections. This study suggests that the thermoelectric performance of SWCNT/P3HT nanocomposite films could be optimized by controlling their processing conditions and morphology.