Addition Of Silica Nanoparticles Research Articles

Structural changes in nanoparticle-hydrogel composites at very low filler concentrations.

We study the enhancement of the stiffness of two families of hydrogels (polyacrylamide, PAAm, and polydimethylacrylamide, PDMA) due to the additions of very small amounts of silica nanofillers. It is well established that high concentrations of silica nanoparticles enhance the toughness of both hydrogel types, but significantly more for the PDMA based gels that adsorb readily to silica surfaces. In order to decouple the structural changes in the gels that stem either from polymerization kinetics or from the interactions between nanofillers and polymers, we use a photoinitiator for the polymerization of the composite gels that promotes the structural homogeneity of the hydrogels. We characterize both the mechanical and structural properties of the composite hydrogels as a function of nanofiller concentration, by calculating the single particle diffusion of inert polystyrene tracer particles of three different sizes. In agreement with previous experiments, we find that silica nanoparticles increase the stiffness of PAAm gels more than expected for passive fillers. Surprisingly, we find that a small addition of silica nanoparticles during gel polymerization to PDMA based hydrogels softens them. We attribute this effect to an increase of the average mesh size of the gel, allowing particles of 0.49 μm in diameter to diffuse normally through the gel, but restricting the motion of larger particles. A further increase in silica nanoparticle concentration results in the expected stiffening of the gel. PDMA based composites with a large mean pore size, as reported here, may find applications in particle separation and gentle fixation of microorganisms and cells.

Silica/polycaprolactone nanofiber scaffold variants for human periosteal cell growth.

Polycaprolactone (PCL) nanofiber scaffolds with attached cadaveric human periosteum or its cells were investigated in this study as a tissue-engineering approach to repair nonunion injuries of bone. Addition of silica nanoparticles (silica or nSiO2 ) to PCL scaffolds was examined for effects on the growth of human periosteal cells in vitro and in vivo. Electrospun PCL nanofiber (nanoPCL) scaffolds were fabricated with different silica contents (0, 0.5, and 1.0 wt %) and utilized as substrates on which periosteal cells were seeded. Human periosteal cell growth analyzed in vitro over 21 days with a PrestoBlue viability assay increased as a function of culture time on each of the three different silica/nanoPCL scaffolds. Cadaveric periosteum attached to nanoPCL scaffolds with or without silica was wrapped around allograft bone and implanted for 10 or 20 weeks in athymic (nude) mice. Histological and immunohistochemical analyses of these experiments in vivo confirmed the presence of viable cells populating the constructs after their retrieval from host mice. Osterix, a marker for osteoblasts, increased in retrieved constructs over time and indicated remodeling of the underlying allograft bone. Summary results suggest that silica/nanoPCL scaffolds may be utilized as substrates for periosteal cell and tissue expansion to augment and support clinical applications for treatment and healing of bone defects, including segmental bone injuries and nonunions. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 791-801, 2019.

Electrochemical Performance of Reduced Graphene Oxide-Silica Composite in Polyaniline

Abstract Reduced graphene oxide doped silica (rGOS) was prepared by chemical process of reduced graphene (rGO) and tetraethyl orthosilicate (TEOS). In comparison, rGOS prepared by chemical process of rGO and commercial SiO2 nanoparticles was also studied. rGOS was used in Polyaniline (PANI) to improve electrochemical performance and prepared by chemical polymerization of aniline (ANI) using ammonium persulfate oxidant with difference amounts of rGOS content. Morphological analysis of rGOS/PANI composites revealed that the nanofibers of polyaniline were intercalated between the rGO layers. With addition of silica nanoparticles, the rGOS has shown a positive effect on the electrical capacitance of PANI. The highest specific capacitance of 334.17 Fg−1 was observed for rGOS/PANI composite with TEOS. With increasing content of silica nanoparticles, the specific capacitance was found to increase. Addition of silica can increase the surface hydrophilicity in rGOS and rGOS/PANI composites and facilitate the contact between electrode material and the electrolyte.

Silica-nanoparticles in slow release supplement: preparation and characterization

The nanosilica was prepared from bamboo leaves ash by calcination method in 800°C for an hour. The result was 350 g silica from 500 g of its ash. The SEM shows a homogeneous surface of SiO2 and the EDX consists of 56,73% Si. The FTIR test indicates the Si-O-Si functional groups. The XRD shows 2θ = 21,6 which corresponds to JCPDS No. 39-1425 and 18-1170. The supplement was vitamin C tablet which prepared into slow release supplement model, by mixing of three component : generic ascorbic acid, magnesium stearate, and nanosilica in certain composition. Some assessments were carried out to determine the tablet’s characteristic: the size, homogeneity, and hardness. Physical testing of the slow-release vitamin C tablet was found to meet the requirements of tablet by Indonesian Farmakope. In vitro assessment was represented by dissolution test in simulation solutions of stomach by 0,1M HCl and the intestine by citric acid. The result showed that the dissolution of the samples were slower than the control tablets. This indicates that the addition of silica-nanoparticles affect the characteristics of slow release supplement.

Experimental investigation of enhancement of carbon dioxide foam stability, pore plugging, and oil recovery in the presence of silica nanoparticles

The influence of surface-modified silica (SiO2) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated from the pressure drop induced during foam propagation in porous media. The results clearly showed that the modified SiO2 nanoparticle-stabilized foam exhibited high stability, and the differential pressure increased in porous media by as much as three times. The addition of SiO2 nanoparticles to the foaming dispersions further mitigated the adverse effect of oil toward the foam pore plugging ability. Consequently, the oil recovery increased in the presence of nanoparticles by approximately 15% during the enhanced oil recovery experiment. The study suggested that the addition of surface-modified silica nanoparticles to the surfactant solution could considerably improve the conventional foam stability and pore plugging performance in porous media.

Exploitation of Cationic Silica Nanoparticles for Bioprinting of Large-Scale Constructs with High Printing Fidelity.

Three-dimensional (3D) bioprinting allows the fabrication of 3D structures containing living cells whose 3D shape and architecture are matched to a patient. The feature is desirable to achieve personalized treatment of trauma or diseases. However, realization of this promising technique in the clinic is greatly hindered by inferior mechanical properties of most biocompatible bioink materials. Here, we report a novel strategy to achieve printing large constructs with high printing quality and fidelity using an extrusion-based printer. We incorporate cationic nanoparticles in an anionic polymer mixture, which significantly improves mechanical properties, printability, and printing fidelity of the polymeric bioink due to electrostatic interactions between the nanoparticles and polymers. Addition of cationic-modified silica nanoparticles to an anionic polymer mixture composed of alginate and gellan gum results in significantly increased zero-shear viscosity (1062%) as well as storage modulus (486%). As a result, it is possible to print a large (centimeter-scale) porous structure with high printing quality, whereas the use of the polymeric ink without the nanoparticles leads to collapse of the printed structure during printing. We demonstrate such a mechanical enhancement is achieved by adding nanoparticles within a certain size range (<100 nm) and depends on concentration and surface chemistry of the nanoparticles as well as the length of polymers. Furthermore, shrinkage and swelling of the printed constructs during cross-linking are significantly suppressed by addition of nanoparticles compared with the ink without nanoparticles, which leads to high printing fidelity after cross-linking. The incorporated nanoparticles do not compromise biocompatibility of the polymeric ink, where high cell viability (>90%) and extracellular matrix secretion are observed for cells printed with nanocomposite inks. The design principle demonstrated can be applied for various anionic polymer-based systems, which could lead to achievement of 3D bioprinting-based personalized treatment.

Interfacial interactions in PMMA/silica nanocomposites enhance the performance of parts created by Fused Filament Fabrication

As an additive manufacturing method, Fused Filament Fabrication (FFF) is conceptually attractive due to its agility and adaptability. However, FFF-printed parts exhibit poor mechanical properties as compared to parts manufactured by traditional methods. Here, the addition of silica nanoparticles (Si NPs) into FFF-printed parts is demonstrated to markedly improve a variety of thermomechanical properties. Specifically, dynamic mechanical analysis (DMA) and tensile tests indicate that the glass transition temperature, Young's modulus, elongation at break, ultimate tensile strength, and storage and loss moduli all increase with the Si NP loading. Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) demonstrate similar hierarchical structures in all FFF-printed nanocomposites, which suggests that improvements in material properties with Si NP loading are likely due to an increasing number of hydrogen bonding interactions between PMMA matrix chains and hydroxyl groups on the Si NP surface. The potential of nanocomposite filaments to increase the thermomechanical properties of FFF-printed specimens provides a facile route to overcome limitations in FFF-printed part strength by combining the properties of hard and soft matter.

Influence of modified silica nanoparticles on phase behavior and structure properties of DPPC monolayers.

In this work, the effect of silica nanoparticles (NPs) adding to DPPC monolayer and the interaction between DPPC and silica nanoparticles are studied. Silica nanoparticles are prepared by microemulsion, meanwhile, DMDCS and APTES are used to modify silica NPs to get three types of modified silica NPs. These samples are mixed with DPPC to form mixed monolayer. By using the atomic force microscope (AFM), surface pressure-area and pressure-time isotherms, the effects of different hydrophilic-hydrophobic silica nanoparticles on the interface of lipid monolayer is analyzed. The data shows that the addition of silica nanoparticles changes the phase behavior, the collapse time and the structure of monolayer. Hydrophilic silica NPs decreases the collapse pressure and rigidity of DPPC monolayer, and makes monolayer collapse earlier since the steric hindrance leads to the resistance to compression, while hydrophobic silica NPs have less effect on monolayer in collapse pressure or rigidity but the texture of monolayer, and the addition of hydrophobic NPs causes the appearance of holes in the monolayer. We suppose that there are several possible locations of hydrophobic and hydrophilic silica nanoparticles in the air-water interface, which leads to different effects on the structure and rheological behavior of monolayer. This study can deepen the understanding on how nanoparticles affect human body since industries of nanoparticles on drug delivery, oil recovery and floatation are developing rapidly and getting more and more outside interest on a daily basis.

Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces

The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an important key of research. The study presents the results regarding the mechanical and photo-oxidation resistance of some water-based acrylic coatings containing SiO2 nanoparticles obtained by batch miniemulsion polymerization. Coating materials have been characterized in terms of hydrophobic/hydrophilic behavior, mechanical resistance and surface morphology by means of water-contact angle, and scrub resistance and atomic force microscopy (AFM) measurements depending on silica-nanoparticle content. Moreover, accelerated weathering tests were performed to estimate the photo-oxidation resistance of the coatings. The chemical and color changes were assessed by Fourier-transform infrared spectroscopy (FTIR) and colorimetric measurements. Furthermore, the nanofilled coatings were applied on two different calcareous lithotypes (Lecce stone and Carrara Marble). Its properties, such as capillary water absorption and color modification, before and after accelerated aging tests, were assessed. The properties acquired by the addition of silica nanoparticles in the acrylic matrix can ensure good protection against weathering of stone-based materials.

Fatigue life and rutting performance modelling of nanosilica/polymer composite modified asphalt mixtures using Weibull distribution

ABSTRACTThis study has investigated the fatigue and rutting performance of composite polyethylene (PE) and polypropylene (PP) asphalt mixtures with the addition of nanosilica particles (NS). In this study, a composite modified asphalt binder was prepared usingPE and PP with NS in a concentration of 1–4% by weight of bitumen. A flexural beam fatigue test using four-point flexural beam fatigue test was conducted. A Wessex wheel tracking test was also conducted to estimate the rutting deformation of the mixtures. Weibull distribution was applied to evaluate the fatigue life of the two composite mixtures at different strain levels. A parametric survival analysis was utilised to compare the reliability of the composites. Also, a Weibull failure rate function was used to fit the experimental Wessex wheel tracking rut depth results. The results showed that the fatigue life of the composite mixtures at all strain levels complied with a two-parameter Weibull distribution with a statistical coefficient of determination greater than 0.9. The survival analysis showed that the PP composites had higher reliability at all strain levels. Furthermore, a good correlation was observed between the fitted Weibull failure rate function and the experimental rut depth obtained from the Wessex wheel tracking test.

Microencapsulation of energy conversion photochromic materials with epoxy resin shell by interfacial polymerization

In this study, a novel type of photochromic spirooxazine microcapsule was prepared by interfacial polymerization between epoxy resin and polyamine compound. The effects of different process parameters on the formation, microstructure and performance of microcapsules, such as curing reaction temperature, emulsification shear rate and the addition of silica nanoparticles were studied in this paper. The morphology, microstructure, diameter and distribution, as well as the thermal stability of microencapsulated photochromic spirooxazine were also investigated by field emission scanning electron microscope, laser particle size analyzer and thermogravimetric analysis systematically. In addition, the photochromic performance of microcapsule was studied as well.

Effect on wear resistance of nanoparticles addition to a powder polyester coating through ball milling

The wear properties of a textured polyester powder coating with pyrogenic silica nanoparticles addition were evaluated. Raw powders of a commercial, textured polyester organic coating were mixed with low amounts of SiO2 nanoparticles (0.5–3 wt%) using ball milling, a simple and economical method. Nanoparticles were mixed into the powder of thermoset organic coating for 10 min in a two-body planetary ball mill. Particle size distribution of the powder was measured to evaluate the milling effect. The coatings were applied and cured in an industrial installation on aluminum substrates. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the coatings were taken to analyze the homogeneity of the organic coating. Roughness, gloss and color were measured in order to evaluate their appearance. The effect of nanoparticles on abrasive and erosion wear performances was measured. Pin-on-disk wear tests were carried out. Erosion measurements were performed with free fall of sand on the samples, a test based on ASTM D968 standard. The results showed that the milling process provides a good distribution of nanoparticles as no agglomerates were found. The addition of 0.5 wt% silica nanoparticles allows for improvement of the wear resistance of the coatings.

Micromechanical analysis of the elastic response of glass-epoxy hybrid composites containing silica nanoparticles

ABSTRACTThe effects of adding silica nanoparticles on the elastic properties of glass-epoxy hybrid composites are investigated using a micromechanical method. Influences of silica nanoparticle volume fraction and diameter, the interphase elastic modulus and thickness, the glass fiber volume fraction and aspect ratio as well as off-axis angle on the elastic properties of unidirectional glass fiber-reinforced epoxy hybrid composites containing silica nanoparticles are studied. The results reveal that the addition of silica nanoparticles can improve the elastic modulus in the transverse direction, while the axial elastic modulus is not affected by silica nanoparticles.

Thermally activated shape memory behavior of copolymers based on ethylene reinforced with silica nanoparticles

In this work, a study on the dual-shape and triple-shape memory response of poly(ethylene-co-methacrylic acid) copolymer, EMAA, and its counterpart neutralized with sodium salt, EMAA-Na has been report. Moreover, both matrices were reinforced with silica nanoparticles in different amount. Morphological, thermal and mechanical properties were studied confirming the good dispersion of the nanoparticles into both polymeric matrices. The addition of silica nanoparticles increases the mechanical response of both polymeric matrices without affecting their shape memory response leading to a possible increasing use of both polymers in the industry. Moreover, the ionomeric polymer reinforced with 1 wt.% silica nanoparticles present excellent thermally activated triple-shape memory response.

Development and characterization of sugarcane bagasse fiber and nano-silica reinforced epoxy hybrid composites

This paper presents an experimental study on the mechanical performance of sugarcane bagasse fiber reinforced epoxy composite. Tensile and flexural properties of the composites were investigated in this research. Different weightage of short fiber and fiber particulates were utilized to study their effects on the mechanical performance of the composites in terms of tensile and flexural properties. 1% of nano-silica was reinforced to investigate its effect on the mechanical performance of the composites. Hand lay-up composite molding process was used to fabricate the composite samples. During fabrication, ultrasonic mixing was carried out to study the effects on mechanical performance of the fiber particulate reinforced composites. In overall, ultrasonic mixing and addition of nano-silica particles has improved the mechanical performance of the fiber particulate composites. Morphology analysis on surface of composites has shown the removal of air bubbles and deagglomeration. 1wt% of short fiber reinforced composite exhibits the highest tensile and flexural properties among all the samples. Sugarcane bagasse particulates reinforced composites were shown to have better performance compared to short fiber reinforced composites when the wt% of the fiber increase.

Hyperbranched poly(ethyleneimine) physically attached to silica nanoparticles to facilitate curing of epoxy nanocomposite coatings

There was a hope that highly reactive nanoparticles would strongly facilitate crosslinking in epoxy-amine systems. In this work, silica (SiO2) nanoparticles are physically modified with poly(ethyleneimine) as surface modifier. The SiO2 nanoparticles were synthesized and physically decorated with poly(ethyleneimine), then the untreated and surface-treated SiO2 nanoparticles were analyzed by FTIR, TGA and SEM techniques. The results show that poly(ethyleneimine) hyperbranched molecule is successfully attached to the surface of SiO2 nanoparticles enabling epoxy ring opening. Both untreated and modified particles are impregnated into an epoxy/amine system to fabricate nanocomposite coatings. The effect of the aforementioned SiO2 nanoparticles on the curing behavior of the epoxy/amine system was investigated by means of dynamic DSC analysis. The results demonstrated that, while addition of untreated silica nanoparticles could not seriously curing reactions, the introduction of poly(ethyleneimine)-modified SiO2 facilitated crosslinking of epoxy/amine system thanks to the abundance of amine reactive groups on the particle surface that gives worth to the poly(ethyleneimine)-modified SiO2 nanoparticles as a promising nanomaterial for manufacturing highly-curable epoxy-based nanocomposite coatings.

Investigation of an Optimum Concentration for Nano-Silica Used as an Adhesive Bonding Strength Enhancer

In this paper, the effect of silica nanoparticles (nano-silica) on the bonding strength of reinforced adhesive joints was experimentally studied in five concentrations. A two-part epoxy-based adhesive (Araldite 2015) was used to bond the adherends as well as silica nanoparticles for strengthening purposes. Nano-silica was added into the adhesive by 1, 1.5, 2, 2.5 and 3 wt.%. Some adhesive joints with and without nanoparticles were tested under uniaxial loading to obtain their bonding strength. The results showed that the change in the bonding strength is a function of nanoparticles concentration. Furthermore, it was concluded that the addition of silica nanoparticles has a suitable effect on the joint strength at an optimum point, in which the joint strength takes its maximum value, and a further increase in the nanoparticles weight fraction causes the joint strength to decrease.

The influence of silica nanoparticles on thermal degradation and mechanical properties of nanocomposites based on aliphatic polyurethanes

Nanocomposites based on aliphatic polyurethanes have recently attracted a lot of attention regarding economical and ecological aspects, due to their improved thermal and mechanical properties. The aim of this paper was to investigate the influence of silica nanoparticles, differing in size and specific surface, on thermal stability and degradation, lifetime and mechanical characteristics of the obtained nanocomposites. Two series of nanocomposites based on aliphatic polyurethanes were obtained by using a single-step procedure and by addition of silica nanoparticles of types A380 or N999 at different loadings (0,0 0.15, 0.5, 1,0 and 3.5 wt.%). It was found that the increase in heating rate caused shifting of the onset temperature to higher values (from 283 to 312 ?C). According to the shape of DTG curves, it was observed that the degradation mechanism of prepared nanocomposites consists of two overlapping processes, related to the scission of hard and soft building blocks. Based on DTG results, the addition of larger N999 silica nanoparticles induced lower thermal degradation, shifting the maximum rate temperatures of the first and second degradation stages to lower values, and caused the change in the degradation mechanism. Addition of smaller silica nanoparticles (A380) did not significantly affect the mechanism of the degradation reaction, indicating homogeneity of the obtained nanocomposites. The presence of A380 nanoparticles improved thermal stability of nanocomposites, by increasing the onset temperature from 286 ?C for the pristine elastomer to 303 ?C for the sample containing 3.5 wt.% of silica. Existence of interactions of A380 silica nanoparticles with hard and soft phases was observed, based on the increase in the maximum rates of the first and second degradation steps. The activation energy of thermal degradation of polyurethanes modified with A380 silica nanoparticles was obtained by using the Flyn-Wall and Toop models. Dependence of the activation energy and the lifetime of nanocomposites based on aliphatic polyurethanes on the silica content were estimated. The highest Ea values (determined for 1 and 5 % weight loss) were found for nanocomposites containing 0.5 and 0.15 wt. % of A380 silica nanoparticles (121 and 161.2 kJ/mol). A negative effect of the silica addition on mechanical properties of nanocomposites was observed. The polyurethanes containing smaller SiO2 particles (A380) had a higher tensile strength, elongation at break and hardness as compared to the elastomers filled with larger silica nanoparticles (N999).

Effect of Durable Superhydrophobic FS/PS Using DCTES on Carbon Steel

Durable superhydrophobic surface on metal substrates was fabricated using very applicable method. The fabrication method aimed to decrease surface free energy and increase surface roughness at same time the process have been accomplished via the addition of silica nano particles with Dodecyltrimethoxysilane (DCTES) bonded to the surface of the silica particles. Adhesive polystyrene was added to improve bond between substrate and functionalized silica. The method is cheap, promising to be applied in factories heat exchangers to reduce fouling and corrosion on the large industrial scale. Scanning electron microscopy (SEM) was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88°) to superhydrophobicity (water contact angle 165.2°), while sliding contact angles dramatically decreased (<4°) by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS) and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution.

Development of a PCL-silica nanoparticles composite membrane for Guided Bone Regeneration

The pivotal step in Guided Bone Regeneration (GBR) therapy is the insertion of a membrane for support and barrier functions. Here, we studied the effect of the addition of silica nanoparticles (Si-NPs) in electrospun poly(ε-caprolactone) (PCL) membranes to improve the mechanical and osteoconductive properties of the membranes. To this end, Si-NPs were firstly synthesized and then suspended in PCL solutions containing a polar solvent (2,2,2-trifluroethanol) and water with the addition of an anionic surfactant. Nanocomposite membranes were fabricated from the solutions through an electrospinning technique. Morphology, structure and chemical composition, and tensile properties of the membranes were analyzed. Membrane stability was determined by visual examination of the membranes after immersion in phosphate buffered saline. The effect of the materials on osteoblastic differentiation was evaluated by in vitro culture of the membranes with MC3T3-E1 osteoblastic cells. The results indicated that Si-NPs were successfully incorporated in the interior of the PCL electrospun fibers during the electrospinning process. Tensile modulus was significantly increased for composition S50 and tensile strength significantly increased for compositions S25 and S50. Membranes containing Si-NPs have shown to be cytocompatible. The results obtained demonstrate that the Si-NPs were homogeneously incorporated in the electrospun fibers, resulting in an improvement of the tensile properties of the prepared materials.