Hollow Microcapsules Research Articles

Hyaluronic acid/chitosan microcapsules capped with hollow CuS nanoparticles for NIR/pH dual-responsive drug release

Hollow natural polysaccharide microcapsules have broad applications in drug delivery field due to their excellent biocompatibility and drug loading efficiency. In this paper, pH/near-infrared (NIR) dual-responsive microcapsules composed of hyaluronic acid (HA), chitosan (CS) and hollow CuS (HA/CS/HA@CuS) had been fabricated via a layer-by-layer (LbL) approach. The negative charge, rough surface and hollow structure of microcapsules are very favorable for loading positively charged DOX. As a result, hollow microcapsules display a high drug loading efficiency of 91.15 %. The variation in the degree of amino ionization at different pH values leads to the changes in the electrostatic force between CS/HA multilayers, resulting in the structural change in microcapsules. Therefore, microcapsules exhibit significant pH-responsive drug release properties. In addition, hollow CuS nanoparticles with excellent photothermal conversion ability are capped on the multilayer surface, enabling microcapsules to exhibit excellent NIR-responsive drug delivery properties. Overall, hyaluronic acid/chitosan-based hollow microcapsules with notable pH/NIR dual-responsiveness have been prepared, which can be used as a potential drug carrier for controlled drug delivery and photothermal chemical combination therapy.

Fabrication of natural mesoporous Diatom biosilica microcapsules with high oil-carrying capacity and tribological property

In this study, fluorosilane-modified hollow mesoporous Diatom biosilica oil-carrying microcapsules (Oil@HMSNs/DE-F) were successfully synthesized using diatomite as hard-template, and dimethylsiloxane oil and hollow mesoporous silica as the core materials. Such microcapsules exhibited high oil-carrying capacity (41 %) and oil-carrying stability, which significantly higher than the Oil@DE-F microcapsules (33 %) (Comparison). Tribological tests showed that the Oil@HMSNs/DE-F composite coatings have excellent tribological properties and mechanical properties. Amazingly, 6 wt% Oil@HMSNs/DE-F epoxy composites coatings reduced the coefficient of friction by 79.9 % and the wear rate by 98.1 % compared to pure epoxy.

Incorporation of CuS nanorods in polyelectrolyte multilayer microcapsules improved cancer cell cytotoxicity and signal intensity in ultrasound imaging

The fabrications of hollow microcapsules (MCs) with new architecture and ability to incorporate different nanomaterials have received great interest for targeted cancer therapy. Recently, CuS based nanomaterials have been demonstrated to possess the ability to mimic Fenton-like activity in tumor environment and inducing cancer cell apoptosis by generating highly reactive oxygen species (ROS). In this study, we have developed poly(allylamine) hydrochloride (PAH)/dextran sulfate (DS) polyelectrolyte MCs capable of carrying doxorubicin (DOX) for targeted cancer therapy and ultrasound imaging. The electron microscopy investigations showed the formation of polymeric MCs of 3 µm in size with incorporated CuS NRs in their interior structure. The surface modification of MCs with folic acid (FA), and encapsulation of model hydrophilic molecules in MCs was studied by UV–Visible (UV–Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and confocal laser scanning microscopy. The encapsulation efficiency of DOX was found to be 56 % and the release was found to be linear at pH 5.5 and 7.4 in the absence of ultrasound exposure. The ultrasound exposure resulted in sudden rupture of MCs at 1 MHz and 1 W/cm2 and caused burst release of DOX at both pH conditions. The FA decorated PAH/DS/CuS NR MCs exhibited improved anti-cancer activity against MDA-MB-231 cancer cells due to the synergistic effects of ultrasound mediated burst release of chemotherapeutic drug (DOX), glutathione-stimulated ROS and targeted cancer therapy. Further, the capsules showed better echogenicity than that of control PAH/DS MCs when imaged under medical ultrasound-scanning system. Hence, the MCs demonstrated in this study have huge potential for targeted cancer theranostics by offering an option to image the cancer cells during the treatment period.

Benzoyl peroxide encapsulation in poly(urea‐formaldehyde) microcapsules for use in dental materials

AbstractNew self‐healing resin composites with tertiary amine microcapsules enhance the mechanical performance of dental restorations. However, a higher concentration of dibenzoyl peroxide (BPO) must be added to the composite to react with the core material when the microcapsules rupture, reducing the shelf life of dental materials due to their reactivity. As a result, one approach to reducing the amount of BPO dissolved in dental resin is to microencapsulate it. Thus, this manuscript described the encapsulation of BPO in poly(urea‐formaldehyde) (PUF) microcapsules (MC) and investigated its effect on the flexural strength of BisGMA/TEGDMA composites. To synthesize hollow MC, poly(acrylic acid) (PAA) was tested as a continuous phase viscosity modifier. The MC were then infiltrated with BPO dissolved in linseed oil as core materials. PAA in continuous phase increased MC diameter due to improved air bubble stability. BPO dissolved in linseed oil was successfully infiltrated into empty PUF MC, causing the MC shell wall to expand. The dental resin had adequate adhesion to the PUF shell, which ruptured under induced stress. Thus, the MC filled with BPO as a healing agent has the potential to reduce the amount of BPO that is typically dissolved in the monomeric phase of dental materials, which can increase the shelf life of self‐healing dental materials.Highlights The reactivity of dibenzoyl peroxide (BPO) affects resin stability in dental materials. When combined with tertiary amines, BPO acts as a healing agent in self‐healing composite materials. BPO dissolved in linseed oil can be infiltrated in PUF microcapsules and increase its size. Hollow microcapsules synthesized in a more viscous continuous phase have a larger diameter. Microencapsulated BPO is released during stress stimuli in dental resin.

Functionalized Calcium Carbonate-Based Microparticles as a Versatile Tool for Targeted Drug Delivery and Cancer Treatment.

Nano- and microparticles are increasingly widely used in biomedical research and applications, particularly as specific labels and targeted delivery vehicles. Silica has long been considered the best material for such vehicles, but it has some disadvantages limiting its potential, such as the proneness of silica-based carriers to spontaneous drug release. Calcium carbonate (CaCO3) is an emerging alternative, being an easily available, cost-effective, and biocompatible material with high porosity and surface reactivity, which makes it an attractive choice for targeted drug delivery. CaCO3 particles are used in this field in the form of either bare CaCO3 microbeads or core/shell microparticles representing polymer-coated CaCO3 cores. In addition, they serve as removable templates for obtaining hollow polymer microcapsules. Each of these types of particles has its specific advantages in terms of biomedical applications. CaCO3 microbeads are primarily used due to their capacity for carrying pharmaceutics, whereas core/shell systems ensure better protection of the drug-loaded core from the environment. Hollow polymer capsules are particularly attractive because they can encapsulate large amounts of pharmaceutical agents and can be so designed as to release their contents in the target site in response to specific stimuli. This review focuses first on the chemistry of the CaCO3 cores, core/shell microbeads, and polymer microcapsules. Then, systems using these structures for the delivery of therapeutic agents, including drugs, proteins, and DNA, are outlined. The results of the systematic analysis of available data are presented. They show that the encapsulation of various therapeutic agents in CaCO3-based microbeads or polymer microcapsules is a promising technique of drug delivery, especially in cancer therapy, enhancing drug bioavailability and specific targeting of cancer cells while reducing side effects. To date, research in CaCO3-based microparticles and polymer microcapsules assembled on CaCO3 templates has mainly dealt with their properties in vitro, whereas their in vivo behavior still remains poorly studied. However, the enormous potential of these highly biocompatible carriers for in vivo applications is undoubted. This last issue is addressed in depth in the Conclusions and Outlook sections of the review.

Photochemical formation of hollow silicone microcapsule arrays on periodic microswelling structures of silicone rubber using 193 nm ArF excimer laser for microencapsulation of electrolytes

Microencapsulation for developing energy storage devices has been widely reported recently. In heat storage, many studies have been conducted to microencapsulate phase change materials with various shell materials. In contrast, there are still few studies on microencapsulation in power storage. In this paper, we found a new method to form hollow silicone microcapsule arrays for microencapsulation of electrolytes and suggested a new micropower storage application. Single layer of silica microspheres was formed on silicone rubber, then an ArF excimer laser irradiated the surface. Main chains of Si–O–Si bonds of silicone rubber underneath the microspheres could be photodissociated to lower the molecular weight, resulting in the formation of periodic microswelling structure of silicone rubber. Concurrently, a spherical microcapsule was also photochemically formed on each the microswelling structure. We systematically investigated the optimal conditions for chemical pre-etching to tune the gaps between microspheres to form spherical microcapsules and for chemical post-etching to completely remove the enclosed microspheres to form hollow microcapsules. The microcapsules formed consisted of silicone and were porous. Moreover, micro/nanoholes on the side/top of each microcapsule to encapsulate various electrolytes were successfully formed. The present results are expected to be applied as a micropower storage device that functions underwater.

Driving inward growth of lithium metal in hollow microcapsule hosts by heteroatom‐controlled nucleation

AbstractThe application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits. Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity; however, uncontrollable and nonuniform deposition of Li remains a challenge. In this study, we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host. Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag+ and metallic Zn. Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating. Through combined electrochemical, microstructural, and computational studies, we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and, in turn, enhancing electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li metal batteries.

A combined engineering of hollow and core-shell structures for C@MoS2 microcapsules toward high-efficiency electromagnetic absorption

Rational design of profitable structure is widely considered as an effective strategy for electromagnetic wave absorbing materials (EWAMs) to improve their performance. Herein, we conduct a combined engineering of hollow and core-shell structures, in which surface shell is formed by a number of MoS2 nanosheets crossing each other and internal core is hollow carbon microcapsule (HC). HC has strong dielectric loss ability, and its hollow structure facilitates the multiple reflection of incident EM wave. The construction of MoS2 shells not only improves impedance matching but also introduces heterogeneous interfaces that result in interfacial polarization loss. It is found that the synergistic effect of intrinsic loss mechanisms and structural advantages endow C@MoS2 composites (HCM-x) with excellent EM wave absorption performance, and especially for HCM-2, whose minimum reflection loss (RL) intensity and effective absorption bandwidth (EAB) are −63.8 dB and 6.0 GHz, respectively. It is believed that this work is valuable for the enhancement of performance for EWAMs through the upgrade of microstructure and regulation of chemical composition.

The effects of stiffness on the specificity and avidity of antibody-coated microcapsules with target cells are strongly shape dependent

Antibody modification is a common method for endowing drug carriers with the ability to target specific cells. Recent studies suggest that the efficacy of these antibody-modified drug carriers is closely related to their physicochemical properties, such as size, shape, stiffness, charge, and surface chemistry. In this study, we functionalized microcapsules with antibodies to investigate the combined effect of shape and stiffness on their targeting ability. We synthesized hollow microcapsules, both spherical and rod-shaped, with adjustable stiffness using calcium carbonate particles as templates and silk fibroin (SF) as the shell material. These microcapsules were then functionalized with trastuzumab (TTZ) to enhance targeting capabilities. Our analysis revealed that increasing stiffness significantly improved the specificity and avidity of TTZ-coated rod-shaped microcapsules, but not spherical ones, indicating a strong shape-dependent influence of stiffness on these properties. Additionally, we explored the mechanisms of endocytosis using various inhibitors and found that both macropinocytosis and clathrin played critical roles in the cellular uptake of microcapsules. Furthermore, we loaded microcapsules with doxorubicin (DOX) to evaluate their anti-tumor efficacy. The stiffest TTZ-coated, DOX-loaded rod-shaped microcapsules demonstrated the most potent anti-tumor effects on BT-474 cells and the highest uptake in BT-474 3D spheroids. This research contributes to the development of more effective microcapsule-based target delivery systems and the realization of the full potential of microcapsule drug delivery systems.

N/P co-doped MXene hollow microcapsules by surfactants assisted hydrothermal-freeze drying for adjustable permeability

The assembly of MXene materials into microcapsules has drawn great attentions due to their unique properties. However, rational design and synthesis of MXene-based microcapsules with specific nanostructures at the molecular scale remains challenging. Herein, we report a strategy to synthesize N/P co-doped MXene hollow flower-like microcapsules with adjustable permeability via dual surfactants assisted hydrothermal-freeze drying method. In contrast to anionic surfactants, cationic surfactants exhibited effective electrostatic interactions with MXene nanosheets during the hydrothermal process. Manipulation of dual surfactants in hydrothermal process realized N and P co-doping of MXene to improve flexibility and promoted the generation of abundant internal cavities in flower-like microcapsules. Based on the unique microstructure, the prepared hollow flower-like microcapsules showed excellent performance, stability and reusability in size-selective release of small organic molecules. Moreover, the release rate can be controlled by turning the oxidation state and type of MXene. The strategy delineates promising prospects for the design of MXene-based microcapsules with specific structures.

A novel magnetically guided, oxygen propelled CoPt/Au nanosheet motor in conjugation with a multilayer hollow microcapsule for effective drug delivery and light triggered drug release.

In recent years, nanomotors have been developed and attracted extensive attention in biomedical applications. In this work, a magnetically-guided oxygen-propelled CoPt/gold nanosheet motor (NSM) was prepared and used as an active self-propelled platform that can load, transfer and control the release of drug carrier to cancer cells. As a drug carrier, the microcapsules were constructed by the layer-by-layer (LbL) coating of chitosan and carboxymethyl cellulose layers, followed by incorporation of gold and magnetite nanoparticles. Doxorubicin (DOX) as an anti-cancer drug was loaded onto the synthesized microcapsules with a loading efficiency of 77%. The prepared NSMs can deliver the DOX loaded magnetic multilayer microcapsule to the target cancer cell based on the catalytic decomposition of H2O2 solution (1% v/v) via guidance from an external magnetic force. The velocity of NSM was determined to be 25.1 μm s-1 in 1% H2O2. Under near-infrared irradiation, and due to the photothermal effect of the gold nanoparticles, the proposed system was found to rapidly release more drugs compared to that of an internal stimulus diffusion process. Moreover, the investigation of cytotoxicity of NSMs and multilayer microcapsules clearly revealed that they have negligible side effects over all the concentrations tested.

Co-encapsulation and release of apigenin and ascorbic acid in polyelectrolyte multilayer capsules for targeted polycystic ovary syndrome

Polycystic ovary syndrome (PCOS), a prevalent endocrine disorder in women of reproductive age, is linked to hormonal imbalances and oxidative stress. Our study investigates the regenerative potential of apigenin (AP, hydrophobic) and ascorbic acid (AC, hydrophilic) encapsulated within poly (allylamine hydrochloride) and dextran sulfate (PAH/DS) hollow microcapsules for PCOS. These microcapsules, constructed using a layer-by-layer (LbL) assembly, are found to be 4 ± 0.5 μm in size. Our research successfully demonstrates the co-encapsulation of AP and AC in a single PAH/DS system with high encapsulation efficiency followed by successful release at physiological conditions by CLSM investigations. In vitro tests with testosterone-treated CHO cells reveal that the dual-drug-loaded PAH/DS capsules effectively reduce intracellular ROS levels and apoptosis and offering protection. In an in-vivo zebrafish model, these capsules demonstrate active biodistribution to targeted ovaries and reduce testosterone levels through radical scavenging. Histopathological examinations show that the injected dual-drug-loaded PAH/DS microcapsules assist in the development of ovarian follicles in testosterone-treated zebrafish. Hence, this dual-drug-loaded system, capable of co-encapsulating two natural compounds, effectively interacts with ovarian cells, reducing cellular damage and normalizing PCOS conditions.

Aerogel-Like Material Based on PEGylated Hyperbranched Polymethylethoxysiloxane.

Aerogels are a class of materials that have gained increasing attention over the past several decades due to their exceptional physical and chemical properties. These materials are highly porous, with a low density and high surface area, allowing for applications such as insulation, catalysis, and energy storage. However, traditional aerogels, such as pure silica aerogels, suffer from brittleness and fragility, which limit their usefulness in many applications. Herein, we have addressed this problem by using organosilicon compounds, namely polymethylsilsesquioxane derivatives, for the synthesis of aerogel-like materials. Specifically, we have developed a novel approach involving surfactant-free synthesis of microcapsules from partially PEGylated hyperbranched polymethylethoxysiloxane. Due to the highly diphilic nature of these compounds, they readily concentrate at the oil/water interface in aqueous emulsions encapsulating oil droplets. During the subsequent condensation, the organosilicon precursor is consumed for hexane encapsulation (yielding hollow microcapsules) followed by the formation of a continuous condensed phase. Concurrently, methyl groups ensure the hydrophobicity of the resulting materials, which eliminates the need of using additional reagents for their hydrophobization.

Construction of hierarchical SiO2 microcapsule towards flame retardation, low toxicity and mechanical enhancement of epoxy resins

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers.

Polyphenol modification of graphene-stabilized emulsions to form electrically conductive polymer spheres

HypothesisPolyphenols, specifically tannic acid, should increase the hydrophilicity of graphene when added during the interfacial exfoliation through π-π stacking. Following Bancroft’s rule, increasing the hydrophilicity of graphene will result in a phase inversion of water-in-oil emulsions stabilized by graphene. Polymerization of the oil phase will then lead to graphene-coated spheres rather than graphene-stabilized polyHIPEs. ExperimentsOptical particle sizing, microscopy, contact angle, and electrical conductivity measurements were performed to determine the mechanism of sphere formation in graphene-stabilized emulsions modified with tannic acid. Studies focused on the effect of graphite flake size, graphite concentration, tannic acid concentration, and oil phase composition. Particle sizing and scanning electron microscopy examined the spheres' size, shape, and surface morphology. Contact angle measurements gave insight into the change in graphene surface energy. Conductivity studies examined the graphene shell surrounding the spheres. FindingsAdding tannic acid to graphene-stabilized emulsions induced a phase change from water-in-oil to oil-in-water. Contact angle measurements confirmed greater hydrophilicity of graphene in the presence of tannic acid. However, very high tannic acid concentrations led to a decrease in the stability of the emulsion. Varying the graphite flake size and concentration resulted in morphology and conductivity changes. Dilution of the monomer phase produced hollow microcapsules.

Assembly of Metal-Phenolic Networks onto Microbubbles for One-Step Generation of Functional Microcapsules.

The one-step assembly of metal-phenolic networks (MPNs) onto particle templates can enable the facile, rapid, and robust construction of hollow microcapsules. However, the required template removal step may affect the refilling of functional species in the hollow interior space or the in situ encapsulation of guest molecules during the formation of the shells. Herein, a simple strategy for the one-step generation of functional MPNs microcapsules is proposed. This method uses bovine serum albumin microbubbles (BSA MBs) as soft templates and carriers, enabling the efficient pre-encapsulation of guest species by leveraging the coordination assembly of tannic acid (TA) and FeIII ions. The addition of TA and FeIII induces a change in the protein conformation of BSA MBs and produces semipermeable capsule shells, which allow gas to escape from the MBs without template removal. The MBs-templated strategy can produce highly biocompatible capsules with controllable structure and size, and it is applicable to produce other MPNs systems like BSA-TA-CuII and BSA-TA-NiII . Finally, those MBs-templated MPNs capsules can be further functionalized or modified for the loading of magnetic nanoparticles and the pre-encapsulation of model molecules through covalence or physical adsorption, exhibiting great promise in biomedical applications.

Electrospun Polymeric Fibers Decorated with Silk Microcapsules via Encapsulation and Surface Immobilization for Drug Delivery.

Hollow polymer microcapsules as drug carriers have the advantages of drug protection, storage, and controlled release. Microcapsules combined with tissue engineering scaffolds such as electrospun microfibers can enhance long-term local drug retention. However, the combination methods of microcapsules and fibers still need to be further explored. Here, we developed different technical approaches to functionalize electrospun polycaprolactone (PCL) microfibers with silk fibroin (SF) microcapsules through encapsulation and surface immobilization, including direct blending and emulsion electrospinning for encapsulation, as well as covalent and cleavable disulfide-linkage for surface immobilization. The results of "blending" approach showed that silk microcapsules with different sizes could be uniformly encapsulated inside electrospun fibers without aggregation. To further reduce the use of organic solvents, the microcapsules in the aqueous phase can be uniformly distributed in the PCL organic phase and successfully electrospun into fibers using surfactant span-80. For surface immobilization, silk microcapsules were efficiently covalent binding to the surface of electrospun PCL fibers via click chemistry and exhibited noncytotoxic. Based on this method, with the incorporation of a disulfide bond, the linkages between microcapsule and fiber could be cleaved under reducing conditions. These microcapsule-electrospun fiber combination methods provide sufficient options for different drug delivery requirements. This article is protected by copyright. All rights reserved.

Hierarchically hollow microcapsules with antibacterial and angiogenic properties for abdominal wall defects treatment

The utilization of mesh materials to repair abdominal wall defects (AWDs) is one of the most common operations in the surgical field. However, the repair efficiency for biological meshes is restricted by poor neovascularization and limited abilities to prevent bacterial contamination. To address these issues, we design a new type of hierarchically hollow microcapsules (HHMs) by microfluidics. The hollow mesoporous silica nanoparticles filled in the aqueous core of HHMs form the first hollow structure, while the polymer shell of HHMs with tailorable thickness forms the second hollow structure. Under the precise emulsification process of microfluidics, HHMs have a high monodispersity with the coefficient of variation value about 1.9%. Taking advantages of the hierarchically hollow structure, the resultant microcapsules can store large amounts of angiogenic molecules, and deliver these cargos in a controlled manner. In vitro experiments find that the bioactivities of angiogenic molecules are well preserved after microencapsulation and promote the capillary tube formation of endothelial cells. In addition, silver nanoparticles (AgNPs) are incorporated into the HHMs shell to provide antibacterial properties for these microcapsules. When AgNPs concentration set to 0.4‰, the colony counting is reduced by 99.8% for Gram-negative bacteria and 94.8% for Gram-positive bacteria, while the proliferation activity of normal cells remains more than 80.0%. In vivo experiments find that HHMs can facilitate the new blood vessel formation, restrain the bacteria adhesion, and decrease the inflammatory response after implantation into a rat model with AWDs. These unique characteristics of HHMs thus create a healthy environment for biological meshes to induce the regeneration of AWDs, accompanied by collagen deposition and granulation formation. Collectively, the proposed HHMs are promising devices in the application of defected tissue repair.

Hollow polyphosphazene microcapsule with rigid-flexible coupling cationic skeletons for highly efficient and selective adsorption of anionic dyes from water

An amino-rich hollow polyphosphazene microcapsule with rigid-flexible coupling cationic skeleton (HTCM) was facilely prepared by one-step polycondensation from hexachlorocyclotriphosphazene and tetraethylenepentamine. The systematic adsorption studies for six single dye systems and three binary mixed dye systems showed that HTCM possessed a highly-efficient and selective adsorption behavior towards anionic dyes from water. Especially, the adsorption capacity of HTCM towards methyl orange (MO) at equilibrium reached 1009.66 mg g−1 at 25 °C, and the relative separation factors of anionic dye MO for three cationic dyes (methylene blue, Crystal violet and Rhodamine B) was up to 124.22, 124.87 and 136.35, respectively. The adsorption rate of MO onto HTCM was very rapid, attaining 68.6 % of adsorption equilibrium capacity for MO within the first 30 min. The adsorption kinetics, isotherm and thermodynamic analysis revealed that the uptake behavior of HTCM towards MO obeyed pseudo-second-order kinetic model, intraparticle diffusion model and Langmuir model, and the uptake process was spontaneous and endothermic. As verified from FT-IR and XPS analysis for HTCM before and after MO adsorption, the adsorption mechanism of HTCM for MO involved electrostatic interaction and hydrogen bonding. The present study promises the potential of HTCM for highly selective separation of anionic dyes from wastewater.

Study of self-healing ability of thermosetting polymer composites, containing hollow glass fibers and microcapsules using ultrasonic non-destructive testing

Study of self-healing ability of thermosetting polymer composites, containing hollow glass fibers and microcapsules using ultrasonic non-destructive testing