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Due to the increasing demand for artificial joint implants, two types of clays, montmorillonite (MMT) and halloysite nanotube (HNT), have been used either in combination as hybrid additives to reinforce the properties of the widely used polymer in the biomedical field (ultra‐high molecular weight polyethylene (UHMWPE)). The 5% nanoclay content was incorporated into all manufactured nanocomposite materials. Several tests were conducted to evaluate the mechanical performance of these nanocomposite materials, including Izod, hardness, abrasion, and compression. Additionally, XRD analysis, scanning electron microscopy, and biocompatibility study were investigated to examine these nanocomposite's capacity to suit orthopedic applications. Compared to pure UHMWPE, the "hybridization" effect successfully increased the resistance of the nanocomposite. Although 5% HNT‐UHMWPE composites underwent some degradation in impact strength, the excellent ductility preserved the composites to fail without catastrophic fracture. Based on the MTT assay, all nanocomposites exhibited good biocompatibility, evident by favorable cell growth with no signs of cytotoxicity after up to 96 h of incubation in media with different amounts of material in solution. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of halloysite nanotube (HNT) content on mechanical and shape memory properties of additively manufactured polyurethane (PU)/HNT nanocomposites. The inclusion of 8 wt% HNTs increases their tensile strength by 30.4% when compared with that of virgin PU at 44.75 MPa. Furthermore, consistently significant increases in tensile modulus, compressive strength and modulus, as well as specific energy absorption are also manifested by 47.2%, 34.0%, 125% and 72.7% relative to neat PU at 2.29 GPa, 3.88 MPa, 0.28 GPa and 0.44 kJ/kg respectively. However, increasing HNT content reduces lateral strain due to the restricted mobility of polymeric chains, leading to a decrease in negative Poisson's ratio (NPR). As such, shape recovery ratio and time of PU/HNT nanocomposites are reduced by 9 and 45% with the inclusion of 10 wt% HNTs despite an increasing shape fixity ratio up to 12% relative to those of neat PU. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of halloysite nanotube (HNT) content on mechanical and shape memory properties of additively manufactured polyurethane (PU)/HNT nanocomposites. The inclusion of 8 wt% HNTs increases their tensile strength by 30.4% when compared with that of virgin PU at 44.75 MPa. Furthermore, consistently significant increases in tensile modulus, compressive strength and modulus, as well as specific energy absorption are also manifested by 47.2%, 34.0%, 125% and 72.7% relative to neat PU at 2.29 GPa, 3.88 MPa, 0.28 GPa and 0.44 kJ/kg respectively. However, increasing HNT content reduces lateral strain due to the restricted mobility of polymeric chains, leading to a decrease in negative Poisson’s ratio (NPR). As such, shape recovery ratio and time of PU/HNT nanocomposites are reduced by 9 and 45% with the inclusion of 10 wt% HNTs despite an increasing shape fixity ratio up to 12% relative to those of neat PU.

Our environment is getting effluent day by day due to modernization and industrialization which leads to more serious issues in recent years. Hydrogen energy is considered a green, clean, and sustainable alternative energy carrier. So, the present work is focused on the effective storing of hydrogen on metal hydride (MgH2) and natural clay nanotube (A-HNT) decorated conductive polymer (PANI) nanocomposite. A facile two-step synthesis was adopted for the preparation of B-MgH2/A-HNT/PANI nanocomposite. The structural, morphological, elemental, and specific surface area studies of the prepared B-MgH2/A-HNT/PANI nanocomposite confirm the presence of B-MgH2, A-HNT, and PANI. During ball milling, more defective sites were created at the surface of MgH2, A-HNT, and PANI and thereby more specific surface area (441.2 m2 g−1) in the case of B-MgH2/A-HNT/PANI nanocomposite. In contrast, the addition of PANI and A-HNT promotes quick disintegration of B-MgH2 at 252 °C instead of 352 °C which is authenticated by all-thermal analysis (Thermo Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Temperature-Programmed Desorption (TPD)). The amount of stored hydrogen (Sievert's-like hydrogenation setup) was found to be 7.9 wt% at 110 °C, and the binding energy of stored hydrogen lies in the recommended range (0.33–0.6 eV) of US-Department of Energy (US-DOE) 2025 targets. The prepared B-MgH2/A-HNT/PANI nanocomposite was utilized as a working electrode in the electrochemical hydrogen storage where 2498 mAh/g discharge capacity (corresponds to 7.5 wt% hydrogen storage capacity) was attained at 24th cycle of the discharging process. In addition, coulombic efficiency of 95.3%, capacitance retention of 79.8%, and superior corrosion resistance of 25.5 mA/cm2 were noticed for B-MgH2/A-HNT/PANI. The improved electrochemical activity of B-MgH2/A-HNT/PANI was attributed to the synergistic effect of A-HNT and PANI species in B-MgH2 towards charge transfer during the charging and discharging processes. Moreover, the hydrogen storage capacity of B-MgH2/A-HNT/PANI estimated using Sievert's-like hydrogen storage method is almost the same as in the electrochemical storage method. Hence, these characteristics authenticate that the prepared B-MgH2/A-HNT/PANI nanocomposite may serve as an excellent hydrogen storage medium for weakly chemisorbed hydrogens and as a working electrode to store hydrogens electrochemically for renewable energy storage applications. [ABSTRACT FROM AUTHOR]

The response of clay minerals to changes in pore fluid salinity, particularly in coastal areas such as bays, lagoons, sounds, sloughs, and estuaries, has not been extensively studied. Herein, the influence of salinity exchange on the microscopic interaction and sedimentation behavior of halloysite nanotubes in an aqueous condition was investigated. In-situ microscopic observations and macro-scale sedimentation experiments reveal that halloysite nanotubes tend to disperse in pore fluids with high ionic strength because salt ions weaken the edge-to-face halloysite fabrics. Salinity exchange experiments demonstrate the permanent alteration of flocculation and sedimentation behavior due to the residual salt ions on the HNT surfaces. Even when the salt concentration is restored to its initial value, the presence of residual salts leads to the formation of a large and open floc structure, resulting in slower settling and a loosely packed final sediment. Our study provides a thorough understanding of the salt effect on sediment formation, including changes in the microscopic clay particle fabrics during salinity exchange. [Display omitted] • Halloysite nanotube behavior under varying salinity is studied using in-situ liquid-phase microscopy and sedimentation tests. • At low salinity, halloysite nanotubes (HNTs) form large aggregates due to Coulombic and van der Waals attractions. • Increasing salinity compresses the double-layer of HNTs, effectively reducing particle interactions and aggregate sizes. • In-situ liquid-phase microscopy provided a comprehensive view of the entire process, form initial flocculation to final sediments of clay. [ABSTRACT FROM AUTHOR]

Generally, the injection method is recommended as the best efficient method for vaccine applications in fish. However, labor-intensive and difficult injection for certain fish sizes is always considered as a limitation to aquatic animals. To demonstrate the effectiveness of a novel oral delivery system for the piscine vaccine with nano-delivery made from nano clay, halloysite nanotubes (HNTs) and their modified forms were loaded with killed vaccines, and we determined the ability of the system in releasing vaccines in a mimic digestive system. The efficaciousness of the oral piscine vaccine nano-delivery system was evaluated for its level of antibody production and for the level of disease prevention in tilapia. Herein, unmodified HNTs (H) and modified HNTs [HNT-Chitosan (HC), HNT-APTES (HA) and HNT-APTES-Chitosan (HAC)] successfully harbored streptococcal bivalent vaccine with inactivated S. agalactiae, designated as HF, HAF, HCF and HACF. The releasing of the loading antigens in the mimic digestive tract demonstrated a diverse pattern of protein releasing depending on the types of HNTs. Remarkably, HCF could properly release loading antigens with relevance to the increasing pH buffer. The oral vaccines revealed the greatest elevation of specific antibodies to S. agalactiae serotype Ia in HCF orally administered fish and to some extent in serotype III. The efficacy of streptococcal disease protection was determined by continually feeding with HF-, HAF-, HCF- and HACF-coated feed pellets for 7 days in the 1st and 3rd week. HCF showed significant RPS (75.00 ± 10.83%) among the other tested groups. Interestingly, the HCF-treated group exhibited noticeable efficacy similar to the bivalent-vaccine-injected group (RPS 81.25 ± 0.00%). This novel nano-delivery system for the fish vaccine was successfully developed and exhibited appropriated immune stimulation and promised disease prevention through oral administration. This delivery system can greatly support animals' immune stimulation, which conquers the limitation in vaccine applications in aquaculture systems. Moreover, this delivery system can be applied to carrying diverse types of biologics, including DNA, RNA and subunit protein vaccines. [ABSTRACT FROM AUTHOR]

To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite's modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs' size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model. [ABSTRACT FROM AUTHOR]

Halloysite nanotubes (HNT) have received widespread interest due to their unique microstructure and properties. They have been widely used as nano-containers or supporting materials to prepare advanced functional materials in many fields, spanning from life science and medical uses to energy and environmental applications. It is well-known that the performance of HNT is highly influenced by their surface area and pore volume, depending on the detailed structure properties, such as lumen space, wall thickness and length of HNT. Particularly, the loading ability of HNT is related to the detailed microstructures, such as morphology parameters (the inner/outer diameter and length), wall structure, active sites, interlayer space, as well as surface modification by organic groups and inorganic nanoparticles. As a special one-dimension nanoporous clay mineral with tubular morphology, the fundamental knowledge on the microstructure of HNT is of key importance to their specific applications. This review summarized several key factors related to the microstructures of halloysite, such as the morphology and origin of HNT, the coexisting impurities and the dispersion degrees of HNT, then rationalize the relations between the microstructures and physicochemical properties of halloysite, followed by the recent progress on microstructures evolution of HNT under various modification methods such as calcination, acid/alkali treatment, pseudomorphic transformations, and surface modifications as well as functional loading, physical expansion and intercalation. [Display omitted] • Several key factors related to the microstructures of halloysite are summarized. • The relations between microstructures and physicochemical properties of HNTs. • Recent progress on microstructures and properties of HNTs under various modification methods. [ABSTRACT FROM AUTHOR]

The high concentrations of heavy metal ions in industrial effluents are one of the most challenging wastewaters to deal with. In this study and in order to change the inner diameter of the halloysite nanotubes (HNT), their internal surface was coated by different polymers (polydopamine, polyaniline and polystyrene) and then, the modified nanotubes were incorporated in the polyamide thin film NF membrane for the treatment of metal ions solutions. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) studies indicated that the internal coating was successful. Furthermore, the neat and modified nanofiltration (NF) membranes were characterized in terms of morphology, contact angle, water flux and metal ion rejection. The modified membranes displayed lower contact angle values (29.4% reduction) that can be linked to the hydrophilic groups in the structure of the coated polymers and the smoother surface of the thin film nanocomposite (TFN) membrane. In addition, the permeation fluxes of the modified membranes were improved significantly (33.4% improvement) without any major reduction in their ion rejection; that shows HNTs act as the channels to transfer water through the membrane structure while the coating of the inner surface of HNT reduces the size of the channel and makes more repulsion and steric hindrance for the ion to pass through the nanotubes. Among the fabricated membranes, the NF membrane with 0.05 wt% polystyrene-coated HNT showed the lowest contact angle (55.30o) and the highest water permeation flux (27.51 L m-2 hr-1), compared to the neat TFC membrane (15.26 L m-2 hr-1) and the NF membrane with 0.05 wt% unmodified HNT (20.62 L m-2 hr-1). [Display omitted] • The internal surface of HNTs was coated with different polymers through a novel polymerization method. • Polydopamine, polyaniline and polystyrene were used as the polymer for coating. • The modified HNTs were used to improve the performance of TFN NF membrane. • HNTs act as the channels to transfer water through the membrane structure. • The permeations of the TFN membranes with modified HNTs were improved significantly without any reduction in the rejection. [ABSTRACT FROM AUTHOR]

Innovative, composite mixed matrix membrane (MMM) structures with specific naturally occurring halloysite nanotubes (HNTs) provide new possibilities in gaseous and liquid mixtures separation. Halloysite filler, introduced into the polymer phase, can find itself useful both as natural clay mineral with adsorption/catalytic properties, as well as the convenient support for other, targeted and highly specialised nanoparticles. Numerous laboratory studies indicate that hydrophilicity of the resulting membrane is advantageously improved, providing higher pure water flux than obtained in the one-phase membrane. Optimised structures of the halloysite-based nano-fillers can find them useful in various technological applications, for example, separation of dyes or/and oils from post-processed wastewaters, the concentration of salts in solutions, inhibition of bacterial population growth, as well as separation of gaseous mixtures components. The research done so far and reported in the literature in respect to MMMs with halloysite, applied as a natural mineral and with targeted functionalisations, was systematized and presented. Particular attention was paid to the natural, unique halloysite nanoplates (HNPs), which potential use in technological applications is still not fully discovered and exploited. [ABSTRACT FROM AUTHOR]

To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite’s modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs’ size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model.

Generally, the injection method is recommended as the best efficient method for vaccine applications in fish. However, labor-intensive and difficult injection for certain fish sizes is always considered as a limitation to aquatic animals. To demonstrate the effectiveness of a novel oral delivery system for the piscine vaccine with nano-delivery made from nano clay, halloysite nanotubes (HNTs) and their modified forms were loaded with killed vaccines, and we determined the ability of the system in releasing vaccines in a mimic digestive system. The efficaciousness of the oral piscine vaccine nano-delivery system was evaluated for its level of antibody production and for the level of disease prevention in tilapia. Herein, unmodified HNTs (H) and modified HNTs [HNT-Chitosan (HC), HNT-APTES (HA) and HNT-APTES-Chitosan (HAC)] successfully harbored streptococcal bivalent vaccine with inactivated S. agalactiae, designated as HF, HAF, HCF and HACF. The releasing of the loading antigens in the mimic digestive tract demonstrated a diverse pattern of protein releasing depending on the types of HNTs. Remarkably, HCF could properly release loading antigens with relevance to the increasing pH buffer. The oral vaccines revealed the greatest elevation of specific antibodies to S. agalactiae serotype Ia in HCF orally administered fish and to some extent in serotype III. The efficacy of streptococcal disease protection was determined by continually feeding with HF-, HAF-, HCF- and HACF-coated feed pellets for 7 days in the 1st and 3rd week. HCF showed significant RPS (75.00 ± 10.83%) among the other tested groups. Interestingly, the HCF-treated group exhibited noticeable efficacy similar to the bivalent-vaccine-injected group (RPS 81.25 ± 0.00%). This novel nano-delivery system for the fish vaccine was successfully developed and exhibited appropriated immune stimulation and promised disease prevention through oral administration. This delivery system can greatly support animals’ immune stimulation, which conquers the limitation in vaccine applications in aquaculture systems. Moreover, this delivery system can be applied to carrying diverse types of biologics, including DNA, RNA and subunit protein vaccines.

Halloysite nanotubes (HNTs) were functionalized using 3-aminopropyltriethoxysilane (APTES) and incorporated into polyethersulfone (PES) membranes to improve the hydrophilicity of the membranes as well as the interfacial interaction between HNTs and the polymer matrix. The intrinsic properties, permeability, and selectivity of the prepared membranes were analyzed to evaluate the membrane performance. In addition, humic acid (HA) fouling experiments were conducted to measure the antifouling properties of the fabricated membranes. As HNTs and functionalized HNTs (f-HNTs) contents are increased, hydrophilicity and mechanical strength were enhanced, and membranes with f-HNTs showed further improved performance. The pure water flux of membranes with 2% HNTs and f-HNT was 7.5 times higher than that of a pristine PES membrane without a trade-off relation between the water flux and HA rejection. The membranes with f-HNTs showed the highest antifouling properties compared to membranes with HNTs because enhanced hydrophilicity played a key role in preventing accumulation of HA. [ABSTRACT FROM AUTHOR]

We investigated the effect of Halloysite nanotube (HNT) addition on the interfacial and bending properties of hybrid composites. Test specimens were prepared using a vacuum bag method, which is manufactured by using an autoclave device. Ultrasound device was used to uniformly disperse HNT nanoparticles into the epoxy. Amount of the nanoparticles was determined by the weight of the epoxy resin. The Fracture toughness, ILSS and bending strength of Aramid/Basalt fiber hybrid composite specimens were decreased by more than certain amount of HNT. This phenomenon is presumably due to aggregation of HNT. [ABSTRACT FROM AUTHOR]

In order to overcome the weak bonding force between the interface of the composite materials, research for improving the interfacial bonding force by adding nanoparticles has been actively conducted. However, despite the improvement of characteristics through the addition of nanoparticles, it is not widely used because the particles are relatively expensive and it is difficult to control the aggregation between the particles. In this study, we compared the mechanical properties of relatively low-cost halloysite nanotube (HNT) nanoparticles with micro-sized milled carbon. Based on the similar mechanical properties of the composites with two particles added, we found that milled carbon could replace HNT particles. In addition, if the cohesion of HNT is reduced based on the strengthening effect of milled carbon having a relatively low cohesive strength, it is expected that the strengthening effect can be obtained more than that found in the existing studies. [ABSTRACT FROM AUTHOR]

Halloysite is a natural nanosized tubular clay mineral that has many potentially important uses in different industrial fields. In this paper, the key structural characteristics and properties of halloysite and their related applications are comprehensively reviewed. Research advances on halloysite, especially those from the past 20 years, are summarized with some critical comments. Attention is mainly paid to the structure and morphology of halloysite and their changes, the formation of tubular structures, the physicochemical properties, the surface chemical modifications, and the halloysite-based advanced materials and some related applications. Additionally, future prospects and key problems to be solved in halloysite studies are discussed. This review shed new light on both fundamental and applied studies that focused on halloysite. [ABSTRACT FROM AUTHOR]

• Negatively charged HNTs efficiently load 3 wt.% SrR by electrostatic interaction. • Drug loading could be stablished by zeta potential measurements. • SrR release proves the high permeability/degradability of gelatine-based coatings • Osteogenic differentiation are evident at the 7th day of immersion. Among strontium-based drugs, the Strontium ranelate (SrR) is a divalent strontium salt of ranelic acid which has an overall effect over the bone microarchitecture improvement. However, some findings reveal that the SrR affects in an opposite manner to the cell proliferation and osteoblastic differentiation, based on its concentration. Consequently, its release should be controlled. The incorporation of Halloysite nanotubes (HNT) as nanocarriers of SrR, into gelatine (GN) coatings, tailors the release of this anabolic bone-forming and anti-catabolic agent to stimulate bone growth. In fact, as-prepared GN/HNT-SrR coatings release 100 % SrR in phosphate buffered saline (PBS) within 21 days, and cellular studies of the nanocomposite coatings (MTT, Alkaline Phosphatase activity (ALP) and Calcium deposition assay) confirm the valuable bio-performance of these composite coatings to enhanced bone regeneration. In the present manuscript, suspensions with HNT/GN weight ratio of 0.5 are formulated to coat AISI 316 L stainless steel foils by Electrophoretic Deposition (EPD). Zeta potential determination is used to stablish the drug loading (HNT-SrR) by electrostatic interaction, as well as to optimize the dispersion of bare HNT and HNT SrR-loaded in a GN aqueous solution. Polyethilenimnine (PEI) is used as stabilizer to buffer the suspension media, assure cargo-drug dispersion and sequential release, while the thermal gelling of the suspension controls and step up the coating formation during EPD. [ABSTRACT FROM AUTHOR]