Water-Sintered Transient Nanocomposites Used as Electrical Interconnects for Dissolvable Consumer Electronics.

Rapid development of electronic technology shortens the development time for new products and accelerates the obsolescence of consumer electronics, resulting in the explosive growth of electronic waste that is difficult to recycle and hazardous to the environment and human health. Transient electronics that can dissolve in water may potentially be adopted to tackle the issues of electronic waste; however, promising approaches to yield large-scale and high-performance transient consumer electronics have not yet been developed. Here, the joint effect of galvanic corrosion and redeposition has been utilized to develop bimetallic transient nanocomposites, which can be printed and water-sintered to yield high-performance transient PCB circuits with excellent electrical conductivity and mechanical robustness. The entire sintering process requires no external energy and strict environmental conditions. The achieved PCB circuits offer a conductivity of 307,664.4 S/m that is among the highest in comparison with other printed transient circuits. The supreme performance of the transient circuits eventually leads to the first dissolvable smartwatch that offers the same functions and similar performance as conventional smartwatches and dissolves in water within 40 h. The joint effect of galvanic corrosion and redeposition between two metals with distinct activities leads to novel nanocomposites and processing techniques of transient electronics. The resulting high-performance transient devices may reshape the appearance of consumer electronics and reform the electronics recycling industry by reducing recycling costs and minimizing environmental pollution and health hazard.

Supersoft Elastic Bottlebrush Microspheres with Stimuli-Responsive Color-Changing Properties in Brine.

Solvent-free supersoft elastomer is highly desirable for building photonic structures with significant stimuli-responsive color changes. We report supersoft elastic porous microspheres with vivid structural colors obtained via self-assembly of amphiphilic bottlebrush block copolymers at the water/oil interface templated by ordered water-in-oil-in-water double emulsions. The porous structure is composed of cross-linked bottlebrush polydimethylsiloxane (PDMS) as the supersoft elastic skeleton and bottlebrush poly(ethylene oxide) (PEO) as the internal responsive layer. The obtained microspheres show large reversible volume changes through well-controlled dehydration or hydration of PEO in response to salt ions in an aqueous environment. As a result, full-spectrum colors are obtained dependent on different salt concentrations. In-situ observation of color reflection of a microsphere indicates a gradual structural transition from the outside to the inside corresponding to migration of water molecules and salt ions. Moreover, rod-like bottlebrush PEO exhibits an anion-induced salting-out behavior different from that of random coil polymers. The significantly responsive behaviors of bottlebrush block copolymer (BBCP) assemblies in the presence of salt ions primarily rely on the supersoft elastic skeleton of the porous structure, providing a facile route to the creation of stimuli-responsive photonic materials by low-cost self-assembly methods.

In situ intercalation of Au nanoparticles and magnetic γ-Fe2O3 in the walls of MCM-41 with abundant void defects for highly efficient reduction of 4-nitrophenol and organic dyes.

Nowadays, agglomeration and leaching of metal active sites during reaction and recycle processes are considered to be a thorny problem for noble metal-based catalysts. Therefore, to make improvements, nano-gold was selected as a representative research object for many noble metals. In this study, Au nanoparticles (NPs) and magnetic γ-Fe2O3 were intercalated in situ in the walls of MCM-41 via a one-pot hydrothermal method, in which the intercalation process was preceded by co-condensation of tetraethyl orthosilicate (TEOS) with MPTS-Au complexes ((3-mercaptopropyl)-trimethoxysilane (MPTS), HAuCl4·3H2O), and a Fe3O4 sol. By the confinement of silica, Au NPs and γ-Fe2O3 were well dispersed in the walls of MCM-41, the sintering and loss of Au NPs was highly restricted, and the magnetic property of γ-Fe2O3 facilitated the recycling of Au-based catalysts. Additionally, abundant void defects appeared in MCM-41 by assembly of micelles in different sizes and shapes, greatly improving the surface area of target catalysts (>1800 m2 g-1), which provided more opportunities for contact and collision between reactors and gold active sites, effectively solving the problem of mass transportation. As expected, a series FeAu@MCM-41 catalysts showed superior catalytic activity in the reduction of 4-nitrophenol (4-NP) and organic dyes (MB, RhB, and MO), and these catalysts were recycled five times without significant loss of metal species or catalytic activity. This is attributed to the confinement effect of the silica walls and the excellent magnetic properties of γ-Fe2O3. This special structure of FeAu@MCM-41 catalysts provides more insights for designing and fabricating noble metal-based catalysts with desirable performances.

Silver-Incorporated Mussel-Inspired Polydopamine Coatings on Mesoporous Silica as an Efficient Nanocatalyst and Antimicrobial Agent.

To tackle severe environmental pollution, a search for materials by economical and eco-friendly preparations is demanding for public health. In this study, a novel in situ method to form silver nanoparticles under mild conditions was developed using biomimetic reducing agents of polydopamine coated on the rodlike mesoporous silica of SBA-15. The synthesized SBA-15/polydopamine (PDA)/Ag nanocomposites were characterized by a combination of physicochemical and electrochemical methods. 4-Nitrophenol (4-NP) and methylene blue (MB) were used as models for the evaluation of the prepared nanocatalysts of SBA-15/PDA/Ag in which the composite exhibited enhanced catalytic performance toward degrading 4-NP in solution and MB on the membrane, respectively. Additionally, compared with that of solid core-shell SiO2/PDA/Ag, tubular SBA-15/PDA/Ag showed the prolonged inhibitory effect on microbial growth as typified by Escherichia coli (60 h), Staphylococcus aureus (36 h), and Aspergillus fumigatus (60 h), which demonstrated efficient control of silver nanoparticles release from the mesopores. The constructed dual-functional SBA-15/PDA/Ag as the long-term antimicrobial agent and the catalyst of industrial products provides an integrated nanoplatform to deal with environmental concerns.