Super-expansive thermo-reversible interstitial solid solution of nanocrystal superlattices with mesogens

Nature Materials · 2025-11-28

Nanomaterials and Light Addressing Grand Challenges: 2025 Benjamin Franklin Medal in Chemistry presented to Naomi J. Halas, Ph.D․

Journal of the Franklin Institute · 2025-10-30

Wet Spun Aramid Nanofiber-Templated Hybrid Hydrogel Desiccant Filaments for Atmospheric Water Harvesting

ACS Applied Materials & Interfaces · 2025-11-12 · 1 citations

Atmospheric water vapor is an abundant and renewable resource that can alleviate growing water scarcity. Hybrid hydrogel desiccants composed of hygroscopic salts hold significant promise for atmospheric water harvesting (AWH) due to their increased capacity for water uptake. Thus far, many efforts in fabricating these desiccants require multistep processes, where the salt impregnation is achieved post-hydrogel fabrication. Here, we develop a scalable wet spinning methodology using aramid nanofibers (ANFs) to template and coagulate hydroxypropyl cellulose (HPC) into filaments in a coagulation bath consisting of water and lithium chloride (LiCl). HPC serves as the matrix to retain the captured water vapor, and later releases it upon heating. ANFs serve as the physical cross-linker between HPC, allowing for wet spinning at a speed up to 61 m h–1. The composite filaments achieve up to 0.55 g g–1 water uptake at 30% relative humidity (RH) and 21 °C, reaching 80% saturation in 40 min. With a lower critical solution temperature of 39 °C, the desiccant filaments can release up to 72% of the captured water at 60 °C after 30 min. In an AWH chamber, the filaments can achieve daily water production of 5.21 L kg–1 day–1 at 30% RH and 21 °C.

Cavity Enhanced Emission from Telecom Rare-Earth System in Colloidal Host

ArXiv.org · 2025-10-01

Erbium incorporated in a ceria (CeO2) host offers strong potential as a spin qubit platform, providing a pathway toward telecom-compatible quantum memory. But erbium is a dim emitter due to its long excited state lifetime. Methods to enhance its emission rate and efficiency through nanophotonic cavity integration are therefore essential. In this work, we demonstrate cavity-enhanced emission from erbium doped CeO2. We couple colloidally synthesized erbium doped CeO2 nanocrystals to a silicon nanobeam cavity and show a 30-fold improvement in emitter brightness combined with a 2-fold lifetime enhancement. We estimate a lower bound of 12 for the Purcell factor of cavity-coupled emitters after accounting for non-radiative decay. These results pave the way towards utilizing colloidally synthesized optically addressable spin qubits emitting at telecom wavelength for quantum networking and distributed quantum computing.

Reversible Physical Gelation of Thermotropic Liquid Crystals Driven by Nanoplate Self-Assembly

ACS Nano · 2025-07-03

Physically gelled soft materials, driven by the self-assembly of low-molecular-mass gelators (LMGs), have emerged as a platform for designing advanced gels that exhibit reversible gelation and property tunability. Liquid crystal (LC) gels are of great interest due to their supramolecular orderings as gel hosts and their enhanced electro-optical properties. In this study, we demonstrate the physical gelation of a nematic LC driven by nanoplate self-assembly, expanding the concept of gelators from small molecules to nanoparticles. These nanoplates are functionalized with promesogenic ligands and form a fibrillar network in LCs with face-to-face interplate stacking, resembling LMGs. The critical gelation volume fraction in the tilt test is only 0.14 v %, comparable to values reported for LMGs. Rheological analyses confirm viscoelastic properties characteristic of gelation. In situ small-angle X-ray scattering (SAXS) characterizes the formation of nanoplate networks in the LC with decreasing temperature, wherein LC mesogens become trapped in pores. Molecular dynamics (MD) simulations reveal that the interaction between ligand-coated nanoplates and LC-forming mesogens induces a multidomain LC structure, increasing friction between LC domains and stabilizing the gel. This study establishes direct relationships among molecular interactions, nanostructures, and mechanical properties in physically gelled LCs. The findings inspire the future gelator design of both LMGs and nanoplates, with potential applicability in bioscaffold engineering and liquid crystalline nanocomposites.

Chemical Construction of Molecular Truss Lattices with Tunable Topologies

Journal of the American Chemical Society · 2025-10-06 · 1 citations

Engineering connectivity at the nanoscale enables unprecedented mechanical metamaterials with exotic properties. However, nanomanufacturing 3D lattices with molecular connectivity and tunable topologies is challenging. Here, we select a supramolecular material named metal–organic framework (MOF) as the prototype, where molecules are employed as nodes and beams to construct nanosized truss lattices. An MOF named PCN-700 featuring a well-defined body-centered cubic structure is synthesized, of which the molecular connectivity, topology, and internal stress can be precisely tuned via postsynthetic installation of organic linkers with variable lengths. Herein, the topology is regulated with subnanometer resolution, affording lightweight materials with tunable elastic moduli (8.9–17.4 GPa) without apparent density changes, confirmed by atomic force microscopy indentation. The study of the compressive behaviors from nanonewton to millinewton regimes establishes a connection between the intrinsic chemical structures and the mechanical properties, where the molecular connectivity determines the lattice deformation mode. Raman spectra and ab initio calculations indicate that the PCN-700 can accommodate compressive deformation through the rotation of molecular planes within the organic ligands, contributing to the integral stiffness. The insights presented here will not only uncover MOFs’ application potentials in mechanics but also inspire chemical design and precision engineering of mechanical metamaterials at the nanoscale.

Shape effects on the 2D self-assembly of lithographically fabricated nanoparticles

Nanoscale · 2025-01-01 · 1 citations

Lithographically-defined polygonal Au nanoplates assemble at liquid-air interface. Shape governs 2D order: hexagonal>pentagonal>square, correlated with coordination/tiling. Binary mixtures with compatible six-fold coordination show enhanced ordering.

Dynamic Nanocrystal Superlattices with Thermally Triggerable Lubricating Ligands

Journal of the American Chemical Society · 2024-01-31 · 13 citations

The size-dependent and collective physical properties of nanocrystals (NCs) and their self-assembled superlattices (SLs) enable the study of mesoscale phenomena and the design of metamaterials for a broad range of applications. However, the limited mobility of NC building blocks in dried NCSLs often hampers the potential for employing postdeposition methods to produce high-quality NCSLs. In this study, we present tailored promesogenic ligands that exhibit a lubricating property akin to thermotropic liquid crystals. The lubricating ability of ligands is thermally triggerable, allowing the dry solid NC aggregates deposited on the substrates with poor ordering to be transformed into NCSLs with high crystallinity and preferred orientations. The interplay between the dynamic behavior of NCSLs and the molecular structure of the ligands is elucidated through a comprehensive analysis of their lubricating efficacy using both experimental and simulation approaches. Coarse-grained molecular dynamic modeling suggests that a shielding layer from mesogens prevents the interdigitation of ligand tails, facilitating the sliding between outer shells and consequently enhancing the mobility of NC building blocks. The dynamic organization of NCSLs can also be triggered with high spatial resolution by laser illumination. The principles, kinetics, and utility of lubricating ligands could be generalized to unlock stimuli-responsive metamaterials from NCSLs and contribute to the fabrication of NCSLs.

Building Therapies Layer-by-Layer: 2024 Benjamin Franklin Medal in Chemistry presented to Paula T. Hammond, Ph.D.

Journal of the Franklin Institute · 2024-10-30

Growth of Nanocrystal Superlattices from Liquid Crystals

Journal of the American Chemical Society · 2024-04-11 · 6 citations

The growth of superlattices (SLs) made from self-assembled nanocrystals (NCs) is a powerful method for creating new materials and gaining insight into fundamental molecular dynamics. Previous explorations of NCSL syntheses have mostly compared them to crystallization. However, NCSL synthesis has not broadly shown cooling crystallization from saturated solutions as a reversible crystallization-dissolution process. We demonstrate the reversible growth of NCSLs by dispersing NCs in liquid crystal (LC) "smart solvents," and harnessing the transitions between the isotropic and nematic phases of the LCs. The growth mode and morphology can be tuned. This process is a model platform for studying crystallization and demonstrates great potential in manufacturing NCSLs as colloidal crystals through liquid-phase epitaxy or colloidal synthesis.