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A two-step methodology has been developed utilizing the models of Paul and Takayanagi to determine the modulus of polymer halloysite nanotube (HNT) products. Initially, HNTs and the adjacent interphase are considered as pseudoparticles, and their modulus is evaluated using the Paul model. Subsequently, the modulus of a nanocomposite, consisting of a polymer medium and pseudoparticles, is predicted by Takayanagi equation. The impacts of various factors on the modulus of the products are analyzed, and the results from the two-step method are compared with experimental data from different samples. It has been observed that the modulus of samples progressively increases with an increase in interphase depth. Also, a higher interphase modulus contributes to an enhanced modulus of samples. Nevertheless, excessively high interphase moduli (Ei > 60 GPa) result in only a marginal improvement in the modulus of nanocomposites. Additionally, narrower HNTs are advantageous for producing stronger samples, though the modulus of the nanocomposites slightly diminishes at very high HNT radii (R > 55 nm). The outputs of two-step method agree with the experimental moduli of various HNT-filled systems. [ABSTRACT FROM AUTHOR]

Using halloysite clay and vitamin B1 hydrochloride, a novel acidic halloysite-dendrimer catalytic composite has been developed for conversion of fructose to 5-hydroxymthylfurfural. To grow the dendritic moiety on halloysite, it was first functionalized and then reacted with melamine, epichlorohydrin and vitamin B1 hydrochloride respectively. Then, the resulting composite was treated with ZnCl2 to furnish Lewis acid sites. Use of vitamin B1 as the cationic moiety of ionic liquid obviated use of toxic chemicals and resulted in more environmentally friendly composite. Similarly, dendritic moiety of generation 2 was also grafted on halloysite and the activity of both catalysts for conversion of fructose to 5-hydroxymthylfurfural was investigated to disclose the role of dendrimer generation. For the best catalytic composite, the reaction variables were optimized via RSM and it was revealed that use of 0.035 g catalyst per 0.1 g fructose at 95 °C furnished HMF in 96% yield in 105 min. Turnover numbers (TONs) and frequencies (TOFs) were estimated to be 10,130 and 5788 h−1, respectively. Kinetic studies also underlined that Ea was 22.85 kJ/mol. The thermodynamic parameters of Δ H ≠ , Δ S ≠ and Δ G ≠ , were calculated to be 23 kJ/mol, − 129.2 J/mol and 72.14 kJ/mol, respectively. Notably, the catalyst exhibited good recyclability and hot filtration approved heterogeneous nature of catalysis. [ABSTRACT FROM AUTHOR]

NiO nanoparticles were assembled on the surface of Halloysite nanotubes, which were subsequently further functionalized by sulfonic acid, to create NiO@HNTs-SO3H composite. This composite is employed as a heterogeneous catalyst in the one-pot synthesis of 1-(benzothiazolylamino) methyl-2-naphthols starting from aryl aldehyde, β-naphthol and 2-aminobenzothiazole as well as Tetrahydrobenzo[b]pyrans starting from aldehyde, dimedone and malononitrile. The catalyst was examined using Fourier transform infrared (FT-IR), energy dispersive X-ray (EDX), X-ray diffraction (XRD) pattern, and scanning electron microscopy (SEM) images. The synthesized organic compounds were examined using 1H NMR and 13C NMR spectroscopy and mass analysis by HRMS. The most notable benefits of the current work are its straightforward setup, gentle reaction conditions, green solvents, excellent yields, ease of purification, high efficiency, and the use of a recoverable and environmentally friendly catalyst. The easy separation and reusability of NiO@HNTs-SO3H catalyst after five runs confirmed the stability and effectiveness of the catalyst. [ABSTRACT FROM AUTHOR]

This study is focused on the preparation of active packaging based on sodium caseinate (SC) and Rosa damascena essential oil (REO) reinforced by halloysite (Hal, 1 and 3 wt%) and bacterial cellulose (BC, 2 wt%). Based on FE-SEM images, the simultaneous incorporation of Hal and BC (BC2H3) could decrease a porosity of SC film and generate a homogenous surface, ascertaining well dispersion of reinforcements through the protein matrix. The porosity and non-homogeneity of the REO-loaded composites decreased in comparison with unloaded films due to the establishment of hydrogen bonding interactions. EDX mapping of Al and Si atoms proved the well distribution of halloysite into the SC film. While for REO-loaded nanocomposites, the aggregated regions enhanced by increasing the Hal content. XRD patterns of REO-bearing nanocomposites showed that the intensities of reflections belonging to Hal and BC decreased, indicating their increased amorphous structure. TG analysis indicated the improved thermal resistance of Hal-reinforced nanocomposites in comparison with the SC film. The thermal stability of nanocomposites showed insignificant change after addition of REO due to the presence of halloysite which could retard or delay the escape of EO molecules. Hal exhibited a more significant influence on tensile strength (TS) of the film as compared to BC. BC exhibited a more significant influence on barrier properties. The simultaneous incorporation of BC and Hal could compensate the decreased TS of REO-loaded films. The inclusion of REO into nanocomposites amplified their barrier and antibacterial properties. BC2H3/EO and BC2H1/EO nanocomposites satisfied the criteria of an ideal food packaging. [ABSTRACT FROM AUTHOR]

Polyelectrolytes with strong acidic functionality are among the prime sources for water desalination techniques. Poly 2‐acrylamido‐2‐methylpropanesulfonic acid (PAMPS) is one such polymer showing polyelectrolyte characteristics because of highly acidic SO3H group (pKa < 2) and film‐forming characteristics of flexible polymeric chains. Halloysite nanotubes functionalized with polyelectrolytes can be considered for water purification, as halloysite was reported to be efficient in removing dissolved metal salts. These polyelectrolytes can be introduced as a blend with other components, or they can be synthesized via in situ to form flexible membranes. Polymer nano‐filtration membranes with controlled crosslinking were designed as a function of halloysite and AMPS composition using in situ free radical polymerization with other polymers such as polyvinylidene fluoride and polyvinylpyrrolidone to strengthen the polymer matrix. The synthesized membranes were characterized using FTIR, SEM, EDS, TGA, and DTG techniques. Equilibrium water content, contact angle, water flux, salt rejection efficiency, and antifouling studies are also carried out for these membranes in water purification. [ABSTRACT FROM AUTHOR]

The removal of dyes from effluents of textile industries represents a technological challenge, due to their significant environmental impact. The application of halloysite (Hal) and palygorskite (Pal) clay minerals as adsorbents for the removal of Congo red (CR) and methylene blue (MB) was evaluated in this work. The materials were applied both in natural and acid-treated forms, and characterized by XRD, XPS, SEM–EDS, FTIR, and N2 adsorption–desorption isotherm techniques to identify their properties and main active sites. The adsorbents showed potential to remove CR (> 98%) and MB (> 85%) within 180 min, using 0.3 g adsorbent and initial dye concentration of 250 mg L−1. Semi-empirical quantum mechanical calculations (SQM) confirmed the interaction mechanism between dyes and the adsorbents via chemisorption (− 69.0 kcal mol−1 < Eads < − 28.8 kcal mol−1), which was further observed experimentally due to the high fit of adsorption data to pseudo-second order kinetic model (R2 > 0.99) and Langmuir isotherm (R2 > 0.98). The use of Pal and Hal to remove dyes was proven to be economically and environmentally viable for industrial application. [ABSTRACT FROM AUTHOR]

Membrane technology is known as one of the most efficient and extensive methods for oily wastewater treatment. In this research, polyvinyl chloride (PVC)-based mixed matrix membranes containing Uio66-NH2 nanoparticles and modified halloysite nanotubes (HNTs) were prepared using the phase inversion method. The synthesized membranes were characterized by field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and contact angle measurement analysis. Then, the effect of these nanoparticles was investigated for oil/water emulsion separation in the ultrafiltration process. To evaluate the prepared membranes, pure water flux, mean pore size, and oil separation ultrafiltration tests were performed. The results exhibited that addition of HNTs to the casting solution enhanced the pure water flux about up to 4 folds. Overall experimental results showed that due to the uniform distribution of halloysite nanotubes in sample 2, water contact angle decreased from 81° to 72°. UF results confirmed that sample 2 had the potential of rejecting 97% of sunflower oil. [ABSTRACT FROM AUTHOR]

Highlights In the current study, thermoset nanocomposites including halloysite nanotubes (HNTs) have been prepared through thiol‐epoxy click reaction at ambient conditions. Naturally available HNTs are first modified separately by epoxy and thiol groups and used as nanofillers in a mixture of trimethylolpropane triglycidyl ether and trimethylolpropane tris(3‐mercaptopropionate) ranging from 0 to 5 wt%. Fourier transformed infrared (FT‐IR) spectroscopy has been used to observe the characteristic bands of the pure and modified halloysite, neat thermoset, and HNT/thermoset nanocomposites. Thermal properties of epoxide‐modified and thiol‐modified halloysite nanotubes and also final thermoset nanocomposites have been investigated using thermogravimetric analysis (TGA) by comparing pure halloysite and neat thermoset, respectively. The dispersion of HNT nanotubes in thermoset matrix has been examined with scanning electron microscopy (SEM). In addition to the agglomerated/non‐agglomerated distribution, the present of HNT has been proved by EDX. The effect of HNT‐Epoxide and HNT‐Thiol loadings on mechanical properties has been examined by tensile test. All nanocomposites were found to exhibit better tensile strength than that of neat thermoset, called as reference sample. The most enhanced mechanical properties have been detected in the nanocomposite with 3% modified‐HNTs by weight because of the best dispersion, which promotes effective interactions between the nanotubes and thermoset matrix. Tensile strength of thermoset nanocomposites increased by 43% and 62%, while elongation at break increased by 58% and 149% when 3 wt% HNT‐Epoxide and 3 wt% HNT‐Thiol were added to the matrix, respectively. Further increase of HNT added to the matrix causes agglomeration of nanotubes and thus deterioration of mechanical properties. Pure HNT was modified and successfully converted into HNT‐Epoxide and HNT‐Thiol. In‐situ preparation of thermoset nanocomposites with modified‐HNTs was effectively achieved via thiol‐epoxy click chemistry. Mechanical properties increased significantly with both HNT‐Epoxide and HNT‐Thiol loading ratio up to 3 wt%. The presence and agglomerated/non‐agglomerated dispersion of modified‐HNTs in the thermoset matrix were verified by SEM–EDX analysis. [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]

The reaction steps involved in the 5‐hydroxymethylfurfural to 2,5‐furandicarboxylic acid conversion by means of H2O2 were investigated employing a dedicated computational protocol based on density functional theory. The catalytic environment of choice was a molecular model representing a portion of the halloysite nanotube outer surface, functionalized by an organosilane, the 3‐aminopropyltriethoxysilane, whose amino group bonds one gold atom. At this stage of the investigation, the process was fully detailed in terms of the interactions between the reaction intermediates and the catalyst, and the reaction standard free energies. In addition, the energy barriers of the elementary steps involving the hydrogen migration from the adsorbed organic species to the gold atom were analyzed. On the basis of the interaction geometries, a certain distinction among the preferred reaction path can be inferred as a function of the net negative charge characterizing the catalyst outer surface. Since the inner surface of halloysite can represent the acid environment needed to obtain 5‐hydroxymethylfurfural through dehydration of fructose, the present study is framed in a wider research field where the possibility to consider functionalized halloysite as one‐pot reactor for the valorization of biomass is explored. [ABSTRACT FROM AUTHOR]

Molecules confined within nanometer‐scale environments frequently exhibit a distinct physical response in contrast to those found in bulk conditions. In this study, intercalates of lauric acid (LA) are synthesized within halloysite nanotubes (HNT), successfully trapping 12 wt.% of LA within the internal HNT tube, as demonstrated by transmission electron microscopy (TEM), and wide‐angle and small‐angle X‐ray scattering (WAXS/SAXS) techniques. Furthermore, it is noted that the confinement of LA within the HNT lumen resulted in a significant reduction in LA crystallinity, consistent with the impact of geometric constraints on crystallization behavior. The presence of a significant amorphous phase in the intercalates proved beneficial for the gradual release of LA into water, as evidenced by pH changes. Remarkably, the necessity of employing a vacuum method and extended contact time (72 h) for the physical entrapment of LA in ethanol within the HNT lumen is found to be unnecessary, as similar physical characteristics are observed in an intercalate generated without vacuum and with very short contact time (<1 h). Finally, it is observed that the source of HNT is crucial in determining the final properties of the confined material. [ABSTRACT FROM AUTHOR]

Metalized plastic current collectors (MPCCs) have shown potential in improving the energy density and safety of lithium‐ion batteries (LIBs). However, the poor mechanical strength, weak interfacial adhesion force, and surface metal corrosion have impeded the practical application of MPCCs. Here, an innovative engineering of MPCCs is proposed by incorporating halloysite nanotubes (HNTs) as fillers into polyimide (PI) polymer layer, which is further coated with two thin copper (Cu) layers. Because of the strong bonding between HNTs surface and the PI precursor, HNTs improve the mechanical strength of PI‐HNTs composite film, reinforce the interfacial adhesion force between the PI‐HNTs film and the coated Cu layer, and suppress the Cu corrosion by electrolyte. The prepared MPCCs exhibit a low mass density and only account about one‐fifth of the density of commercial Cu CCs. Furthermore, the PI‐HNTs‐Cu composite demonstrates significantly enhanced interfacial adhesion force doubled to 4 N cm−1 along with prolonged stability under electrolyte immersion and electrochemical reaction conditions, and delivers a high fracture strength of 125 MPa. LIBs assembled with MPCCs deliver a twice higher discharge capacity compared to battery with Cu CCs and reach a long‐term cycle capacity retention as high as 92.9% at 0.5 C after 500 cycles. [ABSTRACT FROM AUTHOR]

Currently, there are few reports of core–shell‐structured smoke suppressants that can provide a growth substrate and stabilize the char layer. In response to this problem, core–shell nanoparticles of halloysite nanotubes (HNTs) coated with copper itaconate complex were prepared by layer‐by‐layer assembly method. The electrostatic forces between HNTs and copper ions and the coordination between the itaconic acid and copper ions contributed this synthesis. The micromorphology, chemical composition, and structure of HNT@CuC5H4O4 were characterized, and its effects on the flame‐retardant and smoke‐inhibition properties, mechanical properties, and thermal stability of the soft polyvinyl chloride (PVC) were investigated. The results showed that the core–shell structure of HNT@CuC5H4O4 contributed to its homogeneous dispersion in PVC and the formation of interlocking mesh structure. Thus, the incorporation of HNT@CuC5H4O4 enhanced the strength and stiffness of soft PVC without sacrificing its ductility. Besides, copper ions on HNT@CuC5H4O4 could promote the cross‐linking carbonization of the PVC at high temperature. The formed char layer catalyzed by CuC5H4O4, together with its attached three‐dimensional network structure of HNT constituted a compact and continuous char layer with high thermal stability, which effectively prevented the release of combustible volatiles and toxic gases as well as heat transfer. [ABSTRACT FROM AUTHOR]

Background: Polymethylmethacrylate (PMMA) bone cement is used in orthopedics and dentistry to get primary fixation to bone but doesn't provide a mechanically and biologically stable bone interface. Therefore, there was a great demand to improve the properties of the PMMA bone cement to reduce its clinical usage limitations and enhance its success rate. Recent studies demonstrated that the addition of halloysite nanotubes (HNTs) to a polymeric-based material can improve its mechanical and thermal characteristics. Objectives: The purpose of the study is to assess the compressive strength, flexural strength, maximum temperature, and setting time of traditional PMMA bone cements that have been manually blended with 7 wt% HNT fillers. Methods: PMMA powder and monomer liquid were combined to create the control group, the reinforced group was made by mixing the PMMA powder with 7 wt% HNT fillers before liquid mixing. Chemical characterization of the HNT fillers was employed by X-ray fluorescence (XRF). The morphological examination of the cements was done using a scanning electron microscope (SEM). Analytical measurements were made for the compressive strength, flexural strength, maximum temperature, and setting time. Utilizing independent sample t-tests, the data was statistically assessed to compare mean values (p < 0.05). Results: The findings demonstrated that the novel reinforced PMMA-based bone cement with 7 wt% HNT fillers showed higher mean compressive strength values (93 MPa) and higher flexural strength (72 MPa). and lower maximum temperature values (34.8 °C) than the conventional PMMA bone cement control group, which was (76 MPa), (51 MPa), and (40 °C), respectively (P < 0.05). While there was no significant difference in the setting time between the control and the modified groups. Conclusion: The novel PMMA-based bone cement with the addition of 7 wt% HNTs can effectively be used in orthopedic and dental applications, as they have the potential to enhance the compressive and flexural strength and reduce the maximum temperatures. [ABSTRACT FROM AUTHOR]

The goal of this work is to investigate the mechanical and fracture characteristics of polylactic acid (PLA)/thermoplastic polyurethane (TPU)/halloysite (HNT). HNT with three levels (0, 3, and 6 wt.%) and TPU with three levels (10, 20, and 30 wt.%) were used as variables. The investigation of tensile properties revealed contrasting effects of TPU and HNT levels. Increasing TPU content to 30 wt.% led to a decrease in strength and modulus by 36% and 42% in turn, however resulted in a remarkable 338% improvement in elongation at break. Conversely, the addition of 3 wt.% HNT enhanced both tensile strength and modulus, although it caused a reduction in elongation at break. The results concerning fracture properties showed by incorporating TPU up to 30 wt.% EWF (w e ) and non-EWF (βw p ) rose by 459% and 178%, respectively. Additionally, the inclusion of 3 wt.% HNT further elevated the EWF compared to the compound containing 10 wt.% TPU without HNT. Through optimization, the compound with 10 wt.% TPU and 3 wt.% HNT was shown to have the optimum strength, stiffness, and toughness balance. [ABSTRACT FROM AUTHOR]

This paper presents the results of borehole investigations and laboratory tests carried out to characterize the soils derived from in situ weathering of tuff in Central Java, Indonesia. The 70 m thick weathering profile of the Quaternary tuff consisted of residual soil and completely to highly decomposed rocks. The relatively low dry unit weight and cohesion but high water content, porosity, plastic and liquid limits, and angle of internal friction of the soils in the present study were related to the dominance of halloysite clay minerals. The established relationships to predict soil shear strength parameters from the soil plasticity index and standard penetration test (SPT) N-values were examined, and linear and non-linear relationships for soils derived from in situ weathering of tuff were proposed. [ABSTRACT FROM AUTHOR]

In this article, the suitability of utilization of porous lumen structure of Halloysite (Hal) nanoclay has been studied elaborately. To utilize the lumen structure for membrane development, the effect of temperature, pressure and time on the porous lumen feature and subsequent use of the clay in pristine form as a membrane coating material for separation purposes at specified temperatures shows the importance of this study. The present study investigates structural changes in Halloysite nanoclay's inherent porous tubular morphology. Membranes are prepared by coating clay-alumina porous support tube with Halloysite sol under pressure and temperature of 100 and 160 °C for 24, 48 and 64 h, respectively. XRD and FTIR reveal that the tubular structure remains intact under experimental conditions. In contrast, the morphology of pristine Hal powder treated at the specified temperature and under in situ developed autogenous pressure shows a significant textural change in the nanotubular morphology observed from FESEM. At 100 °C, lumen porosity remains intact, but at 160 °C, under higher pressure, lumen mouth sealing, conjoining and coalescence of the halloysite nanotubes (HNT) result. In addition, for both temperatures under existing operating pressure, the effect of 24 h time duration on morphology is less. For practical viability, a preliminary study for dye removal is carried out with H1 membrane coating, which shows promising %rejection values. This study on powders and membrane coatings might thus help to assign new application fields, such as membrane-based separation utilizing the porous nature of HNT by controlling different process parameters. [ABSTRACT FROM AUTHOR]

Highlights Polymer nanocomposites have found wide industrial applications, necessitating optimal mechanical and fracture properties evaluation, traditionally done through costly experimental methods. This study employs machine learning, particularly XGBoost, to predict properties like tensile and fracture properties swiftly, aiding material innovation across industries. The research investigates unvulcanized and vulcanized polypropylene (PP)/ethylene propylene diene monomer (EPDM) reinforced with clay and halloysite nanoparticles (HNT), analyzing fracture properties via essential work of fracture (EWF). Experimental design selects tests, and an XGBoost model predicts tensile strength and modulus, strain at break, EWF, and non‐EWF based on EPDM and nanoparticle percentages, composite and nanoparticle types. The model accurately predicts tensile strength and modulus but less so for strain at break, EWF, and non‐EWF. Mean Absolute Percentage Error values for training/test are 0.49/1.21, 1.05/1.55, 34.21/42.76, 3.02/14.35, and 2.89/3.78, with determination coefficients of 0.99/0.98, 0.99/0.97, 0.97/0.91, 0.97/0.79, and 0.92/0.73. Nanoparticles mainly affect outputs, with EPDM secondarily impactful, while composite and nanoparticle types exhibit similar significance. The best‐performing polymer nanocomposite is a dynamically vulcanized one containing 10 wt% EPDM and 3 wt% clay, achieving tensile strength of 25.070 MPa, tensile modulus of 261.170 MPa, EWF of 75.300 N/mm, and non‐EWF of 10.150 N/mm2. The effects of ethylene propylene diene monomer (EPDM), clay and halloysite nanoparticles on the mechanics of polypropylene‐based nanocomposites. Essential work of fracture (EWF) was used to study the fracture properties. Machine learning was employed to predict all mechanical characteristics. The vulcanization process improved all mechanical characteristics. The best compound: vulcanized one containing 10 wt% EPDM and 3 wt% clay. [ABSTRACT FROM AUTHOR]

One solution to comply with the strict regulations of the European Commission and reduce the environmental footprint of composites is the use of composite materials based on bio-polymers and fillers from natural resources. The aim of our work was to obtain and analyze the properties of bio-polymer nanocomposites based on bio-PA (PA) and feather keratin–halloysite nanohybrid. Keratin (KC) was mixed with halloysite (H) as such or with the treated surface under dynamic conditions, resulting in two nanohybrids: KCHM and KCHE. The homogenization of PA with the two nanohybrids was conducted using the extrusion processing process. Two types of nanocomposites, PA–KCHM and PA–KCHE, with 5 wt.% KC and 1 wt.% H were obtained. The properties were analyzed using SEM, XRD, FTIR, RAMAN, TGA, DSC, tensile/impact tests, DMA, and nanomechanical tests. The best results were obtained for PA–KCHE due to the stronger interaction between the components and the uniform dispersion of the nanohybrid in the PA matrix. Improvements in the modulus of elasticity and of the surface hardness by approx. 75% and 30%, respectively, and the resistance to scratch were obtained. These results are promising and constitute a possible alternative to synthetic polymer composites for the automotive industry. [ABSTRACT FROM AUTHOR]

Polybutylene terephthalate (PBT) nanocomposites were melt-blended with two types of Turkish halloysite nanotubes (HN). Naturally occurring HN samples were used to produce PBT-based composites at the HN compositions of 1%, 3%, 5%, and 10%. Findings of neat and silane-coated HN-containing composite samples were compared to investigate the interfacial adhesion between polymer matrix and reinforcement material. According to test results, a 1% amount of HN was found to be the most suitable option in the case of mechanical and thermal properties of composites. Additionally, silane-modified grade displayed highly indicative improvements compared to pristine HN clay due to better interfacial adhesion of halloysite nanotubes to the PBT matrix was accomplished. Property enhancements achieved for composite samples containing low contents of HN were confirmed by morphological examinations. As a result, the PBT/ 1% HN-S composite sample was bookmarked as the most suitable option to fabricate HN-reinforced PBT-based nanocomposites in terms of mechanical, thermo-mechanical, morphological, thermal, and physical performances based on the findings in this study. Silane-modified halloysite grades exhibited better results, and they were found to be more suitable in the case of applications of PBT. [ABSTRACT FROM AUTHOR]

With the ever‐increasing need for energy storage devices with high energy density, lithium (Li) metal anodes have been revisited. Due to the high reactivity of Li metal and the safety issues associated with liquid electrolytes, solid polymer electrolytes (SPEs) have gain attention. Polyethylene oxide (PEO) with the highest ionic conductivity (σ) among the polymers faces serious problems. The inability to meet the practical limit of σ due to its high crystallinity, and its low thermomechanical stability above its melting temperature, have limited its large‐scale application. In this research, anionic polyurethane dispersion (PUD) based on poly (ε‐caprolactone) (PCL) was synthesized and different PUD:PEO compositions was prepared using water as a solvent. Halloysite nanotube (HNT) was also used to improve the ionic conductivity by providing a new pathway for conducting lithium ions in the composition. The results corroborated that the presence of PUD stabilized the storage modulus of the host polymer above Tm of PEO. The ionic nature of the selected PUDs resulted in a transference number of 0.59 and the presence of HNT increased this value to 0.72. The presence of HNTs also led to a significant increase in σ by about three times compared to the control sample. [ABSTRACT FROM AUTHOR]

A series of halloysite nanotube‐silica (HNTs‐SiO2) nanocomposite fillers were prepared by in‐situ assembly, and a reinforced SiO2/SR composite was obtained by filling them into silicone rubber (SR). The morphology and structural characterization of HNTs‐SiO2 and HNTs‐SiO2/SR and the properties of the HNTs‐SiO2/SR were studied. As a result, the small particle size SiO2 was firmly anchored onto the HNTs surface, and the obtained HNTs‐SiO2 nanofillers were uniformly dispersed in SR. At a 30 phr fixed filler loading, the weakest filler network and the best filler dispersion were obtained when HNTs content in HNTs‐SiO2 was 5%. This resulted in a maximum tensile strength obtained of 6.2 MPa, 1.55 times that of SiO2/SR with the same filler loading, and a maximum elongation at break of 418%, 1.67 times that of the SiO2/SR with the same filler loading, and at the same time the tearing strength and hardness are also improved. Furthermore, the silicone rubber also showed improved thermal stability, with an initial degradation temperature increase of 30°C under a nitrogen atmosphere. Highlights: HNTs–SiO2 nanocomposites were successfully prepared by the self‐assembly method and used as fillers in SR as a new type of reinforcing material.The 1D HNTs act as a barrier to prevent SiO2 aggregation and improved fillers dispersion.The elongation at break and tensile strength of 5% HNTs‐SiO2/SR are 67% and 55% higher than those of SiO2/SR, respectively.The silicone rubber also showed improved thermal stability. [ABSTRACT FROM AUTHOR]

In situ formation of carbon dots on halloysite nanotubes is demonstrated by treating polyacrylamide-grafted halloysite nanotubes with polycarboxylic acid without the recourse to extremely high temperatures or solvents. Thermosensitive luminescence and phosphorescence properties are carefully investigated. The polyacrylamide-grafted halloysite nanotubes are further processed as composite films for encryptable thermal printing. [ABSTRACT FROM AUTHOR]

Chemical modification of the surface of halloysite nanotubes (HNT) by alkalization (with sodium hydroxide (NaOH)) and grafting with silanes (bis(trimethylsilyl)amine (HMDS)) was carried out. The efficiency of the alkalization and grafting process was evaluated by X–ray diffraction (XRD), Fourier–transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and the nitrogen adsorption method were used. XRD and FTIR analysis confirmed the formation of bonds of trimethylsilyl groups to the HNT surface which changed the nature of the surface from hydrophilic to hydrophobic. In addition, it was noted that grafting with silanes decreases by 7.2% the specific surface area of the halloysite compared to the alkalized material. High–density polyethylene (HDPE) composites with halloysite (HNT), alkalized halloysite (alk–HNT), and HMDS–modified halloysite (m–HNT) were processed in the molten state in a Brabender mixer chamber. On SEM/EDS micrographs of HDPE composites with silanized HNT, a change in surface characteristics from smooth to ductile was observed. Higher melting point values based on differential scanning calorimetry (DSC) analysis of HDPE composites with 5%wt silanized halloysite in comparison with HNT and alk–HNT of, respectively, 2.2% and 1.4% were found, which indicates a slight beneficial influence of the filler on the quality of ordering of the crystalline phase of the matrix. [ABSTRACT FROM AUTHOR]

The adsorption of copper ions and Reactive Red 120 azo dye (RR-120) as models of water pollutants on unmodified halloysite (H-NM), as well as halloysites modified with sulfuric acid (H-SA) and (3-aminopropyl) triethoxysilane (H-APTES), was investigated. The results showed that adsorption of both the adsorbates was pH-dependent and increased with the increase in halloysite dosage. The adsorption kinetics were evaluated and the results demonstrated that the adsorption followed the pseudo-second-order model. The adsorption isotherms of Cu(II) ions and RR-120 dye on the halloysites were described satisfactorily by the Langmuir model. The maximum adsorption capacities for the Cu(II) ions were 0.169, 0.236, and 0.507 mmol/g, respectively, for H-NM, H-SA, and H-APTES indicating that the NH2-functionalization rather than the surface area of the adsorbents was responsible for the enhanced adsorption. The adsorption capacities for RR-120 dye were found to be 9.64 μmol/g for H-NM, 75.76 μmol/g for H-SA, and 29.33 μmol/g for H-APTES. The results demonstrated that APTES-functionalization and sulfuric acid activation are promising modifications, and both modified halloysites have good application potential for heavy metals as well as for azo dye removal. [ABSTRACT FROM AUTHOR]

Recent research is shifting towards adopting recyclable and sustainable plastics instead of traditionally used thermosetting materials. Accordingly, vitrimers behave both as thermoplastics as well as thermosetting polymers. Inimitable vitrimer polymers have been developed with dynamically crosslinked structures enhancing the durability, reprocessing, and mechanical and chemical stability features. This state-of-the-art review discusses vitrimer nanocomposites reinforced with carbonaceous (carbon nanotube, graphene, and graphene oxide) and inorganic (silica, halloysite nanotube) nanofillers has been particularly emphasized. Beneficial structural, microstructural, mechanical strength, modulus, thermal, conducting, reprocessing, engineering, shape memory, self-healing, kinetic, and theoretical topographies have been observed with vitrimers or modified vitrimers (disulfide or ether functional) matrices along with nano-reinforcements towards multifunctional architectures. High-tech vitrimeric nanocomposites show potential regarding electromagnetic shielding, anticorrosion coatings, sensors, joints welding, adhesives, and other sectors. Versatile design compensations, degradability, reprocessability, and methodological features/applications point towards next-generation sustainable materials for modern industries. Hence, this article presents advancements in the field of high performance vitrimeric nanocomposites. [ABSTRACT FROM AUTHOR]

The effect of the preparation protocol of chitosan (CHI) based films filled with wax microparticles stabilized by halloysite nanotubes (HNTs) in Pickering emulsions (PE) is investigated. The obtained results show that the addition of acetic acid (before or after the preparation of wax/HNT microspheres) affects the properties of the composite films as well as the colloidal stability of PE. The colloidal behavior of CHI/HNT/wax PE by optical microscopy and sedimentation tests are studied. On the other hand, the corresponding composite films (prepared by solvent casting method) are characterized through several techniques, including Scanning Electron Microscopy, UV–vis spectrometer, water permeability, and contact angle measurements. Dynamic Mechanical Analysis allows this to estimate the effect of wax microparticles on the tensile performances of CHI‐based films. As a general consideration, the filling of the CHI matrix with wax/HNT improves the physicochemical properties of the films. Finally, the efficacy of the films as adsorbents of n‐dodecane vapors is explored. Due to the presence of hydrophobic domains (wax embedded in CHI), the composite films possess higher adsorption efficiencies compared to pristine CHI. Accordingly, it can be stated that the combination of CHI with wax/HNT microparticles is promising to obtain biocompatible composite films useful for remediation purposes. [ABSTRACT FROM AUTHOR]

Nanoclays are a class of nanomaterials extensively used to prepare polymer nanocomposites. In this study, four types of common nanoclays were selected to prepare chitosan–polyvinyl alcohol (CP) nanocomposite films. Montmorillonite cloisite Na+ (MMT), organically modified montmorillonite (OMMT), and bentonite (BNT), as layered aluminosilicates, and halloysite nanotubes (HNT), as a tubular nanoclay, were blended with CP films at concentrations of 1.5, 3 and 4.5%. The nanocomposite films were characterized by FTIR, XRD, SEM/EDX, AFM, tensile strength, and antibacterial tests. SEM/EDX results showed a more uniform distribution of the OMMT and HNT nanoclays in the polymer matrix. AFM images showed a rougher surface for nanocomposite films compared to CP film. Increasing the nanoclay concentration in the films from 1.5 to 4.5% resulted in higher tensile strength for HNT and MMT while the trend was reversed for OMMT and BNT. Among the samples, nanocomposite films composed of OMMT and BNT showed the highest tensile strength at the lowest concentrations (CP-OMMT1.5 99 ± 3.7 MPa, CP-B1.5 81 ± 1.5 MPa). The nanocomposite films prepared from OMMT showed the highest antibacterial activity against E. coli and S. aureus with an inhibition zone of 15 and 19 mm, respectively. The results of this study showed that BNT and OMMT are promising nanoclays for enhancing the mechanical properties and antibacterial activity of hydrophilic polymers. The results of this research can provide new insights into selecting suitable nanoclays for different applications. [ABSTRACT FROM AUTHOR]

The photosensitive pharmaceutical ingredient moxifloxacin hydrochloride degrades during storage under the influence of external factors, such as elevated temperature and ultraviolet and visible light irradiation, resulting in a decrease in the concentration of the active substance. To increase its resistance to these external factors, moxifloxacin hydrochloride was encapsulated in halloysite nanotubes. The aim of this study was to determine the level of degradation of moxifloxacin hydrochloride in its native and encapsulated states under the influence of temperature and ultraviolet and visible light irradiation. Encapsulation was carried out by the vacuum method and confirmed by TEM microscopy. The residual content of the photosensitive pharmaceutical ingredient after degradation was monitored by high-performance liquid chromatography of a model solution with an initial concentration of 2 mg/ml, prepared from samples of native and encapsulated moxifloxacin hydrochloride previously tested under the influence of temperature and light irradiation. Encapsulated moxifloxacin hydrochloride showed increased resistance to degradation caused by visible light irradiation at 200 watt-hours/m² (by 10.9%); resistance to degradation was increased by 13.4% and 14% under test conditions during 24 hours of ultraviolet light irradiation and thermostating at a temperature of 60°C, respectively, compared to non-encapsulated moxifloxacin hydrochloride. [ABSTRACT FROM AUTHOR]

Abstract Using halloysite clay and vitamin B1 hydrochloride, a novel acidic halloysite-dendrimer catalytic composite has been developed for conversion of fructose to 5-hydroxymthylfurfural. To grow the dendritic moiety on halloysite, it was first functionalized and then reacted with melamine, epichlorohydrin and vitamin B1 hydrochloride respectively. Then, the resulting composite was treated with ZnCl2 to furnish Lewis acid sites. Use of vitamin B1 as the cationic moiety of ionic liquid obviated use of toxic chemicals and resulted in more environmentally friendly composite. Similarly, dendritic moiety of generation 2 was also grafted on halloysite and the activity of both catalysts for conversion of fructose to 5-hydroxymthylfurfural was investigated to disclose the role of dendrimer generation. For the best catalytic composite, the reaction variables were optimized via RSM and it was revealed that use of 0.035 g catalyst per 0.1 g fructose at 95 °C furnished HMF in 96% yield in 105 min. Turnover numbers (TONs) and frequencies (TOFs) were estimated to be 10,130 and 5788 h−1, respectively. Kinetic studies also underlined that Ea was 22.85 kJ/mol. The thermodynamic parameters of $$\Delta {\text{H}}^{ \ne }$$ Δ H ≠ , $$\Delta {\text{S}}^{ \ne }$$ Δ S ≠ and $$\Delta {\text{G}}^{ \ne }$$ Δ G ≠ , were calculated to be 23 kJ/mol, − 129.2 J/mol and 72.14 kJ/mol, respectively. Notably, the catalyst exhibited good recyclability and hot filtration approved heterogeneous nature of catalysis.

Abstract Background Polymethylmethacrylate (PMMA) bone cement is used in orthopedics and dentistry to get primary fixation to bone but doesn’t provide a mechanically and biologically stable bone interface. Therefore, there was a great demand to improve the properties of the PMMA bone cement to reduce its clinical usage limitations and enhance its success rate. Recent studies demonstrated that the addition of halloysite nanotubes (HNTs) to a polymeric-based material can improve its mechanical and thermal characteristics. Objectives The purpose of the study is to assess the compressive strength, flexural strength, maximum temperature, and setting time of traditional PMMA bone cements that have been manually blended with 7 wt% HNT fillers. Methods PMMA powder and monomer liquid were combined to create the control group, the reinforced group was made by mixing the PMMA powder with 7 wt% HNT fillers before liquid mixing. Chemical characterization of the HNT fillers was employed by X-ray fluorescence (XRF). The morphological examination of the cements was done using a scanning electron microscope (SEM). Analytical measurements were made for the compressive strength, flexural strength, maximum temperature, and setting time. Utilizing independent sample t-tests, the data was statistically assessed to compare mean values (p

In this study, PMMA/Bentonite and PMMA/HNT nanocomposites were synthesized by in-situ and solution blending methods by using polymethyl methacrylate (PMMA) obtained from methyl methacrylate by emulsion polymerization method and bentonite and halloysite (HNT) at different ratios (5 wt.% and 10 wt.%). Biodegradable PMMA/PLA, PMMA/PLA/Bentonite, and PMMA/PLA/HNT were obtained by mixing the synthesized PMMA and PMMA/clay nanocomposites with a polylactic acid (PLA) with PMMA:PLA weight ratio of 50:50. Characterization studies of synthesized nanocomposites; Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Scanning Electron Microscope (SEM) analyzes, and Shore-D hardness test was performed. In addition, to observe the effects of clay additives and production methods on biodegradability, the synthesized samples were buried in two different soils, humus soil and cactus soil, and monitored for six months. When the obtained nanocomposites were compared with the pure polymer, it was determined that the hardness values of the nanocomposites were much higher than the pure polymer, and their thermal stability increased with HNT and bentonite additives. When nanocomposites synthesized by the in-situ production method and solution blending production method are compared, it was determined that nanocomposites produced by the solution blending method degrade faster in the soil and show better distribution in the structure. In addition, it was observed that cactus soil created a better degradation environment than humus soil, and bentonite accelerated degradation more than HNT. [ABSTRACT FROM AUTHOR]

Abstract The aim of this research is to synthesize a new sulfonic acid catalyst based on halloysite nanotubes (Hal-Py-SO3H) and characterize it as a solid acid nanocatalyst by various analytical techniques such as Fourier-Transformed Infrared spectroscopy (FTIR), Thermal gravimetric Analysis (TGA), X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Vibrating Energy-Dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and X-ray atomic mapping. Furthermore, this new catalyst was evaluated in synthesizing spiropyran derivatives via multicomponent reactions (MCRs) and Xanthen derivatives under environmentally sustainable conditions. The main advantages of this approach include green conditions, excellent yields, quick reaction rates, and ease of preparation. Additionally it was observed that the catalyst exhibited robust stability even after multiple recycling processes, indicating its potential for practical applications in sustainable chemical transformations.

Highlights In this study, we compare synergistic performance of two different nanofillers, namely halloysite nanotubes (HNT) clay and multiwalled carbon nanotubes (MWCNT), in conjunction with a fixed concentration (0.125 phr) of semi‐anthracite coal‐derived graphene oxide (AC‐GO) on mechanical properties improvement of EGFPs (E‐glass fiber‐based epoxy resin composites). The dispersion of AC‐GO with HNT clay (GO‐H) and AC‐GO with MWCNT (GO‐C) within epoxy matrix was achieved using sonication and homogenization. Further mixture was incorporated into mats of E‐glass fiber employing “vacuum‐assisted resin infusion molding” (VARIM). Significant enhancements (18.3% flexural strength, 14.6% tensile strength, and a slight increase of impact strength (1.8%)) were observed in EGFPs reinforced with GO‐H at 0.50 phr loading of HNT, with an AC‐GO concentration maintained at 0.125 phr. Correspondingly, optimal values for GO‐C reinforced EGFPs at 0.25 phr were 40.3%, 18.7%, and a 10.5% decrease in impact strength, respectively. Analytical techniques such as XRD, FESEM, EDX mapping, and FTIR reveal presence of relatively abundant functionalities and strong interfacial adhesion in GO‐H as well as GO‐C. The cost of HNT clay is approximately 15 times cheaper than industrial‐grade MWCNTs, therefore, these results underscore potential of GO‐H as a very economical nano‐reinforcement alternative to GO‐C for polymer nanocomposites. 0.50 phr HAGRP improves 18.3% flexural, 14.6% tensile, 1.8% impact strengths. Beyond 0.50 phr HAGRP and 0.25 phr CAGRP, mechanical properties decreased. 0.25 phr CAGRP improves 40.3% flexural, and18.7% tensile strengths. FESEM, FTIR reveal strong interfacial adhesion between nanofillers and epoxy. GO‐H has proven to be an inexpensive reinforcement for polymer nanocomposites. [ABSTRACT FROM AUTHOR]

A hybrid of halloysite nanotubes decorated with titanium dioxide nanoparticles (HNTs@TiO2) was synthesized by the sol–gel method and then mixed with ultra‐high molecular polyethylene (UHMWPE) by melt compounding to enhance its wear resistance properties. The incorporation of HNTs@TiO2 increased the crystallinity as well as the hardness of UHMWPE nanocomposites, which benefited less prone to plastic deformation during the friction process. In addition, the UHMWPE/HNTs@TiO2 maintained a high ductility character with a slight decrease in tensile strength compared to pure UHMWPE. With the addition of 3 wt% HNTs@TiO2, the UHMWPE nanocomposite achieved a remarkably low friction coefficient of 0.073 and a reduced wear rate of 6.67 × 10−6 mm3/N·m. These values represented a 32.4% decrease in friction coefficient and a 43.9% decrease in wear rate compared to pure UHMWPE. The improvement in wear resistance was due to the dislodged TiO2 and HNTs had good synergistic rolling effects at the counterface. Furthermore, the wear scan morphology observation revealed that the transferred HNTs@TiO2‐based materials could help to improve the quality of the tribofilms, which alleviated the abrasive wear from the metallic counterpart. This work offers a feasible way to enhance the wear resistance of UHMWPE nanocomposite without sacrificing the high ductility for expanding its engineering applications. Highlights: TiO2‐decorated halloysite nanotubes were synthesized by the sol–gel method.The addition of HNTs@TiO2 maintained the high ductility character of UHMWPE.The UHMWPE composite with 3 wt% HNTs@TiO2 had the best wear resistance. [ABSTRACT FROM AUTHOR]

Antibiotics have been established to induce indiscriminate detrimental effects on the gut commensal bacteria which are vital for human health. This study unprecedently reports the mitigation of this challenge through the targeted delivery of antibiotics to a specific intestinal model pathogen using naturally occurring nanoclay. The designed Halloysite nanotubes targeting (HaNTr) system employs intrinsically mesoporous clay particles, functionalized with antibodies against Escherichiacoli (E. coli). Loaded with the antibiotic ciprofloxacin (CIP), the HaNTr particles demonstrate enhanced selectivity of their payload in a human microbiome ex vivo system, preserving the composition of non‐target populations. Furthermore, the HaNTr system exhibits up to a 10‐fold increase in selectivity against E. coli, compared to neat CIP, in a heterogenous culture. This enhanced selectivity is attributed to the sustained and localized release of CIP from the HaNTr particles (≈0.8 ng CIP min−1 mg−1), following their specific binding to target bacteria, as quantitatively measured by high‐throughput imaging flow cytometry. Importantly, HaNTr particles are also shown to be biocompatible with Caco‐2 cells, mimicking the intestinal epithelium. This work highlights the prominent capability of the HaNTr system in alleviating antibiotic‐associated dysbiosis by the targeted delivery of antimicrobials to potentially any microorganism against which the immobilized capture probe can be customized. [ABSTRACT FROM AUTHOR]

Despite the mechanical and physical properties of polyurethane foams (PUF), their application is still hindered by high inflammability. The elaboration of effective, low-cost, and environmentally friendly fire retardants remains a pressing issue that must be addressed. This work aims to show the feasibility of the successful application of natural nanomaterials, such as halloysite nanotubes and nanocellulose, as promising additives to the commercial halogen-free, fire-retardant triphenyl phosphate (TPP) to enhance the flame retardance of open-cell polyurethane foams. The nanocomposite foams were synthesized by in situ polymerization. Investigation of the mechanical properties of the nanocomposite PUF revealed that the nanoscale additives led to a notable decrease in the foam's compressibility. The obtained results of the flammability tests clearly indicate that there is a prominent synergetic effect between the fire-retardant and the natural nanoscale additives. The nanocomposite foams containing a mixture of TPP (10 and 20 parts per hundred polyol by weight) and either 10 wt.% of nanocellulose or 20 wt.% of halloysite demonstrated the lowest burning rate without dripping and were rated as HB materials according to UL 94 classification. [ABSTRACT FROM AUTHOR]

The development of eco-friendly, mechanically stable, and biocompatible materials for medical packaging has gained significant attention in recent years. Halloysite nanotubes (HNTs) have emerged as a promising nanomaterial due to their unique tubular structure, high aspect ratio, and biocompatibility. We aim to develop a novel soybean oil-based thermoset bio-resin incorporating HNTs and to characterize its physical and functional properties for medical packaging. Soybean oil was epoxidized using an eco-friendly method and used as a precursor for preparing the thermoset resin (ESOR). Different amounts of HNTs (0.25, 0.50, and 1.0 wt.%) were used to prepare the ESOR/HNTs blends. Various characteristics such as transparency, tensile strength, thermal resistance, and water absorption were investigated. While incorporating HNTs improved the tensile strength and thermal properties of the ESOR, it noticeably reduced its transparency at the 1.0 wt.% level. Therefore, HNTs were modified using sodium hydroxide and (3-Aminopropyl) triethoxysilane (APTES) and ESOR/HNTs blends were made using 1.0 wt.% of modified HNTs. It was shown that modifying HNTs using NaOH improved the transparency and mechanical properties of prepared blends compared to those with the same amount of unmodified HNTs. However, modifying using (3-Aminopropyl) triethoxysilane (APTES) decreased the transparency but improved the water absorption of prepared resins. This study provides valuable insights into the design of HNT-based ESOR blends as a sustainable material for medical packaging, contributing to the advancement of eco-friendly packaging solutions in the healthcare industry. [ABSTRACT FROM AUTHOR]

In this work, the incorporation of halloysite nanotubes (HNTs) and polyphenylene ether-grafted maleic anhydride copolymer (FB) into acrylonitrile butadiene styrene (ABS)/polyphenylene oxide (PPO) blend has been investigated to enhance the compatibility and performance of the blends. ABS/PPO blend (AP) with the weight ratio of ABS/PPO = 70/30 with 5 wt% loading of FB and different weight contents of HNTs were elaborated by melt blending process, and their properties were studied. The SEM observation revealed that AP blend exhibited dispersed phases of PPO droplets with apparent gaps between PPO and ABS phases, indicating poor adhesion between the polymers in the blend. As the compatibilizer, FB effectively enhanced the inter-phase interaction, minimizing the formation of interfacial gaps, evidenced by the SEM images, leading to the adhesion between ABS, PPO, and HNTs phases. As a result, the mechanical performance of the AP blend was significantly improved with the addition of FB and HNTs. At 5 wt% of HNT, the AP/FB/HNT blend exhibited the tensile strength of 37.47 MPa and flexural strength of 59.09 MPa compared to 26.60 MPa and 39.45 MPa of neat AP, respectively. The glass transition temperature of the modified blends showed shifts compared to the neat AP, which indicates the improvement in miscibility of the modified-AP blends. The thermal stability and flame resistance of the blends were also enhanced with the introduction of HNTs and FB, evidenced by the V-1 rating in the UL-94 test and the increase in limiting oxygen index (LOI). These results demonstrated that the incorporation of HNTs and FB is a promising and straightforward method to improve the properties of ABS/PPO blends. [ABSTRACT FROM AUTHOR]

To address the shortcomings of poor thermal stability, easy migration, and over‐plasticization of the liquid organic phosphorus flame retardant, cresyl diphenyl phosphate (CDP), we employed halloysite nanotube (HNT) as a carrier to load CDP, thus forming a novel composite (HNT‐CDP). The results demonstrated that the CDP loaded into HNT channels was 41 wt%. HNT‐CDP composites exhibited higher thermal stability, water resistance, and flame retardancy than mixtures of HNT and CDP in epoxy resin (EP). With a loading of 15 wt%, the limiting oxygen index of EP/HNT‐CDP increased to 48.3 and achieved a V‐0 rating in UL94 tests. Additionally, HNT‐CDP exhibited better inhibitory effects on the peak heat release rate and total heat release of EP, as well as a longer time to ignition, compared with the mixture. Moreover, as opposed to EP/HNT + CDP, EP/HNT‐CDP exhibited a significant 114.5% increase in tensile strength. These excellent thermal, water resistance, and mechanical properties can be primarily attributed to the loading of CDP by HNT channels. HNT effectively utilizes the channel confinement effect to isolate CDP from directly interacting with EP. The outstanding flame retardancy is mainly due to the synergistic effect between HNT and CDP after the formation of the composite. [ABSTRACT FROM AUTHOR]

Mine permitting requires an analysis of reasonably foreseeable impacts. In pit lake models, precipitates may be invoked to reduce dissolved aqueous concentrations, and thereby perceived groundwater impacts in the event of a throughflow pit lake after mine closure. The phases selected by modelers are generally based on geochemical theory rather than empirical data, and in this context, a review of available information is helpful. The mineralogy of Spanish, German, Czechian, Australian, and USA acidic pit lakes includes schwertmannite, jarosite, alunite, amorphous ferric oxyhydroxide (AFH), ferrihydrite, goethite, hydrobasaluminite, gibbsite, amorphous iron and aluminum oxyhydroxysulfates, gypsum, barite, and clays (kaolinite, dickite, halloysite, and smectite). Conversely, alkaline pit lakes exhibit distinct inorganic precipitation of calcite, ikaite, gaylussite, and siderite entraining metal removal from solutions at pH > 7 with biogenic iron oxyhydroxides and carbonates. Microbial activity facilitates the formation and transformation of metal sulfide precipitates predominantly in alkaline pit lakes but also in acidic water bodies. Therefore, predictive pit lake studies should focus on selecting authigenic precipitates on an empirical basis where possible, or if observed in corresponding environments in the case of permitting a new pit lake, taking into consideration kinetic barriers to mineral precipitation. This study characterized amorphous iron, aluminum, and calcium precipitate with entrained arsenic, manganese, and zinc floc from the previously acidic, now alkaline Lone Tree pit lake. The formerly acidic Liberty pit lake generated primarily gypsum and AFH, while the basic former Cortez pit lake sediment comprised calcite with solid solution Ba, Cd, Mg, Mn, and Zn. [ABSTRACT FROM AUTHOR]

Nanoclays (layered silicates) have been applied as effective reinforcements for polymeric matrices. Chitosan has gained much research interest owing to its remarkable physical features and applications. It is an important amino-polysaccharide formed from deacetylated chitin. The processability, properties, and applicability of chitosan have been enhanced in the form of nanoclay nanocomposites/hybrids. The ensuing high-performance chitosan/nanoclay nanocomposites have been observed in high-tech applications of engineering to biomedical fields. This state-of-the-art comprehensive overview debates the potential of chitosan/nanoclay nanocomposites. In this regard, numerous design combinations of the chitosan, modified chitosan, and chitosan blends have been observed with nanoclays (montmorillonite, bentonite, laponite, cloisite, halloysite nanoclay). Chitosan/nanoclay nanocomposites have been investigated for toxic ions/dyes/biological pollutants removal, flame retardancy, packaging, and antimicrobial/biomedical applications. Consequently, chitosan blends with laolinite nanoclay revealed thermal stability of 400–600 °C and around 80% degradation. Modified chitosan blends filled with organo-modified montmorillonite had non-flammability properties according to V-0 rating and a decrease in total peak heat release and heat release rate. Chitosan nanocomposites with montmorillonite or cloisite nanoclay have been tested for Pb2+, Cr6+, Cu 2+, Zn2+, etc. ions and adsorption capacity >100–300 mg/g was observed. Moreover, chitosan/montmorillonite nanocomposites had an adsorption capacity of 80–500 mg/g for methylene blue and rhodamin-6 dyes. For antimicrobial packaging application, chitosan/halloysite depicted antibacterial efficiency of > 80% against E. coli and S. aureus bacterial strains. Enhanced characteristics rely on chitosan-nanoclay interactions, interface formation, synergistic effects, and structure-property relationships. The future of these nanomaterials in the technical field depends on new designs, facile fabrication, and overcoming underlying challenges toward nanoclay nanomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] Peptide nucleic acid (PNA) is a DNA mimic that shows good stability against nucleases and proteases, forming strongly recognized complementary strands of DNA and RNA. However, due to its feeble ability to cross the cellular membrane, PNA activity and its targeting gene action is limited. Halloysite nanotubes (HNTs) are a natural and low-cost aluminosilicate clay. Because of their peculiar ability to cross cellular membrane, HNTs represent a valuable candidate for delivering genetic materials into cells. Herein, two differently charged 12-mer PNAs capable of recognizing as molecular target a 12-mer DNA molecule mimicking a purine-rich tract of neuroglobin were synthetized and loaded onto HNTs by electrostatic attraction interactions. After characterization, the kinetic release was also assessed in media mimicking physiological conditions. Resonance light scattering measurements assessed their ability to bind complementary single-stranded DNA. Furthermore, their intracellular delivery was assessed by confocal laser scanning microscopy on living MCF-7 cells incubated with fluorescence isothiocyanate (FITC)-PNA and HNTs labeled with a probe. The nanomaterials were found to cross cellular membrane and cell nuclei efficiently. Finally, it is worth mentioning that the HNTs/PNA can reduce the level of neuroglobin gene expression, as shown by reverse transcription-quantitative polymerase chain reaction and western blotting analysis. [ABSTRACT FROM AUTHOR]

The utilization of natural clay minerals for synthesizing nano-sized metal-organic frameworks (MOFs) supported materials offers great advantages for rational design of innovative catalysts, which promotes the low-cost and large-scale environmental remediation applications. This work reported a facile and scalable encapsulation-pyrolysis strategy to prepare novel Au-HNTs@Co-NC core-shell catalyst for catalytic reduction of nitroaromatic pollutants. The HNTs were modified with aminosilane on the external surface for effectively anchoring well-dispersed and ultrasmall Au NPs. Uniform nano-sized ZIF-67 crystals controllably embraced the Au-HNTs via in-situ growth induced by electrostatic adsorption. The N 2 atmosphere pyrolysis at 550 °C resulted in Co NPs embedded into N-doped carbon substrates, and transformed ZIF-67 crystals into Co-NC layers for preferable encapsulation and stabilization of Au NPs. The as-prepared Au-HNTs@Co-NC-550 catalyst manifested splendid catalytic performance for p-nitrophenol reduction, and achieved the reaction rate constant and TOF value estimated as 2.025 min−1 and 49.25 min−1, which significantly exceeded the behaviors of as-prepared control materials. Moreover, the catalyst also displayed excellent catalytic capability toward the reduction of nitroanilines and homologues and isomers of p-nitrophenol, indicative of its decent general applicability. After 8 cycles of reactions, the catalyst still retained brilliant reusability and structural stability with good magnetic property for expedient separation. The advantageous hollow core-shell structure combining HNTs and ZIF-67 derivatives enhanced the reactant diffusion and transfer. The N doping and electronegativity difference between Co and Au aroused higher electron uptake and facilitated electron transport during the reduction process. Meanwhile, the Co–H and Au–H bonds formed the strong synergistic effect for superior cooperative catalytic performance of the catalyst. [ABSTRACT FROM AUTHOR]

The present work characterized pure halloysite clay mineral nanotubes (HNT) and their composites with silver nanoparticles (AgNPs) as ionizing radiation dosimeters using the optically stimulated luminescence (OSL) phenomena. We also explored the HNT’s capacity to scavenge heavy metals from solutions to incorporate silver ions in its structure and produce silver nanoparticles in the HNTs, aiming to increase the HNT’s OSL intensity. Reflectance spectra in the UV-visible region, X-ray diffraction, and transmission electron microscopy were performed to confirm the formation of AgNPs attached to the nanotubes. Furthermore, the OSL signals revealed an enhanced OSL intensity in samples containing AgNPs, possibly associated with the silver nanostructures’ plasmonic properties. Therefore, HNTs and their composites are alternative materials for applications in OSL dosimetry. [ABSTRACT FROM AUTHOR]

Post-recycling sodium polyacrylate (SPA) derived from the selective recycling of personal hygiene products was tested as a potential key component of soil modifiers. Recycled SPA in combination with layered aluminosilicate (halloysite) with the sorption capacity of fertilizers allows for the creation of a fully functional, original system responsible for both water retention in soil and controlled dosing of fertilizers. The use of post-recycling SPA (possibly partially supplemented with virgin SPA) is advantageous for the natural environment. The results of different water types retention in post-recycling SPA (deionized water, rainwater, tap water) are discussed. The most beneficial effects of R-SPA swelling and water accumulation are achieved when it comes into contact with rainwater. The clear impact of Mg2+ ions on the sorption capacity of R-SPA introduces the need for a technological compromise between the solution composition (N, P, K or N, P, K, Mg) affecting its fertilization value and the possibility of obtaining maximum R-SPA swelling. The sorption capacity of R-SPA can be slightly increased by using R-SPA/V-SPA mixtures, but R-SPA still plays a decisive role in this system. The possibility of technological adjustment of the leaching rate of fertilizer components under dynamic conditions using different combinations of (R-SPA/V-SPA)/HAL was demonstrated by column tests. [ABSTRACT FROM AUTHOR]

This study explores the use of Halloysite NanoTubes (HNTs) as photocatalysts capable of decomposing organic dyes under exposure to visible or ultraviolet light. Through a systematic series of photocatalytic experiments, we unveil that the photodegradation of Rhodamine B, used as a model cationic dye, is significantly accelerated in the presence of HNTs. We observe that the extent of RhB photocatalytic degradation in 100 min in the presence of the HNTs is ~four times higher compared to that of bare RhB. Moreover, under optimized conditions, the as-extracted photodegradation rate of RhB (~0.0022 min−1) is comparable to that of the previously reported work on the photodegradation of RhB in the presence of tubular nanostructures. A parallel effect is observed for anionic Coumarin photodegradation, albeit less efficiently. Our analysis attributes this discrepancy to the distinct charge states of the two dyes, influencing their attachment sites on HNTs. Cationic Rhodamine B molecules preferentially attach to the outer surface of HNTs, while anionic Coumarin molecules tend to attach to the inner surface. By leveraging the unique properties of HNTs, a family of naturally occurring nanotube structures, this research offers valuable insights for optimizing photocatalytic systems in the pursuit of effective and eco-friendly solutions for environmental remediation. [ABSTRACT FROM AUTHOR]

This study explores the impact of incorporating Halloysite Nanotubes (HNTs) nanoparticles on the low-velocity impact (LVI) behavior of carbon fiber (CF) laminate epoxy nanocomposites. The objective of this investigation was to observe the effects of different nanotube loadings (0.5 wt.% and 0.7 wt.%) on CF composites and assess their impact resistance. To achieve this, the CF was subjected to Electrophoretic Deposition (EPD) process to introduce the HNTs. Vacuum-assisted Resin Transfer Molding (VaRTM) was employed to fabricate the CF-reinforced epoxy-based laminated nanocomposites with incorporated HNTs. LVI tests were conducted following the ASTM-D-7136 standard, utilizing impact energies of 10 J and 15 J. Subsequently, the damaged areas within the composites were examined using optical microscopy (OM) and scanning electron microscope (SEM). The findings of this investigation revealed a significant enhancement in impact damage resistance with the addition of HNTs. The highest damage resistance and minimal energy absorption were observed at a loading of 0.7 wt.% HNTs. The results reveal that incorporating 0.7 wt.% HNTs substantially reduces delamination damage, influenced by absorbed impact energy. As well it composite underscores enhanced interlaminar bonding through 0.5 wt.% and 0.7 wt.% HNTs modification. Hence, we confidently assert that the addition of HNTs nanoparticles to CF/epoxy composites has considerably influenced the impact response of the nanocomposites. [ABSTRACT FROM AUTHOR]