Advanced Nanocomposite Materials Research Articles

Frontal Polymerization for the Rapid Obtainment of Polymer Composites.

Among the different polymerization techniques, frontal polymerization (FP) has gained high interest from the scientific community because of its peculiar characteristics: in particular, compared to classic polymerization reactions, FP allows for a better exploitation of the heat of polymerization involved, without requiring any external energy input apart from an initial photo or thermal ignition that triggers the reaction. The latter usually propagates in a few tenths of seconds or (at most) minutes through a hot self-sustaining polymerization front, giving rise to the formation of fully cured thermosetting networks or thermoplastic polymers. Furthermore, different polymerization mechanisms can be involved in FP reactions, comprising cationic or anionic, ring-opening metathesis, and free-radical polymerization, among others. Further, it is possible to run FP reactions in bulk, in solution, or even using solid monomers if they are melted at the temperature of the front, notwithstanding the possibility of using reactive systems containing fillers or fiber/fabric reinforcements. In this context, the use of FP is becoming very important also for the design and production of advanced (nano)composite materials, saving processing time and achieving the completeness of the curing reaction, even in the presence of high filler/reinforcement loadings. Therefore, this mini-review aims to provide the reader with the basics of FP and its main peculiarities, even in the context of preparing high-performing composites. In this respect, some recent case studies witnessing the potentialities of frontal polymerization for the design of advanced (nano)composite systems will be elucidated. Finally, some perspectives about possible future developments will be proposed.

Emerging trends of ferrite-based nanomaterials as photocatalysts for environmental remediation: A review and synthetic perspective

Efficient wastewater treatment processes are in high demand for removing organic and inorganic pollutants. Photocatalysis, as an environmentally friendly technology, has shown significant progress in the treatment of contaminated wastewater. This review explores the potential of spinel ferrite-based nanomaterials as efficient photocatalysts for wastewater treatment. To enhance their properties, ferrites have been combined with advanced materials, such as BiOX, MXene, and g-C3N4 to form binary and ternary nanocomposites. We highlight the state-of-the-art in these binary and ternary spinel ferrite nanocomposites in the photocatalytic degradation of organic pollutants. These ferrite nanocomposites showed superior photocatalytic performance due to enhanced properties such as increasing the capacity for light utilization, slowing electron-hole recombination, and reducing agglomeration. Furthermore, our review explores recent research on template-assisted synthesis, a novel approach for fine-tuning the morphology of spinel ferrites and enhancing their catalytic efficiency. The impact of both the soft and hard templates on the properties of the produced ferrite nanomaterials is discussed. Overall, this unique combination of advanced nanocomposite materials and structural control using template-assisted approaches paves the way for a new generation of highly efficient photocatalysts. Thus, we provide a comprehensive overview of recent advances in the development of ferrite nanocomposites, underlining their potential as photocatalysts for environmental remediation applications.

High-performance cellulose nanofibers-based actuators with multi-stimulus responses and energy storage

Smart actuating materials have received tremendous attention due to their promising applications in miniaturized robots, integrated electronics and wearable devices. However, simultaneously achieving sensitive multi-stimuli responsiveness, preferable energy storage capability and adequate mechanical properties by one material in a simple yet efficient way remains a considerable challenge. Herein, we propose a novel multi-responsive nanocomposite film actuator consisting of negatively charged cellulose nanofibers (CNF), polydopamine-chelated MXene-Fe3O4 nanohybrids (PMF) and positively charged carbon nanotubes (CCNT) via a cost-efficient electrostatic self-assembly approach. Benefiting from the laminated porous structure and compositional superiorities, including the water-induced swelling effect of CNF and PMF, conductive CCNT with countless interior hydrophobic channels and magneto-conductive properties of PMF, the optimized nanocomposite film actuator presents a high bending speed (100.5°/s), ultrashort actuation time (2.0 s), long-term stability (1005 cycles) and good magnetic response. These actuators can be assembled into a supercapacitor exhibiting an areal capacitance of 33.5 mF/cm2 at 0.5 mA/cm2 and good cycling stability with a capacitance retention of 80.5 % after 5000 cycles. Furthermore, the actuators are designed as soft robots with different motion modes, mechanical grippers for performing consecutive actions and an integrated circuit system to monitor surrounding humidity changes. This work provides inspiration to develop advanced nanocomposite materials for smart devices that require multifunction integration.

ULTRASOUND COUNTERACTS INFLAMMATION AND INDUCES CHONDROGENIC DIFFERENTIATION OF ASCS IN 3D PIEZOELECTRIC HYDROGELS

In cartilage tissue engineering (TE),new solutions are needed to effectively drive chondrogenic differentiation of mesenchymal stromal cells in both normal and inflammatory milieu. Ultrasound waves represent an interesting tool to facilitate chondrogenesis. In particular, low intensity pulsed ultrasound (LIPUS)has been shown to regulate the differentiation of adipose mesenchymal stromal cells. Hydrogels are promising biomaterials capable of encapsulating MSCs by providing an instructive biomimetic environment, graphene oxide (GO) has emerged as a promising nanomaterial for cartilage TE due to its chondroinductive properties when embedded in polymeric formulations, and piezoelectric nanomaterials, such as barium titanate nanoparticles (BTNPs),can be exploited as nanoscale transducers capable of inducing cell growth/differentiation. The aim of this study was to investigate the effect of dose-controlled LIPUS in counteracting inflammation and positively committing chondrogenesis of ASCs embedded in a 3D piezoelectric hydrogel.ASCs at 2*106 cells/mL were embedded in a 3D VitroGel RGD® hydrogel without nanoparticles (Control) or doped with 25 µg/ml of GO nanoflakes and 50 µg/ml BTNPs.The hydrogels were exposed to basal or inflammatory milieu (+IL1β 10ng/ml)and then to LIPUS stimulation every 2 days for 10 days of culture. Hydrogels were chondrogenic differentiated and analyzed after 2,10 and 28 days. At each time point cell viability, cytotoxicity, gene expression and immunohistochemistry (COL2, aggrecan, SOX9, COL1)and inflammatory cytokines were evaluated.Ultrasound stimulation significantly induced chondrogenic differentiation of ASCs loaded into 3D piezoelectric hydrogels under basal conditions: COL2, aggrecan and SOX9 were significantly overexpressed, while the fibrotic marker COL1 decreased compared to control samples. LIPUS also has potent anti-inflammatory effects by reducing IL6 and IL8 and maintaining its ability to boost chondrogenesis.These results suggest that the combination of LIPUS and piezoelectric hydrogels promotes the differentiation of ASCs encapsulated in a 3D hydrogel by reducing the inflammatory milieu, thus representing a promising tool in the field of cartilage TE.Acknowledgements: This work received funding from the European Union's Horizon 2020 research and innovation program, grant agreement No 814413, project ADMAIORA (AdvanceD nanocomposite MAterIals for in situ treatment and ultRAsound-mediated management of osteoarthritis).

PH-dependent synthesis of CeO2-ZnO nanocomposite for enhanced environmental remediation of endosulfan and dimethoate pesticides

This research aims to tackle significant challenges related to the synthesis and utilization of advanced nanocomposite materials in environmental remediation, specifically focusing on pesticide degradation. The synthesis of CeO2-ZnO nanocomposites employs both co-precipitation and hydrothermal methods, with the inclusion of the zwitterionic surfactant (SB-12) as a surface modifier. The modulation of pH levels during the synthesis of CeO2-ZnO nanocomposites allows for the optimization of crucial reaction parameters. Notably, it is observed that nanocomposites prepared at pH 9 exhibit the smallest average particle size. To comprehensively characterize these prepared nanocomposites, various analytical techniques such as FTIR, XRD, DR-UV/Vis, TEM/EDS, and Nano particle size analysis are employed. The FTIR results reveal a reduced presence of impurities at higher pH levels. Notably, the CeO2-ZnO nanocomposites synthesized via the hydrothermal method at pH 9 exhibit polyhedral nanostructures. The research's significant contribution lies in the practical application of these nanocomposites for the degradation of highly toxic and persistent organochlorine and organophosphorus pesticides, particularly Endosulfan and Dimethoate. These nanoparticles demonstrate remarkable pesticide degradation capabilities, with a particular emphasis on their high effectiveness against Endosulfan. The potential implications of this work extend to areas such as environmental protection, sustainable agriculture, and the remediation of pesticide-contaminated ecosystems.

FeOOH-polypyrrole-multiwalled carbon nanotube ternary nanocomposite fabricated by liquid-liquid co-extraction technique for supercapacitors application

FeOOH-polypyrrole-multiwalled carbon nanotube (FeOOH-PPy-MWCNT) ternary nanocomposite for supercapacitor negative electrodes are prepared by liquid-liquid co-extraction (LLCE) technique using decylphosphonic acid (DPPA) as efficient co-extractor. LLCE offers advantages of reduced agglomeration and facilitates mixing of the individual components. This technique allows direct particle transfer from the reaction medium to the electrode fabrication slurry. The mechanism of LLCE extraction is analyzed. The synergetic effect of FeOOH, PPy and MWCNT significantly enhances charge storage properties of the FeOOH-PPy-MWCNT ternary nanocomposite electrodes. The FeOOH-PPy-MWCNT ternary nanocomposite electrode shows an integral capacitance of 5.1 F cm−2 (137.9 F g−1) in a negative potential window, which is significantly higher than capacitances of binary FeOOH-MWCNT and PPy-MWCNT nanocomposites. Moreover, the ternary composite offers advantages of a larger voltage window. Testing results for the ternary composites at different electrode potentials show reduced AC impedance. The asymmetric supercapacitor device composed of FeOOH-PPy-MWCNT anode and MnO2-MWCNT cathode exhibits a high areal capacitance of 2.5 F cm−2 at scanning rate of 2 mV s−1 in a voltage window of 1.6 V at an extremely small impedance. This facile LLCE fabrication technique opens a door for fabrication of advanced nanocomposite materials for supercapacitor applications.

Fabrication of Dye‐Sensitized Solar Cells Based on Novel Mixed Tungsten–Molybdenum and Tungsten–Titanium Oxides Nanoparticles Prepared by Impulse Underwater Plasma

Herein, a new method for synthesizing advanced nanocomposite materials based on tungsten, molybdenum, and titanium oxides by pulsed underwater plasma is reported. This is an environmentally friendly, energy‐saving, and simple method for obtaining bimetallic oxide nanoparticles with inhomogeneous defect structures. The chemical composition and morphology of the obtained particles are explored by electron microscopy and X‐ray diffraction spectroscopy. Four types of mixed‐oxide particles of tungsten–molybdenum and tungsten–titanium are synthesized and used to make the photoanodes for dye‐sensitized solar cells (DSSCs). The best DSSC shows a fill factor of 51% and a short‐circuit current density of 4.8 mA cm−2, resulting in a conversion efficiency of 4.11% and an improvement over the cells prepared from pure titanium or tungsten oxides.

Advanced nanocomposite materials made of TiC nanocrystals in situ immobilized in SiC foams with boosted spectral selectivity

Nanocomposites made of TiC nanocrystals distributed in a highly crystallized SiC matrix to boost the spectral selectivity of SiC.

Study of Molecular-Level Dispersion of Pristine Graphene in Aqueous Media via Polyvinyl Alcohol Coil Physisorption.

Graphene has been widely used as a nanofiller in advanced electronic devices and nanocomposite materials to achieve enhanced electronic, mechanical, and barrier properties. Adequate polymers play the role of the composite matrix and can assist in the liquid-phase exfoliation of pristine graphene without any heavy chemical modification and the detriment of the properties of graphene. This stabilization mechanism is generally attributed to the steric forces formed between the polymer-adsorbed adsorbent. However, the key influence of the polymer concentration on the maximum graphene content in the colloidal solutions is still unclear. In this study, three different molar weights of water-soluble polyvinyl alcohol (PVA) were used for graphene dispersion. The influence of the PVA concentration on the graphene dispersion was systematically studied. Based on Flory's theory, we first proposed a model to describe the polymer adsorption process in the graphene/PVA/water ternary system in the "dilute" regime and simulated the adsorption-free energy changes during this transformation. This model is in good agreement with the experimental results and explains the critical polymer concentration, Cc, allowing the optimization of the graphene/polymer ratio. This fundamental understanding of polymer physisorption on 2D materials provides a simple method for producing nanocomposites with controlled nanosheet/polymer ratios and structures, which are of great interest for energy devices and biomaterials.

Decorated Au NPs on lignin coated magnetic nanoparticles: Investigation of its catalytic application in the reduction of aromatic nitro compounds and its performance against human lung cancer

In the recent years, bio-functionalized noble metal doped advanced magnetics nanocomposite materials has been materialized as potential featured catalysts in diverse applications. In this connection, we report herein a novel biogenic lignin driven Au nanoparticle supported Fe3O4 composite material. The procedure is free from any harsh reducing or stabilizing agent. Morphology and structural features were assessed following different physicochemical methodologies like FT-IR, FE-SEM, TEM, EDS, XRD, VSM and ICP-OES techniques. Thereafter, the [Fe3O4/Lignin/Au] material was successfully employed in the efficient reduction of different nitroarenes in aqueous medium. The process was monitored over UV–Vis spectroscopic study. Excellent yields were achieved with a range of diverse functionalized nitroarenes within 10–45 min of reaction. The nanocatalyst was recycled 10 times without any significant loss of catalytic activity. Distinctiveness of the material's activity was validated by comparing the results in the reduction of 4-nitrophenol. Furthermore, the prepared [Fe3O4/Lignin/Au] nanocomposite system exhibited outstanding antioxidant and anticancer effects against five lung cancer cell lines, such as, BICR 3, BICR 78, CALU 1, ChaGo-K-1, and A549. Cytotoxicity assay was determined in terms of % cell viability following MTT protocol. The corresponding IC50 values were obtained as 47, 31, 19, 25, and 31 μg/mL respectively.

Predictive modeling and computational machine learning simulation of adsorption separation using advanced nanocomposite materials

Adsorption process was simulated in this study for removal of Hg and Ni from water using nanocomposite materials. The used nanostructured material for the adsorption study was a combined MOF and layered double hydroxide, which is considered as MOF-LDH in this work. The data were obtained from resources and different machine learning models were trained. We selected three different regression models, including elastic net, decision tree, and Gradient boosting, to make regression on the small data set with two inputs and two outputs. Inputs are Ion type (Hg or Ni) and initial ion concentration in the feed solution (C 0 ), and outputs are equilibrium concentration (Ce) and equilibrium capacity of the adsorbent (Qe) in this dataset. After tuning their hyper-parameters, final models were implemented and assessed using different metrics. In terms of the R2-score metric, all models have more than 0.97 for Ce and more than 0.88 for Qe. The Gradient Boosting has an R2-score of 0.994 for Qe. Also, considering RMSE and MAE, Gradient Boosting shows acceptable errors and best models. Finally, the optimal values with the GB model are identical to dataset optimal: (Ion = Ni, C 0 = 250, Ce = 206.0). However, for Qe, it is different and is equal to (Ion = Hg, C0 = 121.12, Ce = 606.15). The results revealed that the developed methods of simulation are of high capacity in prediction of adsorption for removal of heavy metals using nanostructure materials.

Photocatalytic Degradation of Rhodamine B Dye by Nanocomposites: A Review

Pollution by textile dyes on waterbodies is an issue for both human health and the environment. To remove/degrade dyes, many approaches (coagulation, membrane separation, and adsorption) have been investigated. However, the use of semiconductor-assisted materials in conjunction with sustainable solar energy has emerged as a possible solution to the problem. Although single component photocatalysts have been tested, composites of semiconductor materials are being employed owing to their low efficiency and stability due to the high recombination rate electron-hole pair and inefficient visible light absorption. By combining two or more semiconductor components, semiconductor heterojunction systems are created. Overall stability is increased by the synergistic impact of their features, such as adsorption and better charge carrier movement. This paper discusses current advances in advanced nanocomposite materials utilized as photocatalysts, as well as the utilization of heterojunctions, crystallinity, and doping to improve photocatalytic characteristics. The conclusion includes a summary, research gaps, and a forecast for the future. This study will aid in the development of efficient heterostructure photodegradation systems by providing a comprehensive appraisal of recent advances in demonstrating effective nanocomposites for photodegradation of Rhodamine B dye under ideal circumstances.

Nanoarchitecture of Novel 3D Ion Transferring Channel Containing Composite Solid Polymer Electrolyte Membrane Based on Holey Graphene Oxide and Chitosan Biopolymer

In three-dimensional (3D) nanoarchitecture arena, two-dimensional (2D) nanostructured graphene oxide (GO) and its derivatives have been emerged as a promising choice of advanced additive materials due to their outstanding properties: high specific surface area (2630 m2g-1), flexibility, light weight, diverse functionality, super mechanical and thermal stability. Particularly, holey graphene oxide (HGO)—single atom thick unique 2D porous nanosheet is obtained from exfoliation of functional GO—a class of graphene sheet with abundant nanopore in their plane; can potentially be used for designing, fabricating and evaluating advanced 3D nanocomposite materials for the development of demandable renewable energy technologies including next generation of solid-state Li+ and Na+ rechargeable batteries. Having been the most significant, momentous, and effectual commercial energy storage devices over the past decade, however, lithium-ion batteries (LIBs) have some key limitations: flammability, poor thermal, and mechanical stability. To overcome these existing limitations, incorporation of ceramic or polymer-based solid-state electrolytes into the LIBs are being explosively focused by the energy storage research community because of their full solid-state condition and tunable molecular level engineering scope.In this research work, a novel 3D nanocomposite solid polymer electrolyte membrane (SPEM) has been successfully developed based on 2D-HGO and chitosan (CH) biopolymer—naturally occurring only alkaline polysaccharide obtained from industrial shrimp shells, super cheap, nanostructured, non-toxic, completely biodegradable, also abundant in nature. In addition, a facial and cost-effective solution-casting technique has been utilized to fabricate SPEM and applied as a solid-state polymer electrolyte for next generation of flexible and wearable rechargeable LIB technology. To investigate the structural, morphological, thermal, mechanical, and electrochemical performance of as prepared SPEM, so far, a comprehensive characterization has been done with the help of SEM, TEM, XRD, TGA, DSC, FTIR, Raman, elemental analysis, tensile strength test, and electrochemical impedance spectroscopy techniques. The SEM analysis of as-prepared flexible, wearable, free-standing, and super thin (~0.08 mm) SPEM depicts the coherently aligned 2D-HGO nanosheets formed a uniform and strong interconnecting 3D ion transfer channels with the host CH biopolymer. Moreover, 1wt% HGO, almost evenly distributed nanofiller SiO2 particles along with polyvinylpyrrolidone (PVP) polymer binder played an important role to generate better mechanical and electrochemical properties in SPEM. Thus, SPEM exhibited impressive ionic conductivity (6.44 x 10-3 Scm-1 at 23.1 oC and 1.02×10-2 Scm-1 at 70oC), a high level of tensile strength (5.87 MPa) as well as 672% and 93.7% increase of tensile strength than that of without HGO additive and GO based nanocomposite membranes respectively. In fact, very low activation energy (Ea = 0.08 eV) value shows the approval of easy lithium-ion diffusion capability in the SPEM system. In addition, fast ion transfer mechanism in SPEM has been investigated with an in-depth dielectric study that tells us the mainly hopping mechanism is dominating in the novel 3D architecture of SPEM. Besides, the obtained impressive electrochemical and mechanical properties of as-prepared SPEM could assist to understand the further fundamental aspects and impacts of SPEM in the application of LIB technology.

High Performance Polycarbonate Nanocomposites Mechanically Boosted with Titanium Carbide in Material Extrusion Additive Manufacturing.

Herein, a polycarbonate (PC) polymer is melt extruded together with titanium carbide (TiC) nano powder for the development of advanced nanocomposite materials in material extrusion (MEX) 3D printing. Raw material for the 3D printing process was prepared in filament form with a thermomechanical extrusion process and specimens were built to be tested according to international standards. A thorough mechanical characterization testing course (tensile, flexural, impact, microhardness, and dynamic mechanical analysis-DMA) was conducted on the 3D printed specimens. The effect of the ceramic filler loading was also investigated. The nanocomposites’ thermal and stoichiometric properties were investigated with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy-dispersive X-ray spectroscopy (EDS), and Raman respectively. The specimens’ 3D printing morphology, quality, and fracture mechanism were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM) respectively. The results depicted that the addition of the filler decidedly enhances the mechanical response of the virgin polymer, without compromising properties such as its processability or its thermal stability. The highest improvement of 41.9% was reported for the 2 wt.% filler loading, making the nanocomposite suitable for applications requiring a high mechanical response in 3D printing, in which the matrix material cannot meet the design requirements.

Engineering Nanostructured Antimony-Based Anode Materials for Sodium Ion Batteries

Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries (LIBs) for energy storage due to their low cost and the large abundance of sodium resources. The search for new anode materials for SIBs has become a vital approach to satisfying the ever-growing demands for better performance with higher energy/power densities, improved safety and a longer cycle life. Recently, antimony (Sb) has been extensively researched as a promising candidate due to its high specific capacity through an alloying/dealloying process. In this review article, we will focus on different categories of the emerging Sb based anode materials with distinct sodium storage mechanisms including Sb, two-dimensional antimonene and antimony chalcogenide (Sb2S3 and Sb2Se3). For each part, we emphasize that the novel construction of an advanced nanostructured anode with unique structures could effectively improve sodium storage properties. We also highlight that sodium storage capability can be enhanced through designing advanced nanocomposite materials containing Sb based materials and other carbonaceous modification or metal supports. Moreover, the recent advances in operando/in-situ investigation of its sodium storage mechanism are also summarized. By providing such a systematic probe, we aim to stress the significance of novel nanostructures and advanced compositing that would contribute to enhanced sodium storage performance, thus making Sb based materials as promising anodes for next-generation high-performance SIBs.

Silica hairy nanoparticles: a promising material for self-assembling processes.

"Hairy" nanoparticles (HNPs), i.e. inorganic NPs functionalized with polymer chains, are promising building blocks for the synthesis of advanced nanocomposite (NC) materials having several technological applications. Recent evidence shows that HNPs self-organize in a variety of anisotropic structures, resulting in an improvement of the functional properties of the materials, in which are embedded. In this paper, we propose a three-step colloidal synthesis of spherical SiO2-HNPs, with controlled particle morphology and surface chemistry. In detail, the SiO2 core, synthesized by a modified Stöber method, was first functionalized with a short-chain amino-silane, which acts as an anchor, and then covered by maleated polybutadiene (PB), a rubbery polymer having low glass transition temperature, rarely considered until now. An extensive investigation by a multi-technique analysis demonstrates that the synthesis of SiO2-HNPs is simple, scalable, and potentially applicable to different kind of NPs and polymers. Morphological analysis shows the overall distribution of SiO2-HNPs with a certain degree of spatial organization, suggesting that the polymer coating induces a modification of NP-NP interactions. The role of the surface PB brushes in influencing the special arrangement of SiO2-HNPs was observed also in cis-1,4-polybutadiene (cis-PB), since the resulting NC exhibited the particle packing in "string-like" superstructures. This confirms the tendency of SiO2-HNPs to self-assemble and create alternative structures in polymer NCs, which may impart them peculiar functional properties.

Potential applications of advanced nano-composite materials for space payload

ABSTRACTTheir attractive mechanical, electrical & thermal properties, superior to state-of-art materials currently being used, results in improving the performance of polymer matrix composites. The challenge is to identify the required potential application of CNT composites for space use. Moreover, it needs space qualifications including material, process & product qualification. This review paper states a few potential applications of Nanofiller composites for space payload components. It also states challenges and requirements for space applications as well as space qualification.

The effect of benzothiazolium surfactant modified montmorillonite content on the properties of polyamide 6 nanocomposites

The study of organoclay is a vital subject in current research since various organo-modified clays have become an attractive class of organic–inorganic hybrid materials owing to their potential application as precursors in the field of polymer nanocomposites. In the present investigation, a new benzothiazolium salt, N-dodecyl-2-methylbenzothiazolium iodide (Mbzt) was designed and synthesized for use as sodium montmorillonite (NaMt) modification by the traditional cation exchange reaction. The successful intercalation of Mbzt surfactant into the montmorillonite interlayer has been confirmed by FTIR, XRD and TGA analysis. The XRD analysis demonstrated that the intercalated surfactant adopted a tilted monolayer arrangement. The resulting benzothiazolium-modified (Mbzt-Mt) displayed a high thermal stability as compared to the unmodified (NaMt). The desired organoclay was then subsequently mixed with polyamide 6 (PA6) by melt extrusion in a twin-screw extruder. The thermal and morphological properties of the resulting PA6/Mbzt-Mt nanocomposites were evaluated by thermogravimetric analysis (TGA) and scanning electronic microscopy (SEM). TGA analysis reveal that the thermal stability of PA6 nanocomposites slightly decrease (393–391 °C) with particles loading from 1 to 5 wt%, against raw PA6 (407 °C), while an increase in the charred residue up to 5.1% was clearly observed. In addition, a good overall dispersion of the organoclay particles in the PA6 matrix was readily observed by SEM images. The mechanical and rheological properties of nanocomposites were also evaluated. A linear increase in Young's modulus and tensile strength from the use of particles when compared to the neat PA6. In particular, a 26% increase in Young's modulus, a 11.5% increase in tensile strength for the case of PA6 nanocomposites containing 5 wt% of clay as compared to that of pure PA6. From a rheological point of view, the addition of organoclay affect the linear viscoelastic behavior of the PA6 matrix, the viscosity of nanocomposites are higher than that of pure PA6, the organoclays particles restrict the movement of PA6 macromolecular chains, which increases the viscosity. These findings are important and relevant to the elaboration of low-cost organoclay as nano-reinforcement for advanced nanocomposite materials in various application.

Transferability of Polymer Chain Properties between Coarse-Grained and Atomistic Models of Natural Rubber Molecule Validated by Molecular Dynamics Simulations

In this study, we have successfully parameterized the coarse-grained (CG) model of cis-1,4-polyisoprene (main component of natural rubber) based on the MARTINI force field. An isoprene monomer is mapped into one bead of CG model. The structure, bulk and thermodynamics properties of cis-1,4-polyisoprene with new CG model are well comparable to the atomistic simulation model and experiment. Our CG model of cis-1,4-polyisoprene will be helpful to study in the advanced rubber nanocomposite materials.

Multisite catalyst mediated polymer nanostructure formation and self-reinforced polyethylene reactor blends with improved toughness/stiffness balance

Abstract The design of supported two- and three-site catalysts for ethylene polymerization and tailoring nanophase-separated polyethylene reactor blends represents the key to the development of advanced all-polyethylene nanocomposite materials exhibiting substantially improved performance and high resource-, eco- and energy efficiency. Two or three different single-site catalysts independently produce high density polyethylene (HDPE), ultrahigh molecular weight polyethylene (UHMWPE) and PE wax on the same catalyst support. Since this catalyst-mediated nanophase separation prevents UHMWPE entanglement, typical for conventional homogeneous reactor blends, much higher UHMWPE content up to 30 wt % is incorporated in the presence of PE wax without impairing injection molding. During melt processing the shear-induced oriented UHMWPE crystallization affords shish-kebab-fiber-like nanostructures. This accounts for effective PE self-reinforcement paralleled by simultaneous improvement of stiffness, strength and toughness. Hence, this strategy holds great promise for converting commodity PE into high performance plastics and single component PE composites, entering the performance range currently claimed by glass fiber reinforced PE.