Synthesis of a soluble polyaniline–ferrite composite: magnetic and electric properties

We report the preparation of a processible magnetite/polyaniline (Fe₃O₄/PANI) nanocomposite, containing dodecylbencensulfonic acid (DBSA) as a surfactant and dopant, with both magnetic and conducting properties. Different amounts of Fe₃O₄ nanoparticles were successfully disposed with FeCl₃ solution to prevent their aggregation in the solution by the application of common ion effect. The magnetic properties of the resulting composites were investigated by a quantum design magnetometer (PMPS). The (Fe₃O₄/PANI) nanocomposite showed at 300 K no loop of hysteresis indicating the superparamagnetic nature. The saturation magnetization varies from 0.167 to 28.45 emu/g with increasing Fe₃O₄ content. Zero field cooling (ZFC) and Field cooling (FC) profiles showed that the polyaniline matrix allows each ferrite nanoparticles to behave independently and interparticle interactions are not important for iron oxide content lower than 36 wt.%. The electrical conductivity of composites was found to be higher than that of the pure PANI in spite of the insertion of the insulating material Fe₃O₄ particles. It is noticeable that conductivity increases with low Fe₃O₄ particles content and then decreases. Structural characterization by X-ray diffraction (XRD), UV spectroscopy and thermogravimetric analysis (TGA) have been performed.     

Preparation and Characterization of Dentin Phosphophoryn‐Derived Peptide‐Functionalized Lignin Nanoparticles for Enhanced Cellular Uptake

The surface modification of nanoparticles (NPs) using different ligands is a common strategy to increase NP?cell interactions. Here, dentin phosphophoryn‐derived peptide (DSS) lignin nanoparticles (LNPs) are prepared and characterized, the cellular internalization of the DSS‐functionalized LNPs (LNPs‐DSS) into three different cancer cell lines is evaluated, and their efficacy with the widely used iRGD peptide is compared. It is shown that controlled extent of carboxylation of lignin improves the stability at physiological conditions of LNPs formed upon solvent exchange. Functionalization with DSS and iRGD peptides maintains the spherical morphology and moderate polydispersity of LNPs. The LNPs exhibit good cytocompatibility when cultured with PC3‐MM2, MDA‐MB‐231, and A549 in the conventional 2D model and in the 3D cell spheroid morphology. Importantly, the 3D cell models reveal augmented internalization of peptide‐functionalized LNPs and improve antiproliferative effects when the LNPs are loaded with a cytotoxic compound. Overall, LNPs‐DSS show equal or even superior cellular internalization than the LNPs‐iRGD, suggesting that DSS can also be used to enhance the cellular uptake of NPs into different types of cells, and release different cargos intracellularly.     

Nanostructured systems based on SBS epoxidized triblock copolymers and well-dispersed alumina/epoxy matrix composites

In the present research, the effect of addition of (1 wt.% and 3 wt.%) alumina nanoparticles (Al₂O₃) to epoxy modified by poly(styrene-b-butadiene-b-styrene) (SBS) epoxidized triblock copolymer was studied. The microstructure of final hybrid composites was studied with atomic force microscopy (AFM). Composites showed homogeneously dispersed Al₂O₃ nanoparticles in the epoxy matrix containing polystyrene (PS) microphase separated nanodomains. Dynamic mechanical analyses (DMA), flexural and fracture toughness investigations were carried out. The glass transition temperature of epoxy matrix has been retained unchanged by the addition of Al₂O₃ nanoparticles. The nanostructured epoxy systems based on SBS epoxidized triblock copolymer and well-dispersed Al₂O₃ nanoparticles allowed an increase in fracture toughness maintaining the transparency and stiffness of neat epoxy.     

Template-Directed Polymerization of Binary Acrylate Monomers on Surface-Activated Lignin Nanoparticles in Toughening of Bio-Latex Films

Fabricating bio-latex colloids with core–shell nanostructure is an effective method for obtaining films with enhanced mechanical characteristics. Nano-sized lignin is rising as a class of sustainable nanomaterials that can be incorporated into latex colloids. Fundamental knowledge of the correlation between surface chemistry of lignin nanoparticles (LNPs) and integration efficiency in latex colloids and from it thermally processed latex films are scarce. Here, an approach to integrate self-assembled nanospheres of allylated lignin as the surface-activated cores in a seeded free-radical emulsion copolymerization of butyl acrylate and methyl methacrylate is proposed. The interfacial-modulating function on allylated LNPs regulates the emulsion polymerization and it successfully produces a multi-energy dissipative latex film structure containing a lignin-dominated core (16% dry weight basis). At an optimized allyl-terminated surface functionality of 1.04 mmol g⁻¹, the LNPs-integrated latex film exhibits extremely high toughness value above 57.7 MJ m⁻³. With multiple morphological and microstructural characterizations, the well-ordered packing of latex colloids under the nanoconfinement of LNPs in the latex films is revealed. It is concluded that the surface chemistry metrics of colloidal cores in terms of the abundance of polymerization-modulating anchors and their accessibility have a delicate control over the structural evolution of core–shell latex colloids.     

Preparation and characterization of thermo-, pH-, and magnetic-field-responsive organic/inorganic hybrid microgels based on poly(ethylene glycol)

Nanocomposite microgels are a new class of intelligent materials because of their fast response time, large surface area, and so on. In this study, we demonstrate a new kind of multiple stimulus-responsive organic/inorganic hybrid microgels by combining dual stimuli-responsive poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol)methacrylate-co-acrylic acid) (PMOA) microgels with magnetic attapulgite/Fe₃O₄ (AT–Fe₃O₄) nanoparticles. AT–Fe₃O₄ nanoparticles were introduced into the dual-responsive (temperature and pH) PMOA microgels network by in situ polymerization. The responsive behaviors, microstructures, and the interaction between AT–Fe₃O₄ and PMOA microgels matrix of the prepared microgels were systematically characterized using field emission scanning electron microscopy, particle size and Zeta potential analyzer, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. The results showed that the AT–Fe₃O₄ nanoparticles dispersed well in the microgel matrix, and the nanoparticles could be stably present in PMOA without phase separation because of the hydrogen bond (H-bond) interactions between AT–Fe₃O₄ nanoparticles and PMOA matrix. In addition, the multifunctional AT–Fe₃O₄/PMOA nanocomposite microgels had both temperature/pH sensitivity and magnetic functionality.     

Characteristic analysis of Fe3O4 nanoparticles modified by oleic acid and undecylenic acid

Carbonization of magnetic polymer microspheres is one of the methods for the preparation of magnetic carbon materials. Fe₃O₄ magnetic particle characteristics considerably influence the magnetic content and size distribution of magnetic polymer microspheres. The characteristics of Fe₃O₄ nanoparticles modified by oleic acid (OA) and undecylenic acid (UA) were analyzed by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, dynamic laser light scattering, thermogravimetry/differential thermogravimetry, vibrating sample magnetometer, and water contact angle. Fe₃O₄ nanoparticles modified by OA and UA are nearly spherical and exhibit superparamagnetism. Fe₃O₄ particle size and saturation magnetization are slightly influenced by the OA and UA composition. OA and UA both are chemically adsorbed onto Fe₃O₄ as bidentate chelates. OA shows easier adsorption onto Fe₃O₄ than UA. OA groups have an expanded arrangement on OA@Fe₃O₄, whereas UA groups have a condensed arrangement on UA@Fe₃O₄. Particle lipophilicity decreases and particle clustering increases with decreasing OA content and increasing UA content on OA-UA@Fe₃O₄ nanoparticles.     

Facile synthesis of capped γ-Fe2O3 and Fe3O4 nanoparticles

Facile methods for the selective preparation of capped iron oxide nanoparticles (γ-Fe₂O₃, Fe₃O₄) are described. The magnetic oxides are obtained via oxidative transformation of an iron hydroxide gel using H₂O₂ or (NH₄)₂S₂O₈ solutions as oxidants. Capping with oleic or other aliphatic acids is established simultaneously in one step by adding a toluene solution of the capping agent and refluxing the resulting biphase system. The method is simple, soft and affords nanoparticles of γ-Fe₂O₃ or Fe₃O₄ of controlled size depending on the reaction conditions. The capped nanoparticles are readily soluble in organic or aqueous media according to the nature of the sheath surrounding the surface of the particles, providing stable and high concentration ferrofluids.     

Tunable photonic crystals from emulsion containing magnetic nanoparticles

We report a simple approach to synthesize emulsion of oleic acid (OA) containing Fe₃O₄-OA nanoparticles as magnetic building block of photonic crystals by combined chemical co-precipitation and emulsification technology. The emulsion droplets exhibit dominant size distribution of 80-110 nm and superparamagnetic behavior. A high loading fraction of magnetic compounds Fe₃O₄ in emulsion of 72% was achieved by the approach. Upon application of a magnetic field, the emulsion droplets in water facilely self-assemble into photonic crystals, and the stop bands could be tuned in ranging visible spectrum by moving position of magnet. The method to synthesize emulsion with high magnetic loading fraction should facilitate preparation of tunable photonic crystals and expand their application.     

Structural investigations of Y2O3 dispersoids during mechanical milling and high-temperature annealing of Fe-15Y2O3-xTi (x = 0–15) model ODS alloys

A model Oxide Dispersion Strengthened (ODS) alloy powder of composition Fe – 15 wt. % Y₂O₃ – x wt. % Ti (x = 0, 2, 5, 10 and 15) were synthesized by high energy mechanical milling in Ar atmosphere for a prolonged duration of 60 h. Synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations suggested the amorphisation of Y₂O₃ nano-crystallites, irrespective of Ti content, which is further studied by Raman spectroscopy. The Raman spectroscopy analysis confirms the presence of YO bonding in the milled powder and ruled out the possibility of elemental dissociation of Y₂O₃ and dissolution into the Fe matrix. Annealing of the milled powders containing different amounts of Ti led to formation of different types of oxide complexes which were also studied using synchrotron XRD and TEM studies. The role of Ti in refining the dispersoids through formation of Y_1.6Ti_1.8Fe_0.4O_6.6 is established through these studies.     

Feasibility of using Y2Ti2O7 nanoparticles to fabricate high strength oxide dispersion strengthened Fe–Cr–Al steels

Addition of Al can improve the corrosion resistance of oxide dispersion strengthened (ODS) steels. However, Al reacts with Y₂O₃ to form large Y–Al–O particles in the steels and deteriorates their mechanical properties. Herein, we successfully prepared Y₂Ti₂O₇ nanoparticles (NPs) by the combination of hydrogen plasma-metal reaction (HPMR) and annealing. Y₂Ti₂O₇ NPs with contents of 0.2 or 0.6 wt.% were then added into the Fe–14Cr–3Al–2W–0.35Ti (wt.%) steel to substitute the conventional Y₂O₃ NPs by mechanical alloying (MA). The Y₂Ti₂O₇ NPs transformed into amorphous-like structure after 96 h MA. They crystallized with a fine size of 7.4 ± 3.7 nm and shared a semi-coherent interface with the matrix after hot isostatic pressing (HIP) of the ODS steel with 0.6 wt.% Y₂Ti₂O₇. With the increasing Y₂Ti₂O₇ content from 0.2 to 0.6 wt.%, the tensile strength of the ODS steel increased from 1238 to 1296 MPa, which was much higher than that (949 MPa) of the ODS steel added with Y₂O₃. The remarkably improved mechanical properties of the Al-containing ODS steels were attributed to the increasing number density of Y₂Ti₂O₇ nanoprecipitates. Our work demonstrates a novel route to fabricate high performance ODS steels with both high mechanical strength and good corrosion resistance.     

Influence of La2O3 nanoparticle additions on microstructure,wetting, and tensile characteristics of Sn–Ag–Cu alloy

In this study, the effect of La₂O₃ nanoparticles (0, 0.01, 0.03, 0.05 and 0.1 wt.%) has been investigated in Sn–3.0Ag–0.5Cu (SAC-305) alloy. The various soldering properties have been tested, such as wettability, microstructural evolution, intermetallic compound formation, micro-hardness, tensile strength, and fracture analysis of tensile tested samples. La₂O₃ nanoparticles are added in the Sn–3.0Ag–0.5Cu alloy by mechanical mixing of powders and melting. The structural and morphological features of the samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electron probe micro-analyzer (EPMA). The experimental results indicate that the best combination of microstructural, wetting and tensile properties is obtained at 0.05 wt.% La₂O₃ in the solder matrix. The sample reinforced with 0.05 wt.% La₂O₃ i.e., SAC-0.05 La2O3 exhibits ~ 18% increase in microhardness, ~ 26% increase in the ultimate tensile strength (UTS), and ~ 14% elongation due to the adsorption of high surface energy of La₂O₃ nanoparticles in the matrix.     

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

Oleic-acid-coated CoFe₂O₄ nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism dominates to the region where mono-domain ferrimagnetism dominates the magnetic properties.     

Low temperature preparation of the Zn<Subscript>2</Subscript>SiO<Subscript>4</Subscript> ceramics with the addition of BaO and B<Subscript>2</Subscript>O<Subscript>3</Subscript>

The Zn₂SiO₄ ceramics with the addition of BaO and B₂O₃ are fabricated by traditional solid-state preparation process at a sintering temperature of 900 °C. The introduction of BaO and B₂O₃ to the binary system ZnO-SiO₂ is achieved by adding 10 and 20 wt. % flux BB to the mixed ZnO-SiO₂ ceramic powders pre-sintered at 1,100 °C, respectively. The chemical composition of the flux BB (50 wt.%BaO-50 wt.% B₂O₃) is located at a liquid phase zone with a temperature range of about 869–900 °C in the binary diagram BaO-B₂O₃. In addition, the introduction of BaO and B₂O₃ to the binary system ZnO-SiO₂ is also achieved by the means of a chemical combination of H₂SiO₃, H₃BO₃, ZnO and Ba(OH)₂·8H₂O, which can result in the formation of the hydrated barium borates with low melting characteristics. In turn, by the liquid sintering aid of the barium borate melts, the preparation process of the Zn₂SiO₄ ceramics can be further simplified. In the two preparation methods, the Zn₂SiO₄ ceramics with the 1.5–2.0 ZnO/SiO₂ molar ratios and the addition of a 10 wt. % flux BB can show good dielectric properties whereas the bending strength mainly depends on the microstructure of the Zn₂SiO₄ ceramics and SiO₂ content in the composition of the specimen.     

A facile route to synthesis of superparamagnetic Fe3O4–PDVB nanoworms

Fe₃O₄–polydivinylbenzene (PDVB) nanoworms were firstly synthesized by precipitation polymerization of divinylbenzene in the presence of oleic acid coated iron oxide nanoparticles. The nanoworms had superparamagnetic properties at room temperature, but ferromagnetism at 5 K. Thermogravimetric analysis curves indicated that in comparison with magnetic nanoparticles, the weight percent of iron oxide in nanoworms was slightly declined due to the formation of Fe₃O₄–PDVB nanocomposites. The superparamagnetic nanoworms could be well dispersed in ethanol, and were capable of easy separation by an external magnetic field. Overall, this provided a valuable methodology for preparation of elongated magnetic nanoparticles with high surface-to-volume ratio, which had potential applications in drug delivery/targeting, magnetic resonance imaging, and nanoprobes for diagnosis and disease treatment.     

Improvement in the hydrogen-storage properties of Mg by the addition of metallic elements Ni, Fe, and Ti, and an oxide Fe2O3

Pure Mg was employed as a starting material instead of MgH₂ in this work. The magnesium prepared by mechanical grinding under H₂ (reactive mechanical grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt.%. Ni, Fe and Ti were chosen as metallic transition elements to be added. Fe₂O₃ was selected as an oxide to be added. Samples Mg–14Ni–2Fe₂O₃–2Ti–2Fe were prepared by reactive mechanical grinding, and their hydrogen storage properties were examined and compared with those of a pure Mg sample prepared by reactive mechanical grinding under the same conditions. The Mg–14Ni–2Fe₂O₃–2Ti–2Fe sample showed much better hydrogen storage properties than the pure Mg sample. The as-milled Mg–14Ni–2Fe₂O₃–2Ti–2Fe sample did not require the activation. This sample absorbs 4.26 wt.% H for 5 min, and 4.41 wt.% H for 10 min, and 4.56 wt.% H for 60 min at n = 2. It desorbs 1.13 wt.% H for 10 min, 2.67 wt.% H for 30 min, and 3.32 wt.% H for 60 min at n = 2.     

Green synthesis of ZnO2 nanoparticles from hydrozincite and hydrogen peroxide at room temperature

A green method based on the reaction between hydrozincite (Zn₅(CO₃)₂(OH)₆) powder and hydrogen peroxide (H₂O₂, 30 wt.%) in aqueous solution at room temperature was developed for the synthesis of ZnO₂ nanoparticles. Results from X-ray diffraction, transmission electron microscopy and Raman demonstrated that the resultant products were pure cubic phase ZnO₂ nanoparticles, whose sizes were in the range of 3.1-4.2 nm. Thermogravimetric analysis indicated that between 180 and 350 °C, the as-synthesized ZnO₂ nanoparticles had a weight loss of about 16.7%, consistent with the theoretical amount (16.4%) of the O₂ released from ZnO₂ decomposition (ZnO₂ = ZnO + 1/2O₂). The present method was green, simple and cost-effective, which should be suitable for large-scale production of multifunctional ZnO₂ nanoparticles.     

Preparation of polybenzoxazine-functionalized Fe3O4 nanoparticles through in situ Diels–Alder polymerization for high performance magnetic polybenzoxazine/Fe3O4 nanocomposites

Hybrids and nanocomposites of polymer and magnetic Fe₃O₄ nanoparticles have been utilized as magnetically-responsive materials and magnetically-directed nanoparticles. In this work, we prepare polymer-functionalized Fe₃O₄ nanoparticles through in situ Diels–Alder polymerization using maleimide-functionalized Fe₃O₄ nanoparticle as a precursor. Polybenzoxazine-functionalized Fe₃O₄ nanoparticles (MNP-PBz) have been obtained and characterized with Fourier Transform Infrared, X ray photoelectron, and Raman spectroscopies. The high saturation magnetization value of 51.9 emu g⁻¹ of the MNP-PBz nanoparticles demonstrates its superparamagnetism. Moreover, MNP-FBz has been utilized as a nanofiller for preparation of cured PBz/MNP-PBz nanocomposites, which contain various MNP-PBz contents of 67, 50, 33, and 17 wt.%. The sample of PBz/MNP-PBz-67 shows a storage modulus of 8.0 GPa, a saturation magnetization value of 37.6 emu g⁻¹, and a glass transition temperature above 380 °C. As a result, the PBz/MNP-PBz nanocomposites could be classified as magnetically-responsive high performance materials.     

Low‐Density Lipoprotein‐Mimicking Nanoparticles for Tumor‐Targeted Theranostic Applications

This study introduces multifunctional lipid nanoparticles (LNPs), mimicking the structure and compositions of low‐density lipoproteins, for the tumor‐targeted co‐delivery of anti‐cancer drugs and superparamagnetic nanocrystals. Paclitaxel (4.7 wt%) and iron oxide nanocrystals (6.8 wt%, 11 nm in diameter) are co‐encapsulated within folate‐functionalized LNPs, which contain a cluster of nanocrystals with an overall diameter of about 170 nm and a zeta potential of about ‐40 mV. The folate‐functionalized LNPs enable the targeted detection of MCF‐7, human breast adenocarcinoma expressing folate receptors, in T₂‐weighted magnetic resonance images as well as the efficient intracellular delivery of paclitaxel. Paclitaxel‐free LNPs show no significant cytotoxicity up to 0.2 mg mL^?1, indicating the excellent biocompatibility of the LNPs for intracellular drug delivery applications. The targeted anti‐tumor activities of the LNPs in a mouse tumor model suggest that the low‐density lipoprotein‐mimetic LNPs can be an effective theranostic platform with excellent biocompatibility for the tumor‐targeted co‐delivery of various anti‐cancer agents.     

Effects of Bi2O3 addition on the microstructure and electromagnetic properties of NiCuZn ferrites

Effects of Bi₂O₃ addition on the microstructural development and magnetic properties of NiCuZn ferrites were studied. For low temperature sintering (<900 °C), 0.1–1.0 wt % of Bi₂O₃ was added to the NiCuZn ferrites. The grain size and bulk density gradually increased with the increase in the Bi₂O₃ content. Above 0.5 wt % Bi₂O₃, abnormal grain growth was observed. The specimen with 0.25 wt % Bi₂O₃ showed the highest initial permeability with good quality factors and a uniform microstructure. However, the specimen with greater than 0.5 wt % Bi₂O₃ demonstrated abnormal grain growth with lower initial permeabilities and poor quality factors.     

Preparation of Fe3O4/PVA nanofibers via combining in-situ composite with electrospinning

A novel approach, combining in-situ composite method with electrospinning, was used to prepare high magnetic Fe₃O₄/poly(vinyl alcohol) (PVA) composite nanofibers. Fe₃O₄ magnetic fluids were synthesized by chemical co-precipitation method in the presence of 6 wt.% PVA aqueous solution. PVA was used as stabilizer and polymeric matrix. The resulting Fe₃O₄/PVA composite nanofibers were characterized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffractometer (XRD), respectively. These composite fibers showed a uniform and continuous morphology, with the Fe₃O₄ nanoparticles embedded in the fibers. Magnetization test confirmed that the composite fiber showed a high saturated magnetization (M_s = 2.42 emµ·g^-1) although only 4 wt.% content.