Chemistry of Materials最新文献

Fluorinated donor–acceptor(D–A) conjugated polymersare promising organic thermoelectric (OTE) materials; however, theeffects of fluorination pattern on their charge transport and dopingbehavior remain unclear. Herein, we present a regioisomeric designstrategy wherein fluorine atoms were selectively introduced into eitherthe donor or acceptor unit of benzothiadiazole-quaterthiophene polymersto generate F-D and F-A, respectively. This regioselective fluorinationinduced distinct molecular conformations and electronic distributions,thereby influencing charge transport and charge transfer with moleculardopants. Consequently, the donor-fluorinated polymer F-D exhibitedenhanced backbone planarity, higher carrier mobility, and a more favorablebalance between carrier concentration and the Seebeck coefficient.Specifically, doped F-D achieved a higher maximum power factor of43.5 μW m^–1 K^–2 than F-A(23.0 μW m^–1 K^–2) and deliveredsuperior thermoelectric performance, with figures of merit of 0.056for F-D and 0.026 for F-A. Notably, F-D also exhibited greater airstability, retaining 82% of its initial power factor after 7 daysunder ambient conditions, compared with 39% for F-A. Collectively,these results highlight the critical role of fluorinated regioisomerismin determining the thermoelectric performance and air stability ofD–A conjugated polymers, thereby providing valuable guidancefor the molecular design of advanced OTE materials.

Zeolitic imidazolateframework (ZIF) biocomposites are widely studiedfor their potential in biocatalysis and biomedicine. However, theirpreparation is highly sensitive to precursor composition, concentration,washing conditions, and operator-dependent handling procedures. Here,we combine a semiautomated syringe-pump system, high-throughput samplepreparation, and digital data visualization to map synthesis–structure–propertyrelationships in ZIF biocomposites. A programmable four-syringe pumpplatform was used to systematically prepare 360 distinct samples intriplicate, yielding 1080 samples. The investigated synthetic parameterswere relative amounts of metal, ligand, protein, the total precursorconcentration, and the washing protocol. Structural, chemical, andfunctional characterization yielded a data set of ∼2250 entriescomprising crystalline-to-amorphous ratios, IR-based protein-to-frameworkratios, encapsulation efficiency, and loading capacity. We note thatexploring such a large data set manually can be challenging and thatcurrent static visualizations can hide meaningful trends. With theaim of enabling a customized and interactive exploration of the data,we designed the ZIF Biocomposite Explorer App (ZIF-BEA), which supportsuser-defined navigation in the space of the variables, providing directaccess to experimental data and material properties. We anticipatethat integrating large experimental data sets with interactive digitalplatforms may expedite the design of MOF-based biocomposites, whileproviding a transferable tool for the exploration of other classesof functional materials.

Superionic conductors exhibit exceptionally high ionicconductivity,making them crucial in next-generation solid-state batteries and solidoxide fuel cells. However, their scarcity remains an obstacle to practicalapplications, and current discovery strategies are largely guidedby chemistry-specific design principles. Here, we observed that thelow-temperature phases of a few well-known superionic conductors containinterstitial sites that possess nearly identical local chemical environmentsto those of lattice sites, which become activated at elevated temperaturesand facilitate ion transport. Based on this insight, we proposed asymmetry-based strategy to identify materials containing symmetry-equivalentinterstitial sites that satisfy similarity in local chemical environments.By integrating high-throughput screening with molecular dynamics simulationsbased on a universal machine-learning force field, we identified five,four, and three new oxygen-based, lithium-based, and sodium-basedsuperionic conductors with ionic diffusion properties comparable toleading materials, respectively. Diffusion pathway analysis confirmsthat these interstitial sites contribute to forming interconnectedconduction channels at elevated temperatures. Our work introducesa general design principle and a computationally efficient approachfor accelerating the discovery of superionic conductors.

Many of the materialsunder consideration as battery electrodesare known to exhibit polarons─charge carriers localized throughpolarizing their environments, which are unfortunately quite costlyto tackle by theory. Next to costly ab initio methods and geometryoptimizations, the main problem is the sheer number of possible configurationspolarons can adopt in a material. This problem is exacerbated by symmetry-breakingdefects such as oxygen vacancies ubiquitous in oxide materials. Fortunately,a majority of polaron configurations tend to be too high in energyto ever be adopted at normal operating temperatures. In this work,we therefore present a data-driven approach based on gradient-boosteddecision trees as a descriptor for relative polaron energies. We demonstratethe efficacy of this approach to weed out those configurations thatare energetically unlikely in three simulation cells of defected spinelLithium₄Titanium₅Oxygen₁₂ (LTO).The first two cells differ by their 16d-site occupational disorderand the position of the oxygen vacancy, which in both cases leadsto the formation of two polarons in the cells. In contrast, the thirdsimulation cell contains an extra lithium ion, which leads to threepolarons. Our approach allows us to reduce the number of necessaryfirst-principles calculations by roughly two-thirds. It can easilybe adapted to other materials and simulation cells, greatly speedingup their theoretical treatment.

Sulfide-based lithium-ionsolid electrolytes are promisingcandidatesfor solid-state batteries due to their high ionic conductivities,although they typically exhibit high moisture sensitivity. Li₄SnS₄ has recently attracted scientific interestbecause it exhibits higher moisture resistance than most other sulfideelectrolytes. Two orthorhombic Li₄SnS₄ polymorphs(α and β) are known, yet their temperature-dependent phasebehavior remains unexplored. Differential scanning calorimetry andtemperature-dependent powder X-ray diffraction revealed that α-Li₄SnS₄ transitions to β-Li₄SnS₄ at 96 °C. Furthermore, we identified a second, previouslyunknown reversible phase transition from β-Li₄SnS₄ to a new γ-polymorph at 196 °C. Other phase transitionsfrom −150°C to 1000°C were not identified. All polymorphscrystallize in space group Pnma (no. 62) and featureidentical zig-zag-like arrangements of SnS₄^4– tetrahedra. The main structural differences lie in the orderingof the lithium substructure. By combining temperature-dependent powderX-ray and neutron diffraction with high-temperature ⁷Liand ¹¹⁹Sn NMR as well as Raman spectroscopy, we show thatLi₄SnS₄ transitions from the lithium-vacancy-disorderedα-phase to the ordered β-phase and finally to the disorderedγ-Li₄SnS₄. Using electrochemical impedancespectroscopy, we measured ionic conductivities from 10^–6 S cm^–1 to 10^–1 S cm^–1 between 25 °C to 220 °C. Conductivity changes are gradual,consistent with the subtle structural variations among all polymorphs.

In-situ electrochemical spectroscopicellipsometry(EC-SE) can enable real-time monitoring of optical properties andthickness changes of surfaces and thin films. This method can providea broad range of information on the evolution of the microenvironmentof an electrode during electrochemical reactions. However, to avoidmodeling artifacts, accurate data analysis is critical. Here, we outlinekey steps in data analysis that can help prevent overfitting and misinterpretationof results. For example, determining the refractive index of the electrolyteat the air/electrolyte interface, along with measurements of the electrode’sdielectric data in dry conditions, can yield more accurate resultsthan simultaneous fitting of all parameters for the electrolyte andelectrode. We also present detailed modeling strategies tailored tofitting in-situ cyclic voltammetry (CV) data on varioustypes of thin films, by providing two distinct examples: the thicknesschange of catalyst polymer films due to swelling by the electrolyte,and the simultaneous change in thickness and optical properties ofTi₃C₂T_x MXene filmsdue to both reversible (electrochromic effect) and irreversible (degradation)processes. These details can help guide the informed selection ofmodels in similar conditions by providing practical guidelines. Thestep-by-step approach to modeling can be more broadly adopted to enhancethe accuracy and reproducibility of EC-SE experiments for interfacialstudies relevant to energy conversion and storage, as well as otherelectrochemical reactions.

The inherent flexibility and processability of polymersmake themindispensable for next-generation flexible electronics, yet theirintrinsic electrical properties remain critical bottlenecks. A powerfulworkaround lies in hybrid materials that challenge this bottleneckby merging organic and inorganic components to unlock unprecedentedfunctionalities through synergies. Beyond composition, area-selectivefunctionalization is equally critical to the practical constructionof electronic devices. Here, we demonstrate infiltration of ZnO intoa lithographically patterned poly(ethylene terephthalate) (PET) matrix,locally transferring the pattern to the polymer subsurface. Followingour approach of area-selective vapor-phase infiltration (AS-VPI),both the region and the depth of infiltration become controllable,even to the micrometer scale. With linear patterns, we demonstrateanisotropic electrical conductivity, showing a difference in resistanceof more than 7 orders of magnitude between directions parallel andperpendicular to the infiltrated pattern. The benefit of using VPIto embed ZnO within the polymeric matrix rather than simply coatingthe surface is demonstrated by the preservation of electrical resistanceafter bending and deliberate scratching of the sample, as conductivepathways in the subsurface maintain current flow. AS-VPI is thereforedemonstrated as an effective strategy for producing electrically functionalizedpolymers suitable for the design of flexible and wearable electronicdevices.

The intracellular delivery of functional proteins remainsa majorchallenge due to the impermeability of the plasma membrane and inefficientendosomal escape. Here, we report a membrane-intercalating conjugatedoligoelectrolyte (MI-COE, BBTN) that enables near-infrared (NIR)-triggereddirect cytosolic protein delivery through molecular photoporation.Distinct from conventional carriers that require complex formulationsand rely on endocytic uptake, BBTN spontaneously inserts into thelipid bilayer, enabling localized NIR-responsive membrane modulation.Upon mild NIR irradiation, BBTN induces transient and reversible membranepermeabilization, facilitating the direct transport of proteins intothe cytosol while maintaining high cell viability. This loading-freeplatform exhibits broad compatibility with diverse proteins, includingfluorescent proteins (GFP and R-PE), enzymes (β-galactosidaseand horseradish peroxidase), and therapeutic proteins (caspase 3 andRNase A), while preserving their biological functions after delivery.Furthermore, BBTN enables NIR-II fluorescence imaging-guided proteindelivery in vivo and enhances the therapeutic efficacy of RNase Aagainst solid tumors. These results establish membrane-intercalatingconjugated oligoelectrolytes as a versatile materials platform forintracellular macromolecular delivery and biomedical applications.