Saad A. Khan

We report the fabrication of a conductive nanofibrous aerogel (NFA) by coating polypyrrole (PPy) onto a mechanically resilient polyacrylonitrile/polyvinylpyrrolidone (PAN/PVP) NFA framework via low‐temperature oxidative polymerization. The PPy forms a conformal layer on individual nanofibers, generating continuous three‐dimensional conductive pathways. The resulting hybrid combines the robust framework of the NFA with the conductivity and chemistry of PPy, enabling stable pressure sensing and effective sorption of anionic contaminants from water. Systematic variation of the oxidant‐to‐monomer ratio and polymerization time reveals how PPy coating morphology and loading influence the sensing and adsorption performance. Optimized samples exhibit a sensitivity of 5 kPa ^{− 1} and a gauge factor of 0.32 within 0%–5% strain for low‐pressure piezoresistive sensing. When integrated into a wearable format, the NFA enables real‐time motion detection, while tolerating large compressive strains and maintaining shape recoverability up to 70% under repeated loading. It also exhibits strong affinity for metanil yellow, an azo dye commonly found in industrial effluents that adversely impacts aquatic ecosystems. Removal efficiencies are maintained across varying pHs (3–9), with maximum adsorption of ∼98 observed at pH 5. Adsorption is reversible, with comparable uptake sustained over multiple cycles. Overall, the PPy‐coated NFA establishes a tunable, multifunctional platform for both pressure sensing and water remediation.

Metal-organic framework (MOF)-fiber composites integrate MOF's tunable functionality with flexible fibrous matrices for applications in various areas, including water purification, filtration, gas adsorption, and sensing to catalysis. Conventional techniques for the fabrication of MOF-fiber composites often involve the use of harsh organic solvents and complex time-intensive processing steps and can result in composites with poor MOF adhesion. In our work, we address these challenges by developing a simple and solvent-free air-spray coating method for the fabrication of MOF-fiber web composites. We employ bicomponent nonwovens as our fibrous substrate, consisting of a shell/core structure with polypropylene in the core and poly(ether-block-amide) in the shell. MOF particles, zeolitic imidazolate framework-8 (ZIF-8) and UiO-66-NH₂, are spray-coated onto a nonwoven fabric using compressed air in 2, the air-spray coating method is adaptable for other mechanically and thermally stable MOFs and various fibrous and nanofibrous structures. Overall, this work presents a scalable, simple, and solvent-free approach for MOF-fiber composite synthesis with broad applicability.

There is a critical need for innovative materials that offer efficient chemical filtration and detoxification of organophosphonates (OPs), pesticides, and other toxic industrial gases. In this study, a versatile method is introduced for fabricating 3D hierarchically porous mechanically stable nanofibrous aerogel (NFA)‐MOF composites with MOF mass fraction exceeding 80 wt.%, designed for enhanced detoxification. Mesoporous Zr‐MOF (UiO‐66‐NH ₂ ), synthesized through a mild solvothermal process with cocamidopropyl betaine (CAPB) surfactant as a template, is combined with PAN/PVP nanofibrous dispersions to create composite NFAs. By adjusting CAPB concentration, MOF mesoporosity is tuned, achieving a maximum surface area of 1000 m ² g ⁻¹ with 0.5 g CAPB. Composites containing UiO‐66‐NH ₂ show effective hydrolysis of the DMNP simulant and degradation of chemical warfare agents (CWAs) such as soman (GD) and sulfur mustard (HD). The versatile mixing strategy is extended to incorporate microporous MOFs such as HKUST‐1 to enhance NFA functionality. Composites with HKUST‐1 effectively adsorb ammonia (NH ₃ ), 2‐chloroethyl ethyl sulfide (CEES), and Cl ₂ while mechanical and adhesion testing confirm that MOF loadings between 50 wt.% and 80 wt.% maintain excellent mechanical integrity. These multifunctional composite NFA offer significant potential as advanced materials for chemical defense, air purification, and environmental remediation, benefiting from a cost‐effective and environmentally friendly synthesis method.

Ultraviolet (UV) radiation exposure poses a potent threat to human health, with skin cancer cases still prevalent. While skin care formulations mitigate the situation, inherent problematic issues, including toxicity and unpredictable rheology, exist in many of these systems. In this study, the functional properties of carboxylated nanodiamond (cND) infused polyacrylic acid (PAA) hydrogels are explored as a potential alternative in terms of their UV protection, rheology control, and lubrication (skin‐feel) properties. cNDs, carbon‐based nanoparticles (≈200 nm), are used because of their innate biocompatible nature, UV filter capacity and tunable surface functional groups allowing for modulating interaction with the PAA matrix. In particular, it is demonstrated these properties can be controlled through varying pH and cND concentration. Dynamic rheology and confocal fluorescence microscopy reveal different degrees of microstructural reinforcement enabled by changing the nature of polymer‐cND and interparticle interactions above (pH 5.5) and below the pKa (pH 4.1) of carboxyl groups. Tribological experiments in contrast, suggest that lubrication properties to be primarily governed by microgel particles at either pH. Most importantly, UV absorption and simulated irradiation studies show these systems to be photostable with broad‐spectrum UV attenuation capacity rivalling that of commercial systems, while preserving gel microstructure after prolonged UV irradiation.

This study investigates the self-assembly of hybrid poly(amidoamine)-peptide dendrimers (DendriPeps) into shear-responsive vesicle-like structures with nanometric thickness, called "Nanocoats", that are capable of encapsulating nano- and microscale particles. To assess the material-agnostic coating power of DendriPeps, we tested the formation of Nanocoats on a variety of synthetic and biological substrates, including polystyrene nanoparticles, poly(N-isopropylacrylamide) microgels, gallium-indium liquid metal nanodroplets, and bacteriophages and lentiviruses. Specifically, we utilized spectroscopic and microscopic techniques to monitor the reversible assembly of Nanocoats on the surface of the particles upon controlling the shear stress of the surrounding aqueous phase. Furthermore, we evaluated the use of Nanocoats as a glue mediating the formation of particle clusters, whose size, in terms of the number of particles and coating thickness, can be dynamically controlled by adjusting the shear stress. Finally, we harnessed the reconfigurability of DendriPep Nanocoats to develop vectors for the shear-controlled delivery of a bioactive payload. To that end, we achieved the controlled release of the antibacterial peptide polymyxin B from DendriPep-coated microgels by applying shear stresses of 0.5-1 Pa. These results demonstrate the potential of DendriPeps to develop reconfigurable systems for biomedical applications that leverage localized shear gradients.

This study explores the synthesis and functionality of mesoporous UiO-66-NH₂ metal-organic framework (MOF) impregnated cellulose diacetate (CDA)-silica hybrid nanofibrous aerogels (NFAs) for selective CO₂ capture. Mesoporous MOFs generally outperform microporous MOFs for CO₂ capture, while NFAs provide a lightweight, highly porous material platform consisting of a three-dimensional (3D) network of interlinked nanofibers, offering both mechanical strength and a larger surface area. We exploit the attributes of these candidate materials by producing CDA-silica@UiO-66-NH₂ NFA through a simple freeze-drying process involving a mixture of CDA-silica nanofiber dispersions and mesoporous UiO-66-NH₂ nanoparticles in tert-butanol, avoiding cumbersome pre- or postprocessing typical in aerogel synthesis. The aerogels exhibit a hierarchical porous structure, allow for MOF loadings of up to 80 wt %, and demonstrate remarkable CO₂ adsorption performance, with a direct correlation between MOF content and adsorption efficiency. Notably, an NFA containing 80 wt % MOF achieves a CO₂ uptake of 2.5 mmol/g at 35 °C and atmospheric pressure. The CDA-silica@UiO-66-NH₂ NFA also exhibits a strong preference for CO₂ adsorption compared to N₂ across all pressure levels when exposed to a gas mixture of CO₂ and N₂ in an 85:15 ratio. The CO₂/N₂ selectivity (S_ads) usually calculated by using the ideal adsorption solution theory (IAST) reveals a value of 18.2 at 298 °K for this system. The NFA also displays strong mechanical resiliency including compressibility and fatigue resistance, and MOF integration without detachment during multiple compression cycles. Unlike traditional CO₂ capture materials, our CDA-silica@UiO-66-NH₂ NFA with a combination of high CO₂ selectivity, structural integrity, and ease of fabrication thus offers a potentially scalable solution that addresses both performance and durability in real-world applications.