Higher Water Uptake Research Articles

Mechanical and Morphological Characterization of Hybrid Epoxy Composites Reinforced With Agricultural Waste Fibers

ABSTRACTThis study investigates the mechanical, morphological, and moisture absorption properties of sustainable epoxy composites reinforced with agro‐waste fibers including jute, betel nut husk, corn bark, and sugarcane residues. The composites were fabricated via the hand lay‐up method. Three distinct hybrid composites were fabricated and systematically tested for tensile, flexural, impact, SEM, and water absorption performance. Among the developed composites, the jute + corn bark fiber configuration demonstrated the highest tensile strength (23.60 MPa), flexural strength (21.17 MPa), and strain (8.67%), attributed to superior fiber–matrix adhesion and compact microstructure as validated by scanning electron microscopy (SEM). In contrast, composites reinforced with sugarcane and betel nut fibers exhibited greater porosity, reduced strength, and higher water uptake, highlighting the impact of fiber morphology and interfacial bonding. All samples resisted oil absorption but varied significantly in water and saltwater environments; with the jute + corn bark composite exhibiting the lowest moisture uptake. The findings confirm the viability of underutilized agro‐waste fibers—particularly corn bark—as promising reinforcements in cost‐effective, biodegradable composites suitable for non‐load‐bearing construction, packaging, acoustic insulation, and automotive interior applications. This study is the first to investigate the use of jute fabric reinforced with corn bark fibers in epoxy composites, revealing their superior performance compared to betel nut and sugarcane fibers. The findings advance the field of green materials engineering by offering a sustainable alternative to synthetic composites, particularly suited for moisture‐sensitive and moderately demanding structural applications.

A Polyaromatic Metallotube With a Dual Multi-Functionalization Ability.

Post-functionalization is an advanced, key synthetic method in supramolecular systems, whereas the previous method relies heavily on the substitution on the organic frameworks. Here we report a polyaromatic metallotube capable of dually multi-functionalizing the metal sites in an efficient post-assembly fashion. The Pt(II)-linked tube with tetrachloro groups is prepared from two PtCl2 hinges and two bent bispyridine ligands in high yield. The new metallotube efficiently converts to tetra-substituted tubes by the first multiple functionalization, through the replacement of the chloro groups with various alkynyl groups. The tubular structures before/after the functionalization are unequivocally confirmed by X-ray crystallographic analysis. A resultant tetraammonium-attached Pt(II)-tube exhibits high water solubility and uptake abilities toward spherical and rod-like compounds. The metallotube strongly binds one molecule of fullerene C60 in the polyaromatic cavity yet releases it through the second multi-functionalization by tetrabromination of the metal hinges in a quantitative and reversible manner. Even after Bingel reaction within the tube, sterically demanding bis-substituted fullerenes (>∼80% selectivity) are readily released by the second functionalization. The present method, i.e., the use of simple PtCl2 hinges, will be applicable to wide-ranging metallo-supramolecules to enhance their structural and functional versatilities via post-multi-functionalizations.

A Polyaromatic Metallotube With a Dual Multi‐Functionalization Ability

Abstract Post‐functionalization is an advanced, key synthetic method in supramolecular systems, whereas the previous method relies heavily on the substitution on the organic frameworks. Here we report a polyaromatic metallotube capable of dually multi‐functionalizing the metal sites in an efficient post‐assembly fashion. The Pt(II)‐linked tube with tetrachloro groups is prepared from two PtCl2 hinges and two bent bispyridine ligands in high yield. The new metallotube efficiently converts to tetra‐substituted tubes by the first multiple functionalization, through the replacement of the chloro groups with various alkynyl groups. The tubular structures before/after the functionalization are unequivocally confirmed by X‐ray crystallographic analysis. A resultant tetraammonium‐attached Pt(II)‐tube exhibits high water solubility and uptake abilities toward spherical and rod‐like compounds. The metallotube strongly binds one molecule of fullerene C60 in the polyaromatic cavity yet releases it through the second multi‐functionalization by tetrabromination of the metal hinges in a quantitative and reversible manner. Even after Bingel reaction within the tube, sterically demanding bis‐substituted fullerenes (>∼80% selectivity) are readily released by the second functionalization. The present method, i.e., the use of simple PtCl2 hinges, will be applicable to wide‐ranging metallo‐supramolecules to enhance their structural and functional versatilities via post‐multi‐functionalizations.

Ultra-Tough Single-Network Hydrogels via the Synergy of Defect Elimination and Dual Crosslinking.

Network imperfections, such as multi-dispersed junctions and dangling chains, significantly impair the mechanical performance of hydrogels and elastomers synthesized via free radical reactions (FRRs). Great efforts have been made to introduce sacrificial structures to enhance toughness but cause pronounced hysteresis, leaving a comprehensive solution elusive. Herein, a class of robust single-network hydrogels with minimal imperfections is reported by employing nano-crosslinkers and nano-initiators to produce monodispersed crosslinking points and eliminate dangling-chain defects, in the formation of dual crosslinking of thiolate-Au bond and chemically covalent bond in the network. As a result, the hydrogel achieves a maximum fracture toughness (78 500 J m-2) and fatigue resistance (2480 J m-2), with over 13 and 55 fold increases attributed to the incorporation of dangling chains and dual crosslinking, respectively, without compromising its low hysteresis (0.07). Eliminating dangling chains also improves interfacial contact and osmotic pressure resistance, enabling exceptional underwater self-healing and swelling properties. Even with a high water-uptake of up to 95 wt.%, the swollen hydrogel exhibits stretchability exceeding 2000%, without obvious mechanical degradation after one month of water incubation. This work demonstrates a model system for developing resilient polymers with minimized imperfections derived from FRRs, showing numerous potential applications in underwater applications.

Elaboration of Conductive Hydrogels by 3D Printer for the Development of Strain Sensors

The development of biocompatible, conductive hydrogels via direct ink writing (DIW) has gained increasing attention for strain sensor applications. In this work, a hydrogel matrix composed of polyvinyl alcohol (PVA) and κ-carrageenan (KC) was formulated and enhanced with polyvinylidene fluoride (PVDF) and silver nanoparticles (AgNPs) to impart piezoelectric properties. The ink formulation was optimized to achieve shear-thinning and thixotropic recovery behavior, ensuring printability through extrusion-based 3D printing. The resulting hydrogels exhibited high water uptake (~280–300%) and retained mechanical integrity. Rheological assessments showed that increasing PVDF content improved stiffness without compromising printability. Electrical characterization demonstrated that AgNPs were essential for generating piezoelectric signals under mechanical stress, as PVDF alone was insufficient. While AgNPs did not significantly alter the crystalline phase distribution of PVDF, they enhanced conductivity and signal responsiveness. XRD and SEM-EDX analyses confirmed the presence and uneven distribution of AgNPs within the hydrogel. The optimized ink formulation (5% PVA, 0.94% KC, 6% PVDF) enabled the successful fabrication of functional sensors, highlighting the material’s strong potential for use in wearable or biomedical strain-sensing applications.

The Development of a Coconut-Oil-Based Derived Polyol in a Polyurethane Matrix: A Potential Sorbent Material for Marine Oil Spill Applications

Marine oil spills have caused significant environmental problems. Among the array of clean-up methods, the utilization of sorbents emerges as promising for removing and recovering oil from spills. Developing cost-effective, reliable, and eco-friendly material that efficiently and sustainably removes oil from water is increasingly seen as crucial and pressing. In the present study, we report the development of coco-polyurethane (PU) foam (CCF) through the conventional foaming process using varying amounts of coconut-oil-derived polyol (CODP) in a PU matrix. Characterization of the foams showed an increased ester band with the incorporation of COPD into the polyurethane networks and no direct influence of the cell size distribution on the surface morphology. Furthermore, this study highlighted the increasing CODP in every CCF formulation, showing high oil sorption and low water uptake due to its porous structure. The experimental results revealed that CCF is a potential candidate sorbent for the recovery of spilled oil. This signifies a significant leap towards reducing the dependency on petroleum in developing sorbent materials and advancing sustainable responses to oil spills in marine environments.

Data-Driven Discovery of Water-Stable Metal-Organic Frameworks with High Water Uptake Capacity.

Metal-organic frameworks (MOFs) are promising candidate materials for applications that would benefit from precise chemical patterning, such as desalination, but many MOFs suffer from poor stability in water. In addition to water stability, high water uptake capacity in ambient conditions is expected to be necessary for water-related practical applications of MOFs, motivating large-scale search that can only be achieved computationally. Here, we take a combined machine learning and high-throughput screening approach to identify water-stable MOFs with high water uptake capacities. Starting from a subset of previously curated MOFs with experimentally known exceptionally high stability in water, we explore the effect of linker functionalization with 12 diverse hydrophilic functional groups expected to further tune water uptake. For these 736 MOFs, we use grand canonical Monte Carlo (GCMC) simulations to compute their water uptake capacity. We observe strong positive correlations between MOF pore features (e.g., the largest cavity diameter and volumetric pore volume) and water uptake capacity, although we notice breakdowns of such correlations in MOFs with extremely hydrophobic linkers that repel water molecules despite having large pores. Finally, we develop machine learning models to screen new MOFs simultaneously for water stability and water uptake capacity. From a pool of hypothetical and experimental MOFs, we identify 74 promising materials within the domain of applicability of the machine learning models that are predicted to both be water-stable and have high water uptake.

Toward Enhanced Atmospheric Water Harvesting in Arid Conditions via Mixed-Ligand MOF-Derived Porous Carbon.

The development of solar-driven atmospheric water harvesting (AWH) is critical for synergistically alleviating water scarcity and energy demands in arid regions. However, achieving an efficient water adsorption capacity and rapid photothermal-driven desorption with adsorbents under arid climatic conditions remains a significant challenge. In this work, we design a novel nitrogen-enriched nanoporous carbon (NPCMAF-47) derived from the mixed-ligand metal-azolate framework (MAF-47). NPCMAF-47 exhibits a high water adsorption capacity, rapid adsorption kinetics, and excellent photothermal performance. Under 30% relative humidity, the material achieves a high water uptake capacity of 405 mg·g-1, along with a record-breaking water production rate of 542 mg·g-1·h-1. Notably, under diverse low-humidity arid conditions (≤40% RH), NPCMAF-47 demonstrates a superior overall water adsorption capacity compared to previously reported benchmark AWH adsorbents. Density functional theory calculations reveal a microscopic mechanism through which carbon defects and nitrogen sites synergistically enhance water adsorption by inducing a charge redistribution. This study highlights the defect-nitrogen synergy in carbon design, advancing the development of application materials for sustainable solar-driven AWH.

Improvement of water absorption behavior and mechanical properties of woven jute fiber‐reinforced epoxy composites with waste eggshell filler

Abstract The need for renewable and biodegradable materials has emerged in the last few decades with the awareness of environmental issues and that has led to increased interest in natural fiber‐reinforced composites. Jute fibers, known for their versatility, are abundant, cost‐effective and biodegradable. However, their use is limited by challenges such as low compatibility with polymer matrices and high water uptake. Introducing waste eggshell filler offers a promising solution to enhance mechanical properties and reduce water absorption, while also addressing bio‐waste disposal. This study investigates the impact of eggshell powder fillers on the water absorption and mechanical properties of plain‐woven jute/epoxy composites fabricated via vacuum infusion. Composites with filler ratios ranging from 0 to 5 wt% were subjected to water absorption tests using tap, distilled and saline water, and mechanical tests (tensile, flexural, impact and hardness) under dry and wet conditions. Results indicated that eggshell fillers, up to a 3 wt% ratio, reduced water absorption, with distilled water showing the highest absorption across all samples. Mechanical testing revealed that a 2 wt% filler ratio yielded the optimal performance, exhibiting the highest tensile, flexural and impact strengths in dry conditions, attributed to enhanced load distribution and fiber–matrix bonding. Water immersion significantly deteriorated mechanical properties in all composites, though eggshell fillers mitigated this effect, particularly at 2 wt%. However, filler ratios exceeding 3 wt% led to decreased mechanical performance, likely due to filler agglomeration. This study demonstrates that eggshell powder, a bio‐waste, effectively enhances the water resistance and mechanical strength of jute/epoxy composites, with a 2 wt% filler ratio proving optimal for improved composite performance. © 2025 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Intelligent Hygroscopic Aerogels: Moisture‐Activated Dual‐Mode Switchable Electromagnetic Response

Abstract Intelligent electromagnetic materials featuring controllable and adaptive response characteristics play a vital role in managing complex electromagnetic environments. However, effectively modulating the electromagnetic wave responses from transmission to absorption, and advancing to interference shielding through external stimuli, remains challenging. Herein, a novel moisture‐activated dual‐mode switchable electromagnetic response pattern is demonstrated in hygroscopic lithium chloride@graphene aerogel (LiCl@GA). Benefiting from the ordered hierarchical structures that accelerate vertically oriented moisture convection, the LiCl@GA exhibits ultrahigh water uptake of 4.76 g g−1 and ultrafast water sorption kinetics. This hygroscopic behavior facilitates both switchable electromagnetic wave absorption and interference shielding during water sorption‐desorption processes. The switchable functionality originates from moisture‐driven ionic conduction, where LiCl@GA absorbs ambient moisture to establish highly conductive ionic pathways. From the initial state to low water uptake (0.3 g g−1), the maximum change in minimum reflection loss reaches −70.03 dB. Furthermore, at high water uptake (2 g g−1), the LiCl@GA exhibits switchable electromagnetic interference shielding capability with a broad modulation range from 5.28 to 21.4 dB during water sorption‐desorption cycles. This study unveils previously undiscovered mechanisms for reversibly modulating electromagnetic responses in aligned porous hygroscopic aerogels, expanding their potential applications in electromagnetic interference shielding, smart sensors, and adaptive communication systems.

Block Adamantane‐Contained Poly(Arylether Sulfone)s With Tetra‐Quaternized Side Chains as Anion Exchange Membranes

ABSTRACTAn excellent structural design is critical to the formation of anion exchange membrane (AEM) with a sufficient anti‐swelling and competitive conductivity. Herein, a series of block adamantane‐contained poly(arylether sulfone)s grafting with four‐ionic flexible side chains was prepared for AEM, based on a designed strategy of combining multi‐ionic side‐chain and block skeleton. Then the dense ionic groups within AEMs promote the generation of hydrophilic domains and phase separation morphology, and construct connected ion channels for OH− transport. The as‐prepared AEMs display high conductivity and water uptake (WU) at medium ion exchange capacity (IEC) and low swelling ratio (SR) levels. The representative one of QBAPAS‐10/10 with an IEC value of 2.11 meq g−1 exhibits a WU of 82.5%, SR of 24.3%, and conductivity of 98.47 mS cm−1 at 80°C. Meanwhile, some related characterizations are also conducted on the mechanical property, thermal, and alkaline stability of these AEMs.

Hydrolytically Stable Phosphonate-Based Metal-Organic Frameworks for Harvesting Water from Low Humidity Air.

Harvesting water from air offers a promising solution to the global water crisis. However, existing sorbents often struggle in arid climates due to limitations such as low sorption capacities, hydrolytic instability, slow mass transport, high desorption enthalpy, and costly operation. Phosphonate-based metal-organic frameworks (MOFs), known for their exceptional water stability, have not been extensively explored for water harvesting. This study systematically investigates the performance of STA-12 (M═Co, Ni, Mg) and STA-16 (M═Co, Ni), a series of stable phosphonate-based MOFs, as water sorbents. STA-12 MOFs demonstrate remarkable adsorption at ultra-low humidity (<10%), while STA-16(Co) exhibits a high water uptake capacity of 0.54gg-1 at 10-50% relative humidity (RH) and 0.72gg-1 at 34% RH. Molecular simulations and solid-state NMR identified liquid-like water, critical for harvesting applications, as the key contributor to the superior sorption performance of STA-16(Co). Scalable aqueous synthesis methods are developed, producing tens of grams of MOFs per batch without high-pressure equipment. A prototype device incorporating STA-12(Ni) demonstrated the feasibility of these materials for real-world water harvesting, showcasing their potential to address water scarcity in arid regions.

Response of Gladiolus grandiflorus varieties to planting date: effects on growth, flowering, and vase life

Gladiolus, a bulbous plant native to South Africa, is known for its vibrant and diverse floral colours. To enhance the growth, flowering, and corm production of gladiolus, it is crucial to identify the optimal planting time suited to the climatic conditions of Jammu and Kashmir, India. The present study investigates the response of Gladiolus grandiflorus varieties to planting date: effects on growth, flowering, and vase life. In Experiment I, early planting on October 15 significantly improved vegetative traits, with the variety ‘Oscar’ showing superior performance in terms of plant height (129.78 cm), number of leaves per plant (8.96), number of florets per spike (15.22), spike length (93.44 cm), and spike weight. Oscar variety planted in October gave the tallest plant, highest leaf number, and corm yield. Additionally, chlorophyll content was highest in variety ‘White Prosperity’ (0.92 mg g⁻¹ fresh weight) when planted in October. Experiment II focused on postharvest management, demonstrating that specific holding solutions, particularly sucrose supplemented with acetic acid, significantly increased the vase life of cut spikes, with ‘Oscar’ achieving a vase life of 12.30 days. The highest water uptake (135.30 mg) was observed in spikes planted in October, and a strong positive correlation was noted between water uptake, electrical conductivity (EC) of the holding solution, and chlorophyll content. In conclusion, it is recommended to plant gladiolus varieties, particularly ‘Oscar’, in mid-October in Jammu and Kashmir to maximize growth and flowering, and to use sucrose supplemented with acetic acid as a holding solution to extend vase life and improve postharvest quality.

Non‐Porous Hydrogel Scaffolds for Locoregional Chemotherapy: A One‐Pot Synthesis Approach

Abstract Although surgery is common in the treatment of solid tumors in cancer, the risk of recurrence after operation is high in malignant tumors. This study focuses on fabricating doxorubicin‐loaded, non‐porous POEGMEMA (Poly(oligo(ethylene glycol) methyl ether methacrylate)) and PLGA (Poly(D,L‐lactide‐co‐glycolide))/POEGMEMA scaffolds for locoregional chemotherapy. Polymer synthesis, hydrogel formation, and drug‐loading processes are performed using a one‐pot approach. The scaffolds were characterized by mechanical, swelling, degradation, and release tests. 10% PLGA content, causes PLGA/POEGMEMA scaffolds to give a 2.5 times lower swelling ratio and sixfold higher compression stress than POEGMEMA scaffolds. Also, PLGA addition causes an increase in the biodegradation half‐life of POEGMEMA‐based hydrogel scaffolds. While PLGA/POEGMEMA scaffolds exhibit a degradation‐dependent release profile, POEGMEMA scaffolds give a burst release due to their high water uptake ratio. The burst release behavior of POEGMEMA scaffolds causes a high antiproliferative effect (viable cells: 5–10%) against HT‐29 and MCF‐7 cancer cells in the short term. In contrast, the controlled and sustained release profile of PLGA/POEGMEMA scaffolds shows an antiproliferative effect (viable cells: 50–60%) dependent on the release ratio. This hydrogel scaffold platform allows tuning physical and functional properties to deal with diverse physiological conditions at the region after tumor surgery for locoregional chemotherapy.

High‐Efficiency Atmospheric Water Harvesting and Irrigation Recycling in Greenhouse Using Hygroscopic Composite Gels

Abstract The pressing need to address the water‐food nexus, exacerbated by climate change and a rapidly growing population, calls for innovative approaches in agricultural water management. This study introduces a pioneering device, the side window recycler (SWR), which is specifically designed for greenhouses to increase water‐use efficiency. Central to the SWR is a multi‐component, interconnected hygroscopic porous gel named LHPE, which boasts significant scalability and robust adhesion properties. When synthesized through an optimized process, LHPE boasts a high water uptake of up to 4.06 gwater gsorbent−1, supporting rapid water release during desorption. The SWR utilizes this advanced gel to capture water vapor escaping from greenhouse side windows, converting it into irrigation water through electrically heated desorption. Within greenhouse trials, SWR achieved a water recovery rate of 5015.6 g m⁻2 and a water‐saving efficiency of 78.78%, significantly enhancing crop yields by as much as 120%. By integrating sustainable water recycling into agriculture, SWR addresses the global water scarcity crisis and represents a transformative advance in greenhouse water efficiency, poised for impactful adoption in water‐intensive practices worldwide.

Dual exsolution in silver‐functionalized layered and cubic perovskite oxides

Abstract In this work, exsolution is achieved from both the A‐site and B‐site of (BaGd0.8La0.2)1‐xAgxCo2O6‐δ and (BaLa)1‐xAgxCoFeO6‐δ (x = 0.04, 0.1, and 0.2) perovskites prepared via solid‐state sintering. Through synchrotron radiation powder X‐ray diffraction and X‐ray absorption spectroscopy techniques, the chemical composition of the nanoparticles was determined to constitute both Ag and CoO. Microstructural studies were done using scanning electron microscopy with varying sizes and shapes of nanoparticles present for respective annealing atmospheres and temperatures. By applying a numerical model to experimental data, it was also established that the changes in enthalpy for oxygen vacancy formation decrease with an increase in silver dopant. From thermogravimetric measurements, the single (BaLa)0.95Ag0.10CoFeO6‐δ perovskite had relatively higher water uptake than the layered (BaGd0.8La0.2)0.95Ag0.10Co2O6‐δ perovskite. The total electrical conductivity done in dry and wet conditions decreased with an increase in temperature in the range of 300–800°C for both layered and single perovskites. The results obtained from electrical conductivity relaxation measurements of (BaGd0.8La0.2)0.95Ag0.10Co2O6‐δ with nanoparticles exhibit increased oxygen reduction reaction activity than (BaLa)0.95Ag0.10CoFeO6‐δ with nanoparticles.

Evaluation of the Cultivation of Three Halophytic Plants Under Half-Strength Seawater Aquaponics

Water scarcity poses a significant threat to food security, particularly in coastal, arid, and semi-arid regions. To address this challenge, a half-strength seawater aquaponics system (approximately 250 mM NaCl) was developed to cultivate halophytes. This study investigated the growth performance of three halophytic species—ice plant, romeritos, and sea asparagus—to assess their adaptability and optimal agronomic management in a saline aquaponics setting. After rearing tilapia in half-strength seawater, four treatments were applied to the rooting medium: untreated half-strength seawater aquaculture rearing water (HSW) (C), pH-adjusted (5.5) HSW (pH), pH-adjusted (5.5) HSW supplemented with additional nutrients (pH+S), and a standard nutrient solution (NS). The findings revealed that ice plant growth was significantly enhanced by pH adjustment and nutrient supplementation, leading to improved water and potassium absorption. Conversely, romeritos and sea asparagus demonstrated stable growth across treatments, likely due to high sodium accumulation and consistent water uptake despite elevated salinity. Sea asparagus exhibited dependency on high salinity, while romeritos showed increased phosphorus accumulation with nutrient supplementation. This study suggests that while pH adjustments favor ice plant growth, romeritos and sea asparagus are resilient across diverse salinity conditions, highlighting saline aquaponics as a viable approach for halophyte cultivation in water-scarce environments.

Self-Healing 2D Anion-Organic Frameworks for Low-Temperature Water Release.

Molecular frameworks have recently shown a great potential in atmospheric water harvesting, in which the water release at low temperatures is challenging. Anion-organic frameworks based on anion-coordination chemistry are presented herein to meet this challenge. These frameworks are prepared as tubular single crystals in pure water from the in situ protonation and crystallization of pyridine-terminated triphenylamine derivatives with hydrochloric or hydrobromic acid. They possess a 2D honeycombed porous structure and carry halogen anions confined within 1D hexagonal nanochannels with a modular size of 1.7-2.3 nm. They exhibit a high water uptake of up to 0.87 g g-1 and a water release onset temperature as low as -90 °C. The water uptake and release induce significant changes in the crystal morphology and absorption and emission properties of these framework crystals, providing a visual indication of their hydration states over a wide temperature range. The kinetics of dehydration at subglacial temperatures is successfully determined by emission spectral shifts. These framework crystals show a high water-stability and can be used for repeated water capture and release thanks to a rapid and robust self-healing capability. This discovery opens opportunities for the design and synthesis of flexible and self-healing frameworks for porosity-related applications.

Self‐Healing 2D Anion‐Organic Frameworks for Low‐Temperature Water Release

Abstract Molecular frameworks have recently shown a great potential in atmospheric water harvesting, in which the water release at low temperatures is challenging. Anion‐organic frameworks based on anion‐coordination chemistry are presented herein to meet this challenge. These frameworks are prepared as tubular single crystals in pure water from the in situ protonation and crystallization of pyridine‐terminated triphenylamine derivatives with hydrochloric or hydrobromic acid. They possess a 2D honeycombed porous structure and carry halogen anions confined within 1D hexagonal nanochannels with a modular size of 1.7–2.3 nm. They exhibit a high water uptake of up to 0.87 g g−1 and a water release onset temperature as low as −90 °C. The water uptake and release induce significant changes in the crystal morphology and absorption and emission properties of these framework crystals, providing a visual indication of their hydration states over a wide temperature range. The kinetics of dehydration at subglacial temperatures is successfully determined by emission spectral shifts. These framework crystals show a high water‐stability and can be used for repeated water capture and release thanks to a rapid and robust self‐healing capability. This discovery opens opportunities for the design and synthesis of flexible and self‐healing frameworks for porosity‐related applications.

Development of biodegradable chlorhexidine-functionalized polyurethane nanofibers for antimicrobial applications

Conventional chlorhexidine (CHX) formulations provide a short-term antibacterial effect which necessitates repeated application with compromised patient compliance. There is an unmet demand for controlling CHX delivery at local infections or operative sites to comply with specific therapeutic needs. We propose herein CHX-functionalized nanofibers (NFs) fabricated using a series of poly(ethylene glycol)-poly(caprolactone) (PEGCL) amphiphilic copolymers with different molecular weight (MW) and hydrophilicity as an approach to sustaining CHX release. Physicochemical characterization indicated poly(ether-ester-urethane) structures with different MW (85450-338400), relatively high water uptake capacity (150-230 % at 6 h), biodegradability, and cytocompatibility. Electrospinning of organic copolymer solutions containing 0.5 % CHX resulted in NFs with a 263-205 nm mean diameter, 77.3-85.4 % entrapment efficiency, and molecular drug distribution with no discernible drug-copolymer interaction. Drug release from NFs at pH 7.4 and pH 4.5 took place according to different patterns depending mainly on the copolymer MW, hydrophilicity, and content of the PEG segment as well as the medium pH. Multi-hour to multi-day CHX release could be achieved featuring a range of burst and sustained release phases to meet antimicrobial needs ranging from immediate short-term effects at higher drug concentrations to sustained antimicrobial effects in longer-term applications.