Hybrid Sponge Research Articles

Ionic imprinted CNTs-chitosan hybrid sponge with 3D network structure for selective and effective adsorption of Gd(III)

From economical and environmental standpoint, it is very meaningful for selective recovery of Gd(III) via adsorption from the real waste solution. At present, conventional adsorbents are impeded by poor adsorption capacity, low selectivity, complicated preparation and eco-pollution. To this end, a novel imprinted CNTs-chitosan hybrid sponge (COOH-CNTs/CS-IIS) with 3D network structure was fabricated via easy polymerization-lyophilization method for selective adsorption of Gd(III). The imprinting sites dispersing on the surface of channels in COOH-CNTs/CS-IIS can achieve the selective adsorption to Gd(III) and improve adsorption capacity. The combining of biomass chitosan sponge with oxidized CNTs not only further enhances the adsorption capacity and mechanical strength of COOH-CNTs/CS-IIS but also actualizes its rapid retrieval by the squeeze of elastic sponge. Systematic adsorption tests indicate that COOH-CNTs/CS-IIS has a maximum adsorption capacity of 71.95 mg g−1, and can adsorb 88.9% of the ultimate adsorption within 60 min. The selectivity tests show that COOH-CNTs/CS-IIS exhibits preferential adsorption for Gd(III) with a distribution coefficient of 0.656 L g−1. Furthermore, COOH-CNTs/CS-IIS has excellent regeneration performance. Considering its cost-effectiveness, eco-friendliness, user-friendliness, easy preparation and favorable adsorption performance, COOH-CNTs/CS-IIS holds great promise in selective recovery of Gd(III) from the real waste solution.

One-pot facile synthesis of PDMS/PDMAEMA hybrid sponges for surfactant stabilized O/W emulsion separation.

Hydrophobic/oleophilic sponges are excellent absorbent materials for oil contaminant removal. However, the application is limited in dealing with surfactant stabilized O/W emulsions. The water in the emulsion isolates the contact between the sponge and oil droplets. Consequently, the oil absorption efficiency is not ideal. Herein, to improve the oil absorption efficiency from anionic surfactant stabilized O/W emulsions, water responsive hybrid sponges were reported. To prepare such sponges, water soluble poly(N,N-dimethylaminoethylmethacrylate) (PDMAEMA) was introduced into polydimethylsiloxane (PDMS) sponges using table salt as a template and multi-walled carbon nanotubes (MWCNTs) as mechanical reinforcement in a one-pot method. Upon contact with an O/W emulsion, the water soluble PDMAEMA chain rose to the surface of the sponge, turning the hydrophobic surface into hydrophilic. Next, the tertiary amine groups in PDMAEMA ionized in water and carried positive charges which would cause the coagulation of oil droplets. Finally, the coagulated oil droplets were absorbed immediately by the oleophilic inner part of the sponge through the wicking effect. As a result, a Janus interface was generated in situ and sustained. Such material design synergistically contributed to a satisfactory hexadecane (HD) absorption efficiency of 178 ± 4% in 25 min. In contrast, the PDMS-MWCNT1.0% sponge could only absorb 9.8 ± 0.2% HD. Moreover, these sponges also presented robust mechanical performance and reusability, offering a new route for oil/water separation and oil pollution remediation in open water.

Multifunctional hybrid sponge for in situ postoperative management to inhibit tumor recurrence.

Disseminated tumor cells in bleeding and residual tumor cells in the resection tumor site are the primary factors that result in tumor recurrence after surgery. Safe and efficient local implantation of the drug depot system into the resection cavity to inhibit tumor recurrence would be of great benefit to reduce the mortality of postoperative patients. Here, a sandwich-like doxorubicin-triptolide-loaded fiber/(chitosan/gelatin) sponge, DTF/CGS, is fabricated, combining hemostatic, antibacterial, and chemotherapeutic capability. The CGS obtained via freeze-drying can efficiently prevent bleeding; meanwhile, the metastatic residual tumor cells are stuck with the clotted absorbed blood. Subsequently, dual drugs released from the electrospun fiber can further kill the stuck tumor cells in CGS and the disseminated tumor cells to significantly inhibit the tumor recurrence. This antitumor recurrence strategy by immediately implanting a multifunctional hybrid sponge for in situ postoperative management may possess great potential for preventing tumor recurrence.

Adsorptive and responsive hybrid sponge of melamine foam and metal organic frameworks for rapid collection/removal and detection of mycotoxins

Mycotoxins have been regarded as one of the most severe threatens to food safety and environment, however, conventional detection methods are limited by low collection efficiency and tedious detection procedures. In this work, adsorptive and responsive hybrid sponge was prepared by integrating porous fluorescent Zr-LMOF (luminescent metal-organic framework) and robust melamine sponge for simultaneous collection/removal and detection of mycotoxins. The hybrid sponge achieved high load capacity of 15.8 mg g−1 within 10 min and worked well in a wide range of pH and temperatures. The fluorescence of the hybrid sponge was efficiently quenched by AFB1 in the aqueous water in 10 min due to the hierarchical pore structure enabled absorbent-target interaction. This simple, robust and low-cost dual functional hybrid sponge enabled the detection with relatively low LOD of 1.6 ppb and wide linear range of 31.2 ppb-15.6 ppm. Additionally, AFB1 in water was quickly absorbed by the Zr-LMOF crystals on the melamine microfibers with the removal efficiency reached as high as 90%. The removal efficiency towards other mycotoxins including aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1 and ochratoxin A also reached 80%. Overall, this low-cost, robust and elastic hybrid sponge has great potential in the construction of novel sensors for practical applications to ensure environmental and agricultural safety.

MIL-100(Fe)-derived carbon sponge as high-performance material for oil/water separation

High hydrophobic and oleophilic hybrid porous sponges were prepared by coating low cost commercial melamine-formaldehyde sponges with a metal-organic framework (MOF) derived porous carbon. A mesoporous metal-organic framework MIL-100(Fe), obtained under mild conditions, was used as precursor material to obtain highly porous carbon, which was incorporated by a simple method onto the three-dimensional skeleton of the commercial sponge. Due to the porous structure and high hydrophobic (water contact angle of 145 ± 6°) and oleophilic (oil contact angle of 0°) properties of the developed hybrid sponges, they were successfully applied for oil-water separation. The carbon coated sponge exhibited excellent selectivity, good absorption capacity of different oils and the advantage of being easily regenerable. Moreover, the hybrid sponge was used in conjunction with a vacuum system for continuous separation of oil pollutants from the water surface showing excellent oil-absorption abilities even in the case of real saltwater samples.

The preparation of nano-MIL-101(Fe)@chitosan hybrid sponge and its rapid and efficient adsorption to anionic dyes

The polymer adsorbents in the sponge form have the porous structure and high elasticity that endow them with good adsorption capacity and recyclability. The immobilization of nano-materials in the sponges can improve their adsorption properties evidently. The nano-MIL-101(Fe)@chitosan(CS) hybrid sponge was prepared by freeze-drying method. Characterization results indicated that rhombic nano-MIL-101(Fe) particles were uniformly dispersed throughout the hybrid sponge. The hybrid sponge showed higher efficiency for the adsorption of anionic dyes compared with the pristine CS sponge. The maximum adsorption capacity of MIL-101(Fe)@CS sponge for Acid Red 94 reached 4518 mg/g and the rapid suction experiments on different dyes showed that the hybrid sponge could be used as a filter for the quick removal of anionic dyes in low concentration solution.

Enhanced Sensitivity of Capacitive Pressure and Strain Sensor Based on CaCu3Ti4O12 Wrapped Hybrid Sponge for Wearable Applications

AbstractPressure sensors with highly sensitive and flexible characteristics have extensive applications in wearable electronics, soft robotics, human–machine interface, and more. Herein, an effective strategy is explored to enhance the sensitivity of the capacitive pressure sensor by fabricating a dielectric hybrid sponge consisting of calcium copper titanate (CaCu3Ti4O12, CCTO), a giant dielectric permittivity material, in polyurethane (PU). An ultrasoft CCTO@PU hybrid sponge is fabricated via dip‐coating the PU sponge into surface‐modified CCTO nanoparticles using 3‐aminopropyl triethoxysilane. The overall results show that the –NH2 functionalized CCTO attributes proper adhesion of CCTO with the –OCN group of the PU to enhance interfacial polarization leading to a high dielectric permittivity (167.05) and low loss tangent (0.71) beneficial for flexible pressure sensing applications. Moreover, the as‐prepared CCTO@PU hybrid sponge at 30 wt% CCTO concentration exhibits excellent electromechanical properties with an ultralow compression modulus of 27.83 kPa and a high sensitivity of 0.73 kPa−1 in a low‐pressure regime (<1.6 kPa). Finally, pressure and strain sensing performance is demonstrated for the detection of human activities by mounting the sensor on various parts of the human body. The work reveals a new opportunity for the facile fabrication of high performance CCTO‐based capacitive sensors with multifunctional properties.

A hybrid sponge with guanidine and phytic acid enriched surface for integration of antibiofouling and uranium uptake from seawater

In seawater, biofouling caused by marine organisms’ adhesion on the surface of adsorbent would lead to a significant decrease in adsorption property. Herein, a poly (guanidine-hexamethylenediamine-phytic acid) hybrid sponge (PGHPA-PDF-MF) was synthesized for integration of uranium uptake from seawater with antibiofouling property. The PGHPA-PDF-MF sponge exhibited the superhydrophilicity and retained nearly 29 kPa of compression stress after 1000 cycles. Noteworthy, the PGHPA-PDF-MF sponge showed obviously anti-algae growth behavior (88% cell death rate) due to its guanidine and phytic acid groups, as well as inhibit adhesion of algae (Nitzschia) and mussels (Mytilus edulis) by the co-effect of its function groups, 3D porous sponge structure and superhydrophilic surface. The saturated U-uptake amount of PGHPA-PDF-MF sponge was high as 531.9 mg/g at nearly seawater pH (~8.0). At 5th cycle, the sponge still had superior reusability and maintained a high removal amount (200.7 mg/g). The uranium uptake amount of PGHPA-PDA-MF sponge was 44.75 mg/g with 90.9% of removal efficiency in uranium and Nitzschia contained artificial seawater at 7 days. Furthermore, more than 80% of uranium removal rate for the PGHPA-PDF-MF sponge in natural seawater (Bohai, China) also showed its great potentiality for actual application.

Nonlinear optical properties of Sponge Si/Au nanoparticle

Plasmon sponge nanostructures have occupied a special role in the field of plasmonics and nanophotonics: sensors and advanced source of white emission. If the pores of a golden spongy nanostructure are filled with silicon, the result will be a promising source of broadband radiation with high efficiency due to the localization of the field by a structure with a high surface-to-volume ratio. This paper presents the results of photoluminescence generation with multiphoton absorption and second-harmonic generation obtained from hybrid sponge Si/Au nanoparticles. The particles have been fabricated by femtosecond laser ablation at room temperature in the air. Experiments have shown the ability to generate broadband photoluminescence in the range of 500 – 800 nm (0.93 eV). The obtained results can be applied for creation of white light luminescent metasurfaces and advanced nanophotonic spectroscopy devices.

Keratin/Hydrotalcites Hybrid Sponges as Promising Adsorbents for Cationic and Anionic Dyes.

In this work, keratin sponges were prepared by freeze-drying method and tested for adsorption of Azure A and Methyl Orange dyes. The obtained materials showed a porosity of 99.92% and a mean pore size dimension of about 91 μm. The use of oxidized sucrose with a heating treatment at 150°C was demonstrated to be a useful crosslinking procedure alternative to the conventional glutaraldehyde. Keratin sponges showed a maximum adsorption capacity of 0.063 and of 0.037 mmol/g for Azure A and Methyl Orange, respectively. The absorption of the cationic dye Azure A onto keratin sponges was better described by Freundlich model while the isotherm adsorption of the anionic Methyl Orange was found to correlate with both Langmuir and Freundlich models. The mean free energies evaluated by using the D-R model indicated a physisorption of Methyl Orange and a chemisorptions of Azure A onto keratin sponges. Finally, the functionalization of keratin sponges with Zn Al hydrotalcites nanoparticles did not affect the adsorption performances of the adsorbent toward the cationic dye Azure A, while it improved those toward the anionic Methyl Orange, increasing the related removal efficiencies from 43 to 96%. Collectively, the reported data indicates that the combination of keratin with hydrotalcites nanoparticles is a good strategy to obtain more functional adsorbent materials of potential interest for water treatment and purification.

Characterization of dexamethasone loaded collagen-chitosan sponge and in vitro release study

The aim of the present work is the development of porous mucoadhesive bio-sponge as a vehicle for release of dexamethasone for the treatment of oral mucositis. The influence of mixing collagen with chitosan on crystallinity structure and thermal behavior of both polymers were investigated. The polymer blends and dexamethasone-loaded polymers were characterized by FT-IR, SEM scanning, and swelling ability. The release study of the drug from chitosan, collagen, and collagen-chitosan (1:1) sponges was carried out in vitro. X-Ray diffraction of the collagen-chitosan film showed a semi-crystalline structure, that has a great influence on drug release. DSC curve showed one endothermal peak for neat and hybrid polymer sponges, confirming there was no denaturation of collagen fiber, and there was no phase separation between polymers. FT-IR results showed the forming of electrostatic and H-bonding between collagen and chitosan and the forming of H-bonding between dexamethasone and studied polymers. SEM for sponges showed that adding collagen to chitosan increased pores size, dexamethasone was clearly shown immobilized on the surface of polymer films. Drug release from the hybrid sponge was faster than the chitosan sponge, which ended in 16 h, and was slower than the collagen sponge which ended in 5 h. The formulation based on collagen-chitosan (1:1) blend was able to control drug release within 10 h.

An Alginate Hybrid Sponge with High Thermal Stability: Its Flame Retardant Properties and Mechanism.

The worldwide applications of polyurethane (PU) and polystyrene (PS) sponge materials have been causing massive non-renewable resource consumption and huge loss of property and life due to its high flammability. Finding a biodegradable and regenerative sponge material with desirable thermal and flame retardant properties remains challenging to date. In this study, bio-based, renewable calcium alginate hybrid sponge materials (CAS) with high thermal stability and flame retardancy were fabricated through a simple, eco-friendly, in situ, chemical-foaming process at room temperature, followed by a facile and economical post-cross-linking method to obtain the organic-inorganic (CaCO3) hybrid materials. The microstructure of CAS showed desirable porous networks with a porosity rate of 70.3%, indicating that a great amount of raw materials can be saved to achieve remarkable cost control. The sponge materials reached a limiting oxygen index (LOI) of 39, which was greatly improved compared with common sponge. Moreover, with only 5% calcium carbonate content, the initial thermal degradation temperature of CAS was increased by 70 °C (from 150 to 220 °C), compared to that of calcium alginate, which met the requirements of high-temperature resistant and nonflammable materials. The thermal degradation mechanism of CAS was supposed based on the experimental data. The combined results suggest promising prospects for the application of CAS in a range of fields and the sponge materials provide an alternative for the commonly used PU and PS sponge materials.

Superswelling Hybrid Sponge from Water Glass for Selective Absorption of Crude Oil and Organic Solvents.

A lightweight super hydrophilic hybrid sponge is designed and demonstrated out of water glass and an organic polymer, which has a macroporous flaky nature and is superflexible with an apparent density of 0.069 g cc–1, ∼97% porosity, and 3000% water uptake. The octadecyltrimethoxy silane-modified hybrid sponge exhibits selective absorption of oil and organic solvents in open water. An absorption capacity in the range 12–23 g g–1 for the test liquids light crude oil, engine oil, paraffin oil, chloroform, kerosene, and hexane is revealed. Absorption capacity by a weight basis was directly proportional to the density and inversely proportional to the viscosity of test liquids. Trials under both stagnant and turbulent conditions verify selective uptake of oil from sea water. Complete regeneration of the absorbent was possible for ten cycles for the test liquids. The work provides design of an affordable water clean-up material alternative to commonly used polyurethane sponges.

Highly Conductive Multifunctional rGO/CNT Hybrid Sponge for Electromagnetic Wave Shielding and Strain Sensor

AbstractOne of the potential applications for carbon nanotube (CNT) sponge prepared through chemical vapor deposition (CVD) is as a strain sensor. However, the sensitivity of CNT sponge is strongly impeded by the point‐to‐point contact between individual CNTs. A novel method is proposed to introduce reduced graphene oxide (rGO) as a conducting bridge into CNT sponge, in order to dramatically improve the CNT contact. The graphene oxide (GO) is coated onto polystyrene (PS) spheres forming a suspension that is infiltrated into the CVD‐derived CNT sponge under vacuum. The PS spheres are decomposed and GO is reduced by postannealing. Scanning electron microscopy confirms the successful introduction of rGO. A small amount of rGO can effectively increase the electrical conductivity of the CNT sponge by ≈30% without an observable increase in density. A dramatic increment of 66% in sensitivity factor is achieved. Compared with CNT sponge, the microwave shielding effectiveness of the rGO/CNT hybrid sponge is 50% larger. This hybrid sponge is very promising for use as a high‐sensitivity strain sensor in different environments (both in the air and under water) and for high‐efficiency electromagnetic shielding protection.

Novel ZnO/N-halamine-Mediated Multifunctional Dressings as Quick Antibacterial Agent for Biomedical Applications.

Cutaneous hemorrhage often occurs in daily life which may cause infection and even amputation. This research aims to develop a novel chitosan dressing impregnated with ZnO/N-halamine hybrid nanoparticles for quick antibacterial performance, outstanding hemostatic potential, high porosity, and favorable swelling property through combining sonication and lyophilization processing. After 30 days of storage, about 90% bacterial cell viability loss could be observed toward both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli O157:H7 within 30 min of contact by colony counting method. The hybrids assembled much more platelet and red blood cell as compared with pure chitosan control. Moreover, the lower blooding clotting index value gave evidence that these composites could control hemorrhaging and reduce the probability of wound infection. No potential skin irritation and toxicity were detected using in vitro cytocompatibility and a skin stimulation test. Therefore, this work demonstrated a facile and cost-effective approach for the preparation of N-halamine-based hybrid sponges which show promising application for wound dressings.

Uranium Extraction: A Marine‐Inspired Hybrid Sponge for Highly Efficient Uranium Extraction from Seawater (Adv. Funct. Mater. 32/2019)

Uranium Extraction: A Marine‐Inspired Hybrid Sponge for Highly Efficient Uranium Extraction from Seawater (Adv. Funct. Mater. 32/2019)

Nitrogen-doped and Fe-filled CNTs/NiCo2O4 porous sponge with tunable microwave absorption performance

Lightweight, highly efficient, thermal stable microwave absorption materials are highly desirable but challenging for electromagnetic protection. Impedance matching and electromagnetic loss are two crucial factors for the microwave absorption materials design. Here, we successfully designed and synthesized a lightweight (31.5 mg/cm3) and porous NiCo2O4@carbon nanotubes (CNTs) hybrid sponge (NiCo2O4@CNTs) based on N-doped and Fe-filled CNTs. The as-prepared NiCo2O4@CNTs shows high thermal stability (>500 °C) and excellent microwave absorption properties with a minimum reflection loss value of - 45.1 dB at 9.0 GHz for absorber thickness of 2.5 mm. Moreover, the maximum absorption peak frequency and effective microwave absorption region (<10 dB) can be controlled in the range of 4.0–16.0 GHz by varying the thickness of the absorber. The highly efficient electromagnetic absorption performance of the sponge is mainly attributed to the high dipolar polarization, interfacial polarization loss and suitable impedance matching characteristic. These results indicate that the NiCo2O4@CNTs sponge can serve as the lightweight, highly efficient, and high temperature resistant microwave absorption materials.

Permanent superhydrophilic surface modification in microporous polydimethylsiloxane sponge for multi-functional applications

Polydimethylsiloxane (PDMS) is one of the most preferred material in microfluidic device/biomedical applications because of its unique properties. However, improvement in surface wettability of PDMS is highly desired for microfluidic and biomedical applications as its surface is inherently hydrophobic in nature that restricts flow of aqueous fluid or adherence of biomolecules onto its surface. In spite of several surface modification techniques, prompt recurrence of hydrophobic properties is quite typical in PDMS. Here, we demonstrate a facile and a permanent conversion of a hydrophobic PDMS sponge onto a superhydrophilic state. PDMS sponge was prepared using an eco-friendly sugar leaching method and modified by an ultra-thin coating of polyacrylic acid (PAA). The resultant PDMS-PAA hybrid sponge was found to have highly stable and sustained superhydrophilic property for more than 18 months with water absorption efficiency as high as 89%. Valuable applications like, portable pressure pump in a microfluidic device and as a bioactive matrix for microbial cell immobilization for biodegradation of distillery industry effluent treatment has been demonstrated using these surface modified PDMS sponges.

Hydrophobic, blocky silica-reduced graphene oxide hybrid sponges as highly efficient and recyclable sorbents

Silica aerogels are prone to be destroyed due to their brittleness and low mechanical properties, which limits their applications. To break the unfavorable situation, we presented a scalable and facile approach to assemble blocky silica-reduced graphene oxide (SiO2-rGO) hybrid sponges by atmospheric pressure drying technique. Briefly, ungelled silica solution from two-step sol-gel of tetraethoxysilane (TEOS), was incorporated into compressible graphene sponge (CGS). Different silicon concentration ratios had great influence on the performance of hybrid sponges. When VTEOS: Vethanol was fixed at 1:15, the sample had good flexibility and could absorb 8.5–10.2 times its own mass of solvents, but the adsorption efficiency slightly decreased with the increase of the number of experiments. When VTEOS: Vethanol was fixed at 4:7, the SiO2-rGO hybrid sponges exhibited unbroken shape, low volume shrinkage (24%), large specific surface area (803.351 m2/g), and high mass retention (83.64%) at 790 °C of thermal treatment. Moreover, they could support approximately 146 times their weight without structural damage, and possess excellent hydrophobicity with 129 ± 1° of water contact angle. These superior properties enable SiO2-rGO hybrid sponges to exhibit highly efficient absorption of oils and toxic solvents, to be regenerated (10 times) with the full release of adsorbates by heat treatment.

A Marine‐Inspired Hybrid Sponge for Highly Efficient Uranium Extraction from Seawater

AbstractMarine sponges are used as biomonitors of heavy metals contamination in coastal environment as they process large amounts of water and have a high capacity for accumulating heavy metals. Here, inspired by the unique physical and physiological features of marine sponges, a surface engineered synthetic sponge for the highly efficient harvesting of uranium from natural seawater is developed. An ultrathin poly(imide dioxime) (PIDO)/alginate (Alg) interpenetrating polymer network hydrogel layer is uniformly wrapped around the skeleton of a melamine sponge (MS) substrate through a simple dipping–drying–crosslinking process, providing the hybrid MS@PIDO/Alg sponge with excellent uranium adsorption performance and sufficient mechanical strength to withstand the harsh conditions of practical applications. The maximum adsorption capacity reaches 910.98 mg‐U g‐gel‐1 for the PIDO/Alg hydrogel layer and 291.51 mg‐U g‐sponge‐1 for the whole hybrid MS@PIDO/Alg sponge in uranium‐spiked natural seawater. The adsorption capacity measured after 56 d of exposure in 5 tons of natural seawater is evaluated to be 5.84 mg‐U g‐gel‐1 (1.87 mg‐U g‐sponge‐1). This novel approach shows great promise for the mass production of high‐performance sponge adsorbent for uranium recovery from natural seawater and nuclear waste.