Chemistry of Materials最新文献

Single-walled carbon nanotubes (SWNTs) are promising materials for building transparent conducting films (TCFs). Nevertheless, commercially available SWNTs exhibit low purity and poor solubility. Conjugated polymers (CPs) have been widely reported to disperse SWNTs in organic solvents; however, converting CP-SWNT dispersions into TCFs has never been investigated. In this study, we used the poly(fluorene-co-phenylene) CP with self-immolative linkers (SILs) within its side chains to disperse SWNTs. The SIL enables clean and fast side chain removal from the CP-SWNT complex upon simple treatment with tetra-n-butylammonium fluoride (TBAF) and subsequently decreases the sheet resistance (R_s) of the CP-SWNT thin films. We explored a highly reproducible method to manufacture CP-SWNT-TCFs on a Mylar substrate. All CP-SWNT-TCFs showed a significant decrease in R_s post TBAF treatment, suggesting that eliminating the side chain can decrease R_s while preserving %transmittance. Notably, these CP-SWNT-TCF films exhibited consistent R_s across various bending radii and after 200 bending cycles, highlighting their applicability in flexible electronics. This proof-of-concept study opens up avenues to produce CP-SWNT-TCF and further enhance their electrical conductivity by removing CP side chains.

Area-selective deposition (ASD) is a bottom-up patterning technique that is of interest for nanoprocessing and next-generation semiconductor device manufacturing. This work demonstrates the great potential of dechlorosilylation chemistry for ASD through the example of Ge₂Sb₂Te₅ (GST), a promising phase change material for storage class memory (SCM) applications. The fabrication of SCM devices may be facilitated by ASD as it involves complex nanoscale three-dimensional structures. We therefore investigate GST ASD on a TiN growth area with SiO₂ as a nongrowth area. A selectivity of >0.9 is maintained up to ∼45 nm of GST by using a single reaction of an aminosilane small molecule inhibitor in combination with GST atomic layer deposition (ALD) with GeCl₂·C₄H₈O₂, SbCl₃, and Te[(CH₃)₃Si]₂ as precursors at 70 °C. The high selectivity is maintained for much thicker films compared to that of previously investigated ALD chemistries that use other precursors and O₂, H₂O, or NH₃ co-reagents in combination with the same inhibitor. Interestingly, the selectivity, the ideal 2:2:5 composition, and the amorphous phase of Ge₂Sb₂Te₅ are maintained during ASD on SiO₂/TiN line patterns with a half-pitch of 45 nm. A careful study of the growth evolution suggests that the growth mechanism for ASD on these nanopatterns relies on diffusion in addition to adsorption, indicating that diffusion-mediated selective deposition is not limited to metal ASD processes such as those of Ru and Pt. We propose that the combination of the ALD dechlorosilylation chemistry with passivation approaches including small molecule inhibitors creates a promising avenue for expanding the ASD material space to a wide range of new materials, enabling new applications for ASD in nanoelectronics, nanoprocessing, catalysis, etc.

Guanine crystals are frequently encountered in nature in the β-polymorph to create structural colors, to enhance the vision of creatures, and for camouflage. Unfortunately, it is challenging to control the crystallization of guanine in aqueous conditions in the laboratory because of its low solubility in water. Here, we crystallize guanine in an aqueous environment under confinement. We employ water–oil–water double emulsions stabilized with a metal–ligand functionalized surfactant as selectively permeable containers to crystallize guanine by dynamically adjusting the pH and guanine concentration. If formed under high osmotic pressures that result in high guanine concentrations within emulsion cores, guanine crystallizes into the anhydrous β-polymorph with a spherical morphology. In contrast, if crystals form within emulsion cores containing low guanine concentrations, they attain the monohydrate form possessing a needle-like morphology. These findings demonstrate for the first time that the structure and morphology of guanine crystals formed in the laboratory under confinement in an aqueous environment can be tuned by the local guanine concentration and to some extent by the solution pH.

The development of flexible and wearable electronics has grown in recent years with applications in different fields of industry and science. Consequently, the necessity of functional, flexible, safe, and reliable energy storage devices to meet this demand has increased. Since the classical electrochemical systems face structuration and operational limitations to match the needs of flexible devices, novel approaches have been in the research spotlight: gel polymer electrolytes (GPEs). Combining comparable ionic conductivity with liquid electrolytes with desirable mechanical stability, GPEs have been investigated in various electrochemical applications in sensors, actuators, and energy storage. This versatile class of quasi-solid material finds applications in the different components of energy storage devices. They are being investigated as electrodes, binders, electrolytes, and stand-alone systems due to desirable physical-chemical characteristics such as a wider potential operational window and high adhesion to solid electrode materials. Coalescing a liquid phase occluded into an entangled 3D polymeric matrix, these materials withstand elevated mechanical stress such as strain and compression, and they are also interesting materials for various applications. Moreover, they allow further functionalization to match the specific requirements of various energy storage systems. In this review, we summarize different applications of GPEs in energy storage devices, highlighting many valuable properties and emphasizing their enhancements compared to classical liquid electrochemical energy storage systems.

The Solid-State Materials Chemistry Data Science Hackathon (SSMCDAT), held at Lehigh University from January 19–21, 2023, demonstrated the power of interdisciplinary collaboration in tackling challenges in solid-state materials chemistry. This article highlights key outcomes, participant feedback, and future research and collaboration pathways.

Phase-pure polycrystalline Ba₄RuMn₂O₁₀ was prepared and determined to adopt the noncentrosymmetric polar crystal structure (space group Cmc2₁) based on results of second harmonic generation, convergent beam electron diffraction, and Rietveld refinements using powder neutron diffraction data. The crystal structure features zigzag chains of corner-shared trimers, which contain three distorted face-sharing octahedra. The three metal sites in the trimers are occupied by disordered Ru/Mn with three different ratios: Ru1:Mn1 = 0.202(8):0.798(8), Ru2:Mn2 = 0.27(1):0.73(1), and Ru3:Mn3 = 0.40(1):0.60(1), successfully lowering the symmetry and inducing the polar crystal structure from the centrosymmetric parent compounds Ba₄T₃O₁₀ (T = Mn, Ru; space group Cmca). The valence state of Ru/Mn is confirmed to be +4 according to X-ray absorption near-edge spectroscopy. Ba₄RuMn₂O₁₀ is a narrow bandgap (∼0.6 eV) semiconductor exhibiting spin-glass behavior with strong magnetic frustration and antiferromagnetic interactions.

The construction of functional chiral polymers with newly built chiral centers from entire achiral monomers is charming but challenging in chiral material science. In this work, an asymmetric multicomponent polymerization (aMCP) of aromatic primary amines, aromatic aldehydes, and alkynes was developed with the catalysis of CuOTf-pybox complex to produce chiral poly(propargylamine)s. The supramolecular interactions between the CuOTf-pybox complex and the reactive species not only assisted the formation of a preorganized intermediate state to induce stereoselective reaction to produce chiral polymers but also reduced the reaction-activated energy to enable efficient A³-polycoupling at room temperature, affording chiral poly(propargylamine)s with high yields (up to 96%), high molecular weights (M_ns up to 44 800 g/mol), significant circular dichroism signal, good solubility, and high thermal stability. Moreover, the unique chiral aromatic poly(propargylamine)s with remaining N–H moieties enabled complete conversion to a new group of chiral polyheterocycles, poly(thiazolidine-2-imine)s with elongated conjugation and enhanced fluorescence, realizing polymer backbone transformation through facile reaction with benzoyl isothiocyanate. The aMCP has provided an efficient and convenient approach for the construction of chiral polymers with diversified structures from simple achiral monomers and may accelerate the development of chiral polymer materials.

NIR-mediated upconversion photochemistry stands as a powerful tool for noninvasive tissue engineering with excellent depth penetration. However, challenges such as low NIR upconversion and photochemical efficiencies, coupled with the moderate mechanical properties of upconversion hydrogels, hinder their advanced applications, particularly in oxygen- and water-rich physiological environments. This study addresses these limitations by strategically considering the interfacial effect and implementing a well-thought-out design for rapid NIR-mediated upconversion photochemistry, thereby developing high-performance upconversion hydrogels in vivo. Leveraging strong hydrophobic and electrostatic interactions at the interface of upconversion nanoparticles and hydrogel matrices enables us to achieve a remarkable 6-fold increase in fluorescent upconversion emission. This strategic enhancement in NIR photochemistry facilitates the rapid one-step formation of hierarchical upconversion hydrogels deep within tissues, significantly reducing fabrication time from approximately 6 min to 45 s. Meanwhile, these stretchable tough upconversion hydrogels experience impressive increases in mechanical properties by 3–10 times. Such rapid and controllable NIR photochemistry is compatible with standard printing techniques, allowing for the remote fabrication of complex structures beneath the skin. Moreover, as-prepared biocompatible upconversion hydrogels exhibit enhanced antimicrobial activity, surpassing typical bacteria, such as Escherichia coli and Staphylococcus aureus. With these notable advantages, the potential of this upconversion photochemistry extends beyond tissue engineering to include synergistic noninvasive biofilm elimination and tissue repair. Its promising applications span diverse fields, encompassing photochemistry, materials, engineering, and information sciences.

While the chemical stoichiometry does not change with a reduction in layer numbers for most of the two-dimensional (2D) layered materials, the multilayer Pd₂Se₃ in the noble transition-metal chalcogenides (NTMDs) group changes its stoichiometry to palladium diselenide (PdSe₂) in the bilayer form under Se-rich growth conditions. The experimental realization of PdSe₂–Pd₂Se₃ junctions and their application in various sensing applications are yet to be explored. Herein, we introduce a salt (NaCl) catalyzed chemical vapor deposition growth of bilayer (2L) PdSe₂ dendrites and PdSe₂–Pd₂Se₃ junctions on the mica substrate through the salt solution pretreatment. The pretreated structure triggers the formation of molten Pd–O droplets, which undergo a phase evolution from Pd nanoparticles (NPs) to Pd₂Se₃ (in Se-poor condition) to PdSe₂ (in Se-rich condition). Dendritic 2L PdSe₂ can be transferred from a growth substrate to an arbitrary substrate on a centimeter-scale through a polymer-free water-assisted transfer technique, which results in abundant PdSe₂–Pd₂Se₃ junctions due to the vacancy creation during the transfer process. Remarkably, Pd NPs hotspots on PdSe₂–Pd₂Se₃ junctions enable significant surface-enhanced Raman scattering (SERS) enhancement with an enhancement factor (EF ∼ 3 × 10⁵), which is more than 1 order of magnitude higher than that of 2L PdSe₂ to detect methylene blue molecules due to multiple factors, such as charge transfer and electromagnetic field enhancement. This is confirmed by density functional theory calculations and Finite element method (FEM) simulation, along with Raman imaging. The FEM simulations revealed an electric field enhancement factor of 5.546 × 10³ for Pd NPs decorated bilayer PdSe_2, and the remaining enhancement factor is expected to be contributed by charge transfer mechanisms. This work divulges the controllable protocol for the low-temperature chemical vapor deposition growth of 2L PdSe₂ and PdSe₂–Pd₂Se₃ junctions with facile transfer to arbitrary substrates and is indispensable for unleashing its full potential in a wide range of sensing, electronic, photonic, and biomedical applications.