Reparation of recycled acrylonitrile- butadiene-styrene by pyromellitic dianhydride: Reparation performance evaluation and property analysis

Review and Assessment of Existing and Future Techniques for Traceability with Particular Focus on Applicability to ABS Plastics

It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition to a circular economy and help to overcome obstacles. In the near future, traceability and information exchange between all actors in the value chain of the plastics industry will be crucial to establishing more effective recycling systems. Recycling plastics is a complex process that is particularly complicated in the case of acrylonitrile butadiene styrene (ABS) plastic because of its versatility and use in many applications. This literature study is part of a larger EU-funded project with the acronym ABSolEU (Paving the way for an ABS recycling revolution in the EU). One of its goals is to propose a suitable traceability system for ABS products through physical marking with a digital connection to a suitable data-management system to facilitate the circular use of ABS. The aim of this paper is therefore to review and assess the current and future techniques for traceability with a particular focus on their use for ABS plastics as a basis for this proposal. The scientific literature and initiatives are discussed within three technological areas, viz., labelling and traceability systems currently in use, digital data sharing systems and physical marking. The first section includes some examples of systems used commonly today. For data sharing, three digital technologies are discussed, viz., Digital Product Passports, blockchain solutions and certification systems, which identify a product through information that is attached to it and store, share and analyse data throughout the product's life cycle. Finally, several different methods for physical marking are described and evaluated, including different labels on a product's surface and the addition of a specific material to a polymer matrix that can be identified at any point in time with the use of a special light source or device. The conclusion from this study is that the most promising data management technology for the near future is blockchain technology, which could be shared by all ABS products. Regarding physical marking, producers must evaluate different options for individual products, using the most appropriate and economical technology for each specific product. It is also important to evaluate what information should be attached to a specific product to meet the needs of all actors in the value chain.

Adsorbents obtained from recycled polymeric materials for retention of different pollutants: A review

Polymeric waste is an environmental problem, with an annual world production of approximately 368 million metric tons, and increasing every year. Therefore, different strategies for polymer waste treatment have been developed, and the most common are (1) redesign, (2) reusing and (3) recycling. The latter strategy represents a useful option to generate new materials. This work reviews the emerging trends in the development of adsorbent materials obtained from polymer wastes. Adsorbents are used in filtration systems or in extraction techniques for the removal of contaminants such as heavy metals, dyes, polycyclic aromatic hydrocarbons and other organic compounds from air, biological and water samples. The methods used to obtain different adsorbents are detailed, as well as the interaction mechanisms with the compounds of interest (contaminants). The adsorbents obtained are an alternative to recycle polymeric and they are competitive with other materials applied in the removal and extraction of contaminants.

Simulating and Predicting the Part Warping in Fused Deposition Modeling by Thermal-Structural Coupling Analysis

As the most commonly used additive manufacturing technology, fused deposition modeling (FDM) still faces some technical issues caused by temperature change-induced unsteady thermal stress and warping. These issues can further lead to the deformation of printed parts and even terminate the printing process. In response to these issues, this article established a numerical model of temperature field and thermal stress field for FDM by finite element modeling and "birth-death element" technique to predict the deformation of the part. What makes sense in this process is that the logic of elements sort based on ANSYS Parametric Design Language (APDL) was proposed to sort the meshed elements, which was aimed to perform FDM simulation quickly on the model. In this work, the effects of the sheets shape and infill line directions (ILDs) on the distortion during FDM were simulated and verified. From the analysis of stress field and deformation nephogram, the simulation results indicated that ILD had greater effects on the distortion. Moreover, the sheet warping became most serious when the ILD was aligned with the diagonal of the sheet. The simulation results matched well with the experimental results. Thus, the proposed method in this work can be used to optimize the printing parameters for FDM process.

3D-MID Technology for Surface Modification of Polymer-Based Composites: A Comprehensive Review

The three-dimensional molded interconnected device (3D-MID) has received considerable attention because of the growing demand for greater functionality and miniaturization of electronic parts. Polymer based composite are the primary choice to be used as substrate. These materials enable flexibility in production from macro to micro-MID products, high fracture toughness when subjected to mechanical loading, and they are lightweight. This survey proposes a detailed review of different types of 3D-MID modules, also presents the requirement criteria for manufacture a polymer substrate and the main surface modification techniques used to enhance the polymer substrate. The findings presented here allow to fundamentally understand the concept of 3D-MID, which can be used to manufacture a novel polymer composite substrate.

Challenges and opportunities of solvent-based additive extraction methods for plastic recycling

Additives are ubiquitously used in plastics to improve their functionality. However, they are not always desirable in their 'second life' and are a major bottleneck for chemical recycling. Although research on extraction techniques for efficient removal of additives is increasing, it resembles much like uncharted territory due to the broad variety of additives, plastics and removal techniques. Today solvent-based additive extraction techniques, solid-liquid extraction and dissolution-precipitation, are considered to be the most promising techniques to remove additives. This review focuses on the assessment of these techniques by making a link between literature and physicochemical principles such as diffusion and Hansen solubility theory. From a technical point of view, dissolution-precipitation is preferred to remove a broad spectrum of additives because diffusion limitations affect the solid-liquid extraction recoveries. Novel techniques such as accelerated solvent extraction (ASE) are promising for finding the balance between these two processes. Because of limited studies on the economic and environmental feasibility of extraction methods, this review also includes a basic economic and environmental assessment of two extreme cases for the extraction of additives. According to this assessment, the feasibility of additives removal depends strongly on the type of additive and plastic and also on the extraction conditions. In the best-case scenario at least 70% of solvent recovery is required to extract plasticizers from polyvinyl chloride (PVC) via dissolution-precipitation with tetrahydrofuran (THF), while solid-liquid extraction of phenolic antioxidants and a fatty acid amide slip agents from polypropylene (PP) with dichloromethane (DCM) can be economically viable even without intensive solvent recovery.

Microplastic pollution in water and fish samples around Nanxun Reef in Nansha Islands, South China Sea

Nanxun Reef is one of the typical reefs in Nansha Islands, South China Sea. As the Nansha Islands are surrounded by certain developing countries, the economic and population growth have resulted in increased surface runoff of persistent organic pollutants in offshore areas. Microplastic has been found in many freshwaters and sea areas in recent years. However, the levels of microplastics contamination in Nansha Islands are still uncharted. In this study, 15 water and 35 fish samples were collected around the Nanxun Reef. The average concentration of microplastics was 1733 items/m³ for surface water samples and 3.1 items per individual for fish samples. The majority of ingested microplastics by fish were fibers, mostly transparent or blue. In surface water samples, blue microbeads were the main types of microplastics, accounting for 76.5% of all the detected particles. The main size of microplastics was <0.5 mm both in water and fish samples. Our results demonstrated that fishery activities and human domestic sewage might be the dominant sources of microplastic pollution in the Nansha Island, South China Sea.

The synthesis of nanofiber membranes from acrylonitrile butadiene styrene (ABS) waste using electrospinning for use as air filtration media

Acrylonitrile butadiene styrene (ABS) waste has been successfully recycled into nanofiber membranes by an electrospinning method for air filter applications. The ABS precursor solutions were made by dissolving the ABS waste in three different solvents, DMAc, DMF, and THF, with various concentrations of 10, 20, and 30 wt%. The solvent and solution concentrations affected the fiber properties (size and morphology) and membrane properties (wettability, crystallinity, and mechanical). Accordingly, we tested the fabricated membranes using SEM, FTIR, XRD, water contact angle, and tensile strength test measurements. The SEM images depicted three different morphologies, i.e. beads, beaded fibers, and pure fibers. The FTIR spectra showed that the solvents completely evaporated during the electrospinning process. The water contact angle test exhibited the hydrophobic properties of all the membrane samples. The XRD spectra showed the amorphous structures of all the membranes. The tensile strength test showed that the membranes fabricated using DMF and DMAc solvents had the best mechanical properties. Considering the fiber size, wettability, and mechanical properties, the membranes fabricated using DMAc and DMF solvents had the best criteria as air filter media. Filtration tests on the membranes fabricated using DMAc and DMF solvents with various solution concentrations depicted that the beads affected the membrane pressure drop and efficiency. The beads gave more space among the fibers, which facilitated the air flow through the membrane. The beads greatly reduced the pressure drop without an overly reduced membrane filtration efficiency. This led to a high-quality factor of the membranes that demonstrated their applicability as potential air filter media.

Blends of rABS and SEBS: Influence of In-Situ Compatibilization on the Mechanical Properties

In this study, the in-situ compatibilization reaction between recycled acrylonitrile–butadiene–styrene copolymer (rABS) and functional styrene–ethylene–butylene–styrene block maleic anhydride (SEBS-g-MAH) was confirmed, which contributed to the toughening phenomenon of rABS, especially the notched impact strength. As mechanical test that manifested, the rABS/SEBS-g-MAH blends are stronger and more ductile than the rABS/SEBS blends. Prominently, the former has great advantage over the latter in terms of improving the impact performance. Scanning electron microscope (SEM) images showed that the compatible segments that were generated by reaction not only improve the interface adhesion of rABS/SEBS-g-MAH blends but also promote the evolution of co-continuous structures, which can be evidently observed after etching. Furthermore, the SEM micrographs of tensile fracture surfaces indicated that the formation of the co-continuous phase and the improvement of interface adhesion are the most profound reasons for the excellent tensile properties of the rABS/SEBS-g-MAH blends. The impact fracture surface revealed that two-phase interface affects crack propagation and shear yielding absorbs more impact energy than simple interface debonding does at higher deformation rates. Meanwhile, rheological analysis demonstrated that the complex viscosity of the rABS/SEBS-g-MAH (80/20 wt%) blend with a co-continuous structure exhibits a maximum positive deviation at low frequencies from the theoretical value calculated using the rule of logarithmic sum, which indicated a connection between co-continuous structure and complex viscosity. In addition, the storage modulus vs. loss modulus curves of the blends revealed that the viscoelastic behavior of rABS/SEBS-g-MAH blends is very similar to that of rABS.

Past and emerging topics related to electronic waste management: top countries, trends, and perspectives

A bibliometric analysis was performed to assess historical and recent research trends regarding e-waste studies from 1998 to 2018. Documents related to e-waste were identified from the Clarivate Analytics Web of Science© (WoS) database, and a total of 3311 academic articles was retrieved. The analysis was performed from four main aspects: (1) publication activity by year, by WoS category, and by geographic distribution; (2) journals; (3) most-cited papers; and (4) top 10 countries and author keyword analysis. The number of publications concerning e-waste issues has increased substantially over the last 20 years, especially in the environmental science category, and more than a third of the publications were produced in China (1181 records). Waste Management and Environmental Science & Technology were the most sought-after journals for disseminating the results. Studies related to "e-waste flow analysis," "recycling," "recovery of precious metals," and "risk assessment of recycling areas" have been the most common for several years. The analysis of keywords suggested that there are many topics on electronic waste and that each country has presented a different focus of research. Overall, the bibliometric analysis proved to be an efficient tool with which to monitor historical and current research trends and to evaluate the sheer volume of currently existing scientific literature on e-waste topics.

Novel low-cost carboxymethyl cellulose microspheres with excellent fertilizer absorbency and release behavior for saline-alkali soil

Saline-alkali soil and fertilizer loss severely restrict agriculture on the Songnen Plain in China. To resolve this problem, carboxymethyl cellulose immobilized slow-release fertilizer microspheres (CFM) with homogeneity pore structure, high porosity, biodegradable biological macromolecules and excellent fertilizer absorbency were synthesized by the combination of inverse emulsion polymerization and microfluidic method. By optimizing the synthesis conditions, the water absorption of CFM reached 8725 g g^-1 in deionized water. The absorbency behaviors of CFM were highly sensitive to pH, ionic strength, and ionic species. In 5 g L^-1 urea solution, the adsorption capacity of CFM was 3342.84 g g^-1. The CFM showed excellent urea retention at 80 °C for 5 h and sustained release performance in soil. Besides, degradation rate of CFM was closed to 98.2% in Aspergillus niger at the third day. CFM had the advantages of high pH sensitivity, salt resistance, and good fertilizer absorbency and retention. Therefore, it will be prospecting fertilizer sustained release agent in agriculture.

Mechanical properties and long-term durability of recycled polysulfone plastic

In view of the recycling of PSU plastics has a good energy saving and environmental protection significance. This paper is concerned with the mechanical properties, and long-term durability of virgin and recycled polysulfone plastics (PSU) collected from wasted PSU nonwovens, the mechanical experiment of tensile test and Izod impact test are carried out to investigate the effect of cycle processing on the performance of PSU. The long-term durability of virgin and recycled PSU is studied base on time-temperature superposition by using a dynamic mechanical analysis (DMA). The thermal stability is evaluated by pyrolytic activation energy calculated by Iso-conversional kinetics method using a Thermogravimetric analysis (TGA). The results show that the recycled PSU exhibits the similar tensile property while lower impact strength than virgin PSU. The long-term durability and thermal stability of virgin PSU are better than recycled PSU and decreased with increasing the times of cycle processing, which is attributed to the mixing of impurities and degradation of the molecular structure in the recycling process.

Phenol adsorption and desorption with physically and chemically tailored porous polymers: Mechanistic variability associated with hyper-cross-linking and amination

Understanding phenol adsorption-desorption mechanisms allows adsorbent tailoring to improve capacity and adsorbent reuse. Amberlite™ XAD4, a commercial styrenic polymer that is convenient to physically and chemically modify, was functionalized with dimethylamine (DMA) or trimethylamine (TMA) and/or hyper-cross-linked with 1,2-dichloroethane. These modifications were applied to enhance individual and/or synergistic phenol adsorption mechanisms, including hydrogen bonding, electrostatic interactions, and π-π dispersion forces. While XAD4-DMA adsorbs more phenol at pH = 6, XAD4-TMA has 23% higher capacity at pH = 11 due to adsorbate deprotonation that increases electrostatic interactions. Combining hyper-cross-linking with amination maximizes adsorption capacity due to synergistic impacts associated with increased micropore volume and surface affinity. Amine groups reduce desorption efficiency by 6-94% due to stronger adsorbate-adsorbent interactions compared to π-π dispersion forces. Isobutanol, which forms hydrogen bonds, is the most efficient desorption solvent, followed by chloroform, which has the same polarity index but does not hydrogen bond. n-Hexane only desorbs phenol removed with π-π dispersion forces and is not appropriate to regenerate aminated polymers. 0.1 N NaOH is an environmentally benign solvent for regenerating as-received XAD4 and XAD4-DMA, but not XAD4-TMA. Understanding phenol adsorption mechanisms allows development of physiochemically modified polymers with increased phenol adsorption capacity and regeneration efficiency.

Effects of a Phosphorus Flame Retardant System on the Mechanical and Fire Behavior of Microcellular ABS

The present work deals with the study of phosphorus flame retardant microcellular acrylonitrile–butadiene–styrene (ABS) parts and the effects of weight reduction on the fire and mechanical performance. Phosphorus-based flame retardant additives (PFR), aluminum diethylphosphinate and ammonium polyphosphate, were used as a more environmentally friendly alternative to halogenated flame retardants. A 25 wt % of such PFR system was added to the polymer using a co-rotating twin-screw extruder. Subsequently, microcellular parts with 10, 15, and 20% of nominal weight reduction were prepared using a MuCell^® injection-molding process. The results indicate that the presence of PFR particles increased the storage modulus and decreased the impact energy determined by means of dynamic-mechanical-thermal analysis and falling weight impact tests respectively. Nevertheless, the reduction of impact energy was found to be lower in ABS/PFR samples than in neat ABS with increasing weight reduction. This effect was attributed to the lower cell sizes and higher cell densities of the microcellular core of ABS/PFR parts. All ABS/PFR foams showed a self-extinguishing behavior under UL-94 burning vertical tests, independently of the weight reduction. Gradual decreases of the second peak of heat release rate and time of combustion with similar intumescent effect were observed with increasing weight reduction under cone calorimeter tests.

Low-Temperature Cross-Linkable Small Molecules for Fully Solution-Processed OLEDs

Cross-linkable hole-transporting, host, and electron-transporting materials with a new cross-linking group, uracil, are designed and synthesized. These compounds exhibited good solubility in common organic solvents and excellent solvent resistance after cross-linking at a low temperature of 120 °C. The OLED was fabricated by all-solution processing using cross-linkable synthetic compounds, except for the electrodes. This device exhibited a current efficiency of 39.2 cd A^-1 and a power efficiency of 15.3 lm W^-1 .

Synthesis and evaluation of water soluble pH sensitive poly (vinyl alcohol)-doxorubicin conjugates

The accuracy of spatiotemporal control cargo delivery and release are primordial to enhance the therapeutic efficiency and decrease the undesirable effects, in this context a novel prodrug were developed based on biocompatible polyvinyl alcohol (PVA) substrate. PVA was conjugated to doxorubicin (PVA-DOX) via an acid-labile hydrazone linkage. PVA was first functionalized with acidic groups, then reacted with hydrazine hydrate to form an amide bond. The amine group of PVA hydrazide was linked to carbonyl group (C = O) of DOX to form a pH sensitive hydrazone bond. The molecular structure of the PVA-DOX was confirmed by FTIR, XPS, and ¹H-NMR analysis methods. The degree of grafting were evaluated by TGA and confirmed by XPS, which reveals the successful bond attachment of DOX to PVA. Our findings confirm pH dependent DOX release from PVA-DOX prodrug with faster release rate in acidic environment (pH 5.0, pH 6.0) and slower release rate in neutral pH environment (pH 7.4). Compared to the primary DOX, our synthesized PVA-DOX conjugates could exhibit a promising therapeutic effect, high biocompatibility and zero premature release. The results prove the successful synthesis of PVA-DOX conjugates with high efficiency.

Sol-gel derived flexible silica aerogel as selective adsorbent for water decontamination from crude oil

Oil spills are the most important threat to the sea ecosystem. The present study is an attempt to investigate the effects of sol-gel parameters on seawater decontamination from crude oil by use of flexible silica aerogel. To this goal, methyltrimethoxysilane (MTMS) based silica aerogels were prepared by two-step acid-base catalyzed sol-gel process, involving ambient pressure drying (APD) method. To investigate the effects of sol-gel parameters, the aerogels were prepared under two different acidic and basic pH values (i.e. 4 and 8) and varied ethanol/MTMS molar ratios from 5 to 15. The adsorption capacity of the prepared aerogels was evaluated for two heavy and light commercial crude oils under multiple adsorption-desorption cycles. To reduce process time, desorption cycles were carried out by using roll milling for the first time. At optimum condition, silica aerogels are able to uptake heavy and light crude oils with the order of 16.7 and 13.7, respectively.

Mechanical Measurement System and Precision Analysis for Tactile Property Evaluation of Porous Polymeric Materials

Tactile properties are one of the most important attributes of porous polymeric materials such as textiles, comprising a subjective evaluation index for textile materials and functional clothing, primarily affecting the sensation of comfort during the wearing of a garment. A new test method was proposed, and a mechanical measurement system was developed to objectively characterize the tactile properties of porous polymeric materials by simulating the dynamic contact processes during human skin contact with the materials and in consideration of different aspects of tactile sensations. The measurement system can measure the bending, compression, friction, and thermal transfer properties in one apparatus, and is capable of associating the objective measurements with the subjective tactile sensations. The test and evaluation method, the components of the mechanical measurement system, the definition and grading method of the evaluation indices, and the neural network prediction model from objective test results to subjective sensations of tactile properties were presented. The experiments were conducted for the objective tests and correlation tests. Seven types of porous polymeric sheet materials from seven categories for the tactile properties were cut to a size of 200 mm × 200 mm and tested. Each index of tactile properties was significantly different (P < 0.05) between different sheet materials. The correlations of bending, compression, friction, and thermal transfer properties with Kawabata KES test methods were analyzed. An intra-laboratory test was conducted and an analysis of the variance was performed to determine the critical differences of within laboratory precisions of the measurement system. This mechanical measurement system provides a method and system for objective measurement and evaluation of tactile properties of porous polymeric sheet materials in industrial application.

Self-regulation in chemical and bio-engineering materials for intelligent systems

Herein, the authors review the self-regulation system secured by well-designed hybrid materials, composites, and complex system. As a broad concept, the self-regulated material/system has been defined in a wide research field and proven to be of great interest for use in a biomedical system, mechanical system, physical system, as the fact of something such as an organisation regulating itself without intervention from external perturbation. Here, they focus on the most recent discoveries of self-regulation phenomenon and progress in utilising the self-regulation design. This paper concludes by examining various practical applications of the remarkable materials and systems including manipulation of the oil/water interface, cell out-layer structure, radical activity, electron energy level, and mechanical structure of nanomaterials. From material science to bioengineering, self-regulation proves to be not only viable, but increasingly useful in many applications. As part of intelligent engineering, self-regulatory materials are expected to be more used as integrated intelligent components.

The stiffness-thermal conduction relationship at the composite interface: the effect of particle alignment on the long-range confinement of polymer chains monitored by scanning thermal microscopy

The polymer/filler interface is usually considered as a thermal barrier in composites due to the mismatch of the phonon frequency across the interface. How the interface plays its role in thermal conduction has not yet been fully understood. In this work, scanning thermal microscopy is used to map the probe current across the composite interface and force-displacement curves are obtained to assess the polymer stiffness. The microscale stiffness-thermal conduction relationship is investigated at the composite interface in three representative cases: a single aggregated particle domain, two neighboring particle domains and two parallelly aligned particle chains. In the studied poly(vinyl alcohol) (PVA)/Fe₃O₄ composites, it is revealed that the interface property dominates the thermal conduction behavior rather than particle percolation. The long range order of polymer chains surrounding the particle domains is responsible for the enhanced crystallinity and thermal conductivity of the composites. With magnetic alignment of Fe₃O₄ particles, PVA crystallinity and thermal conductivity can be further enhanced. The macroscopic thermal conductivity measurement is highly consistent with the microscale observation. Specifically, with only 2.3 vol% loading of Fe₃O₄ in PVA, the thermal conductivity can be increased by 56% to 0.42 W m^-1 K^-1. By the magnetic alignment of the particles at the same loading, 133% enhancement of thermal conductivity (∼0.63 W m^-1 K^-1) can be achieved. This work presents an experimental study on the exploration of the interface property-thermal conductivity relationship in differently structured micro-domains and reveals the positive role of the composite interface in thermal conduction.

Comparative Evaluation of Biological Performance, Biosecurity, and Availability of Cellulose-Based Absorbable Hemostats

Hemorrhage remains a leading cause of death after trauma, and developing a hemostat with excellent performance and good biosecurity is an extremely active area of research and commercial product development. Although oxidized regenerated cellulose (ORC) has been developed to address these problems, it is not always efficient and its biosecurity is not perfect. We aimed to refine ORC via a simple and mild neutralization method. The prepared neutralized oxidized regenerated cellulose (NORC) showed a superior gel property due to its chemical structure. The biological performance of both ORC and NORC was systematically evaluated; the results showed that ORC would induce erythema and edema in the irritation test, whereas NORC did not cause any adverse inflammation, indicating NORC had desirable biocompatibility. We further demonstrated that NORC confirmed to the toxicity requirements of International Organization for Standardization (ISO) standards; however, ORC showed an unacceptable cytotoxicity. The rabbit hepatic defect model stated that NORC exhibited better ability of hemostasis, which was attributed to its significant gel performance in physiological environment.

Preparation of polypropylene/Mg-Al layered double hydroxides nanocomposites through wet pan-milling: non-isothermal crystallization behaviour

Differential scanning calorimeter was used to extensively investigate the non-isothermal crystallization of polypropylene (PP)/layered double hydroxides (LDHs) nanocomposites prepared through wet solid-state shear milling. The corresponding crystallization kinetics was further investigated by using Ozawa, modified Avrami and combined Avrami-Ozawa method, respectively. The results showed that the Ozawa method could not well describe the crystallization kinetics of pure PP and its nanocomposites. Comparatively, the modified Avrami method as well as the combined Avrami-Ozawa method gives the satisfactory results. Under the effect of pan-milling, the produced LDH nano intercalated/exfoliated particles exhibit the inhibitive effect on the PP nucleation but more remarkable promotion effect on the spherulite growth, leading to enhancement in the overall crystallization rate. This is reflected in increase of the calculated fold surface free energy σ_e and also the supercooling degree ΔT required for crystallization nucleation. In addition, the polarized optical microscopy observation also verifies the higher spherulite growth rate of PP/LDHs nanocomposites than that of pure PP.

Synthesis, characterization and photocatalytic activity of mixed-metal oxides derived from NiCoFe ternary layered double hydroxides

Ternary NiCoFe mixed-metal oxides have demonstrated higher photoelectrocatalytic activity in degrading methylene blue (MB).

Homogenous Dispersion of MoS2 Nanosheets in Polyindole Matrix at Air-Water Interface Assisted by Langmuir Technique

Two-dimensional (2D) inorganic layered materials when embedded in organic polymer matrix exhibit exotic properties that are grabbing contemporary attention for various applications. Here, nanosheet morphology of molybdenum disufide (MoS₂) synthesized via one-pot facile hydrothermal reaction are exfoliated in benign aqueous medium in the presence of indole to obtain a stable dispersion. These exfoliated nanosheets then act as host to template the controlled polymerization of indole. The preassembled MoS₂-polyindole (MoS₂-PIn) nanostructures are reorganized at the air-water interface using the Langmuir method to facilitate maximum interfacial interaction between nanosheet and polymer. This report emphasizes large area, homogeneous dispersion of uniform-sized MoS₂ nanosheets (40-60 nm diameter) in the PIn matrix and the formation of stable and uniform film via the Langmuir-Schaefer (LS) method. These self-assembled, MoS₂ decorated PIn LS films are characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The fabricated LS films in sandwiched structure Al/MoS₂-PIn/ITO as the Schottky diode portrayed remarkable enhancements in charge transport properties. Our study illustrates the potential of the MoS₂-PIn LS film in electronic applications and opens a new dimension for uniform dispersion of 2D materials in other polymers via the Langmuir method for device fabrication and enhancement of electrical properties.

Bioinspired, Graphene/Al2O3 Doubly Reinforced Aluminum Composites with High Strength and Toughness

Nacre, commonly referred to as nature's armor, has served as a blueprint for engineering stronger and tougher bioinspired materials. Nature organizes a brick-and-mortar-like architecture in nacre, with hard bricks of aragonite sandwiched with soft biopolymer layers. However, cloning nacre's entire reinforcing mechanisms in engineered materials remains a challenge. In this study, we employed hybrid graphene/Al₂O₃ platelets with surface nanointerlocks as hard bricks for primary load bearer and mechanical interlocking, along with aluminum laminates as soft mortar for load distribution and energy dissipation, to replicate nacre's architecture and reinforcing effects in aluminum composites. Compared with aluminum, the bioinspired, graphene/Al₂O₃ doubly reinforced aluminum composite demonstrated an exceptional, joint improvement in hardness (210%), strength (223%), stiffness (78%), and toughness (30%), which are even superior over nacre. This design strategy and model material system should guide the synthesis of bioinspired materials to achieve exceptionally high strength and toughness.