Surface Treatment Of Nanoparticles Research Articles

Pathways to Green Perspectives: Production and Characterization of Polylactide (PLA) Nanocomposites Filled with Superparamagnetic Magnetite Nanoparticles.

In the category of biopolymers, polylactide or polylactic acid (PLA) is one of the most promising candidates considered for future developments, as it is not only biodegradable under industrial composting conditions, but it is produced from renewable natural resources. The modification of PLA through the addition of nanofillers is considered as a modern approach to improve its main characteristic features (mechanical, thermal, barrier, etc.) and to obtain specific end-use properties. Iron oxide nanoparticles (NPs) of low dimension (10–20 nm) such as magnetite (Fe3O4), exhibit strong magnetization in magnetic field, are biocompatible and show low toxicity, and can be considered in the production of polymer nanocomposites requiring superparamagnetic properties. Accordingly, PLA was mixed by melt-compounding with 4–16 wt.% magnetite NPs. Surface treatment of NPs with a reactive polymethylhydrogensiloxane (MHX) was investigated to render the nanofiller water repellent, less sensitive to moisture and to reduce the catalytic effects at high temperature of iron (from magnetite) on PLA macromolecular chains. The characterization of nanocomposites was focused on the differences of the rheology and morphology, modification, and improvements in the thermal properties using surface treated NPs, while the superparamagnetic behavior was confirmed by VSM (vibrating sample magnetometer) measurements. The PLA−magnetite nanocomposites had strong magnetization properties at low magnetic field (values close to 70% of Mmax at H = 0.2 T), while the maximum magnetic signal (Mmax) was mainly determined by the loading of the nanofiller, without any significant differences linked to the surface treatment of MNPs. These bionanocomposites showing superparamagnetic properties, close to zero magnetic remanence, and coercivity, can be further produced at a larger scale by melt-compounding and can be designed for special end-use applications, going from biomedical to technical areas.

Effect of regular and core shell nanoparticles on tuning the electrical properties of polypropylene for high voltage insulation

This research investigates the effect of the addition of regular titanium dioxide (TiO2) and core-shell titanium dioxide coated with Silicon dioxide (TiO2@SiO2) nanoparticles for tailoring the electrical properties of polypropylene (PP) nanocomposites. Nanoparticles with and without surface treatment were added into PP through the solution blending method. Sixteen different compositions were formulated by varying types, concentrations, and surface treatment of nanoparticles. Nanocomposites were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, AC, DC breakdown tests, leakage current, and volume resistivity. The addition of both, regular and core-shell nanoparticles, significantly improved the electrical properties of PP. It was also observed that core-shell nanoparticles revealed better electrical properties as compared to regular nanoparticles. Nanoparticles with surface treatment exhibit superior results as compared to those without treatment. This is because of the lower surface energy of surface-treated nanoparticles causing a uniform dispersion inside the polymer base.

Quantitative evaluation of nanoparticle dispersion based on modeling methods and image analysis: A case study on nano‐Sb2O3 filled Poly (butylene terephthalate) composites

AbstractThe dispersion state of filler in polymer‐matrix composites plays a significant role in determining the performance of nanocomposites. Thus, the quantification of dispersion analysis for inclusions in polymer composites is crucial. In this paper, the robust methods for the quantitative assessment of dispersion are developed. The methods are based on the modeling evaluation and direct analysis of scanning electron microscopy micrographs using binary image technology. The dispersion degree in polymer nanocomposites reinforced with inorganic nanoparticles is calculated by modeling method. In addition, the effect of dispersion on the tensile modulus of nanocomposites is analyzed by modeling method. To further quantify the dispersion of nanoparticles, the mean distance value between nanoparticles is measured. The dispersion index D is defined as the probability of inclusion particles free‐path spacing, according to the frequency distribution of particle spacing data. The dispersion states of different samples are compared to examine the availability of the analysis methods to various dispersion conditions such as the effect of aggregation, agglomeration, cluster distribution, and surface treatment of nanoparticles. Besides, another modeling methodology is established based on inter‐particle distance of the nanocomposites. In this model, the dispersion of the nanoparticles is assessed by comparing the inter‐particle distance with the theoretical value assuming a perfect dispersion. In the case of nano‐Sb2O3 filled Poly (butylene terephthalate) composites, the composites with different dispersion and distribution characteristics were prepared. And the microstructures of these composites are also employed to access the applicability and functionality of the analysis methods.

Effects of surface modification of Nano-SiO2 imbedded in organic matrix on interfacial accumulation of water molecules: an atomistic simulation study

Silica nanoparticles are used as additives to organic coatings to modify their properties. The interface of inorganic nanoparticles with an organic matrix can be a preferred location for accumulation of water. Surface treatment of nanoparticles with 3-glycidoxypropyltrimethylsilane (silane) is one way to reduce the water accumulation. In this work, using atomistic simulations (MD), we studied the effects of silane treatment on accumulation of water at the interface of nanoparticles. Three different epoxy phases and two methods of deposition of water were simulated. Water molecules were studied at two locations: (i) the interface of nanoparticles, and (ii) in the matrix of coatings. Additionally, the changes in the organic matrix due to surface treatment of nanoparticles were studied. The simulations show how silane treatment affects the interactions of water with nanoparticles in different epoxies, and also how silane treatment reduces the water accumulation in an organic matrix with nanoparticles.

Iron nanoparticle surface treatment of carbon nanotubes to increase fatigue strength of steel composites

A simple, scalable, and reproducible method is used to decorate carbon nanotubes (CNTs) with metal nanoparticles (NPs). Decorating CNTs with iron NPs prior to forming steel-based metal matrix composites (MMCs) improves the high-cycle fatigue (HCF) strength of the MMC by more than 350% vs. plain 1084 steel and more than 100% vs. an MMC with untreated CNTs. An inverse correlation between CNT loading and tensile strength was observed. The CNT surface treatment uses an organic microenvironment surrounding suspended CNTs and emulsion chemistry to treat individual CNTs or small bundles. This process can be adapted to work with other metal NPs or CNT types. This work demonstrates the potential for metal-treated CNTs to further improve the HCF strength of MMCs and paves a pathway toward additional CNT-reinforced composites.

Influence of metakaolin additive and nanoparticle surface treatment on the durability of white cement based concrete

This article is focused on the durability of white cement-based concrete treated with a nanoparticle coating developed for the production of facade panels. The mixtures under study were modified by the addition of metakaolin, which was applied as a cement replacement up to 22.5%. Metakaolin was used to increase primary resistance of the concrete to impacts from the environment. Final properties were investigated by means of compressive strength, chloride migration test, initial surface absorption test, and frost resistance. The efficiency of the surface treatment was evaluated in terms of transport properties and changes after the temperature cycling. The performed experimental program confirmed a positive influence of metakaolin addition in terms of all studied parameters; however, 15% replacement can be assumed as an optimum. The nanoparticle treatment contributed significantly to the mitigation of transport properties of the concrete mixtures. Nevertheless, cyclic temperature loading slightly reduced its tightness; local water and also chloride ions ingress was recorded. The experiments confirmed the strong potential for additional surface treatment based on the nanotechnology, but also accented the necessity of including tasks of long-term durability and primary resistance of concrete to the entire design of the structural elements.

Development of tuned refractive-index nanocomposites to fabricate nanoimprinted optical devices

The objective of this research is to demonstrate high-quality nanocomposites enabling convenient imprinting of nanopatterned optical devices. The nanocomposite developed contains homogeneously dispersed silicon (Si) nanoparticles in a UV-curable prepolymer host medium. Using an optical adhesive NOA73 as host eliminates surface treatment of the silicone mold due to minimal adhesion between the polymer and mold. Moreover, the chosen materials exhibit low shrinkage, enabling faithful replication of the master templates. Tunable refractive index is realized by mixtures of the host polymer with a refractive index of ~1.56 and nanoparticles with a refractive index of ~3.45. For example, using a ~28% Si fraction, an imprintable material with a refractive index of ~2.1 results. Surface functionalization of nanoparticles with polyvinylpyrolidone is shown to reduce agglomeration. Dynamic light scattering (DLS) and Fourier-transform infrared (FTIR) spectroscopy are employed to investigate the stability of nanocomposites and the efficacy of the surface treatment of nanoparticles, respectively. The quality and physical parameters of the fabricated devices are evaluated by the atomic force microscopy (AFM) and scanning electron microscopy (SEM). The thickness of a homogeneous sublayer underneath a periodic layer in the fabricated optical devices is controlled by employing a channel with precisely managed depth. The example resonant filters show acceptable response as measured in the 1600-1800 nm spectral band and reasonable agreement with theoretical predictions.

Fluorescence quenching of APTES by Fe2O3 nanoparticles – Sensor and antibacterial applications

Fe2O3 nanoparticles are particularly attractive for sensor and drug delivery applications because of their size-dependent super paramagnetism, low toxicity, and biocompatibility with cells and tissues. Binding interaction studies of 3-aminopropyltriethoxysilane (APTES) with Fe2O3 nanocrystals have been carried out by absorption, fluorescence, dispersion, SEM, TEM, AFM and FT-IR spectral studies. APTES act as a new host for Fe2O3 nanocrystals that quenches its fluorescence due to the electron transfer of APTES. It adsorbs on the surface of the Fe2O3 nanoparticles. Dispersion studies, SEM and FT-IR confirm the adsorption of APTES on the surface of Fe2O3 nanocrystals. Fe2O3 nanocrystals quench the fluorescence of APTES. Surface treatment of nanoparticles by APTES and its mechanism discussed in detail. Antibacterial test such as well-cut diffusion have been done in agar plates using 100μL concentration of functionalised and non-functionalised Fe2O3 nanoparticles. Functionalised Fe2O3 nanoparticles show enhanced biocidal activity when compared with non-functionalised Fe2O3 nanoparticles in repeated experiments.

Effects of surface morphology and treatment of iron oxide nanoparticles on the mechanical properties of an epoxy coating

Abstract Iron oxide nanoparticles with fiber-like and polygon morphologies were synthesized in the presence of triethanolamine and urea surfactants. The synthesized particles were then treated by 3-amino propyl trimethoxy silane (APTMS). Then, the nanocomposites were prepared through incorporation of 1 wt.% unmodified and surface modified nanopigments into the epoxy resin. The phase composition and morphology of the nanoparticles were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM), respectively. The chemical grafting of silane chains on the surface of nanoparticles was studied by Fourier transform infrared spectroscopy (FT-IR). The mechanical properties and fracture morphology of the nanocomposites were investigated by tensile test. SEM and XRD analyses revealed that surfactants significantly affected the size and morphology of the nanopigments. FT-IR analysis confirmed chemical functionalization of APTMS chains on the surface of nanopigments. It was found that surface treatment of nanoparticles by APTMS effectively improved the compatibility and dispersion of particles in the epoxy matrix. The nanoparticle synthesized in the presence of urea increased the fracture toughness and tensile strength of the composite greater than the nanopigment synthesized in the presence of triethanolamine. Results obtained from tensile test revealed the noticeable improvement of the interfacial interactions between Fe 3 O 4 /APTMS particle and epoxy matrix. Inclusion of surface modified nanopigments into the epoxy coating resulted in higher tensile strength and fracture toughness compared to the coating filled with unmodified nanopigments. It was found that the morphology and surface chemistry of the nanopigment significantly affected the mechanical properties of the epoxy coating.

Switch-On fluorescence and photo-induced electron transfer of 3-aminopropyltriethoxysilane to ZnO: Dual applications in sensors and antibacterial activity

Binding interaction studies of 3-aminopropyltriethoxysilane (APTS) with sol–gel synthesized ZnO nanocrystals have been carried out by absorption and fluorescence spectral studies. Astonishing consequences have been observed due to electron transfer from APTS to sol–gel synthesized ZnO. APTS acts as a new host for sol–gel synthesized ZnO nanocrystals that augment its fluorescence due to the electron transfer. APTS adsorbs on the surface of the ZnO nanoparticles. Dispersion studies, SEM and FT-IR confirm the adsorption of APTS on the surface of ZnO nanocrystals. Surface treatment of nanoparticles by the fluorophore APTS and its mechanism are discussed in detail. Bacteriological tests such as disk diffusion have been done in nutrient agar media on solid agar plates using different concentrations of ZnO. f-ZnO nanoparticles show remarkable biocidal activity when compared with n-ZnO in repeated experiments.

The Effect of surface Treatment of Alumina NanoParticles with a Silane Coupling Agent on the Mechanical Properties of Polymer Nanocomposites

Surface-treated and untreated alumina nanoparticles were mixed with a polycarbonate matrix at different weight percentages and the mechanical properties of the nanocomposites produced were determined by subjecting them to quasi-static tension and Charpy impact tests. The results obtained showed that the surface treatment of nanoparticles had improved their mechanical properties.

Effect of pre-treatment of nanofillers on the dielectric properties of epoxy nanocomposites

Early researches show that the nano filler dispersion has a significant effect on the dielectric properties of resulting epoxy nanocomposites. In this paper a comparative study on the dielectric permittivity, AC breakdown behaviours and glass transition temperature of epoxy nanocomposites loaded with both treated and untreated nano SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> fillers has been carried out. The epoxy resin (LY556), commonly used in power apparatus, was used to study the dielectric behaviour of epoxy. Silane was used as a coupling agent to pre-treat the nano particles. The results indicate that the surface treatment of nanoparticles has a strong effect on the dielectric properties of resulting nanocomposites as surface treated nanoparticles with better dispersions is believed to hinder the polymer chain mobility and charge transportation through the interface region between epoxy and nanoparticles .

Photo-initiated chemical vapor deposition as a scalable particle functionalization technology (a practical review)

Chemical vapor deposition (CVD), and its variants, is a more viable technology than the addition of surface active agents to modify nanoparticle surfaces. While thermally-activated CVD simply works by initiating the monomers using heat, some other techniques are more powerful and versatile. Indeed, higher energy CVD methods open up possibilities to a wider range of monomers. Unfortunately, different terminologies and classifications due to parallel work have led to confusion. This paper presents and explains the different techniques as well as their equivalent terminologies to clarify the big picture. While the demand for functionalized nanoparticles grows rapidly, current functionalization methods are still too expensive for most applications. This paper is intended to be a practical review of the gas phase methods available in order to identify a potential candidate for large scale functionalization of nanoparticles. This study identifies photo-initiated CVD (PICVD) as an ideal solution for scalable particle functionalization technology. This paper is intended to be a practical review of the gas phase methods available in order to identify a potential candidate for large-scale functionalization of nanoparticles. The focus is put on photo-initiated CVD (PICVD) as an ideal solution for scalable particle functionalization technology. ► Review of gas-phase nanoparticle surface treatment technologies ► Ranking based on technique scalability and versatility ► Equivalence between existing terminologies and proposal of a common terminology ► Identification of avenues of research for one promising technique: PICVD

Tuning electric bistability in pentacene film-based transistor embedding aluminum nanoparticles

Hybrid films of pentacene and aluminum nanoparticles were prepared by depositing pentacene on a SiO2 surface decorated with aluminum nanoparticles and used as the active channel materials in a thin film transistor. Surface pre-treatment of the aluminum nanoparticles with oxygen plasma and/or organophosphonic acids render the particles surface with different coatings and work functions, which affect the charge trapping/storing ability of the nanoparticles. This in turn results in an electric bistability of the pentacene film-based transistor/memory devices. Correlations of memory window, switching response, and memory retention characteristics with the aluminum nanoparticle surface treatment are provided.

Effect of nanoparticle surface treatment on morphology, electrical and water treeing behavior of LLDPE composites

This paper reports on the role of silica nanoparticle surface treatment in affecting the morphology, charging current, frequency dependence of dielectric parameters, breakdown electric field and water treeing behaviors of linear low density polyethylene (LLDPE). Octyl-trimethoxysilane was used as a silane coupling agent for the surface treatment of the silica nanoparticles. The composite sample with silane-treated nanoparticles shows improved dielectric properties when compared with the sample with unsurface-treated nanoparticles. However, although both types of silica nanoparticles show apparent water tree resistance in LLDPE, the sample with unsurface-treated nanoparticles shows shorter water tree length.

Surface tailoring of SiO 2 nanoparticles by mechanochemical method based on simple milling

An appropriate modifying agent is obviously important with regard to the surface treatment of nanoparticles. Moreover, a right physical mixer that can provide enough energy to break up the secondary structure (aggregate and agglomerate) of nanoparticles is absolutely critical to the modification as well. However, it is not easy to give consideration to both of them during the process of modification. As is often the case, we tend to take care of the modifying agent but lose sight of the physical mixer. In this paper, hybrid particles of SiO 2/2,4-Diisocyanatotoluene (SiO 2/TDI) and SiO 2/2,4-Diisocyanatotoluene/hydroxyl silicone oil (SiO 2/TDI/(PDMS-OH)) were fabricated by mechanochemical method based on simple milling. The prepared hybrid particles (SiO 2/TDI and SiO 2/TDI/(PDMS-OH)) were characterized by infrared spectroscopy (FT-IR), static contact angle (CA), water sorption measurement, thermal analysis (TGA and DSC) and transmission electron microscopy (TEM). FT-IR spectra and thermal analysis (DSC) results demonstrate that TDI together with PDMS-OH is chemically anchored to the surface of nano-SiO 2. TGA results show that the grafting density of TDI is as high as 2.62 TDI/nm 2, while the grafting density of PDMS-OH is 0.0156 PDMS-OH/nm 2. Deduced from static contact angle (CA) and water sorption measurement, both hybrid particles exhibit strong hydrophobic (140 o for SiO 2/TDI and 144 o for SiO 2/TDI/(PDMS-OH)) after modification. TEM images reveal that hybrid particles (SiO 2/TDI and SiO 2/TDI/(PDMS-OH)) prepared by ball milling method exhibit much better miscibility and dispersibility in PDMS matrix when compared with those particles prepared by a common mixing device.

Purposeful surface treatment of nanoparticles for tuning structure and properties of polymer based nanocomposites

intense industrial and academic research for the past twenty years. As viewed from literature, however, the properties of nanocomposites are sometimes not significantly improved or even worse than those of the matrices. This used to result from direct incorporation of nano-scale building blocks into polymers. Because of the strong tendency of nanoparticles to agglomerate, nano-size fillers are hard to be uniformly dispersed in polymers by conventional techniques. In this context, surface modification of the nano-fillers, that is able to increase hydrophobicity of the inorganic fillers, enhance interfacial adhesion via physical interaction or chemical bonding, and eliminate the loose structure of filler agglomerates, should be a key issue. Comparatively, the achievements in modern chemistry (incl. grafting techniques, click chemistry, non-covalent bonding, etc.) are much more prominent than those in compounding techniques. Therefore, there are enormous possibilities for modifying nanoparticles. The combination of different surface treatment methods with existing mixing machines would generate nanocomposites with tailor-made structure and performance and enrich the measures of nanocomposites manufacturing. In general, homogeneous dispersion of the fillers is considered to be the main concern, but in fact, it can not guarantee good properties of the nanocomposites. In addition to the dispersion, filler/matrix interaction and filler/filler interaction exert critical influence on the composites properties. A proper surface functionalization approach should take account of all these issues and eventually leads to the optimal microstructure with the help of carefully designed processing parameters. Naturally, a problem has arisen: what is the desired arrangement of the nanoparticles in matrix according to different properties requirements? So far, theoretical consideration of the mechanisms involved in nanocomposites with adequate predictability is relatively less reported. Design and production of polymer nanocomposites have to be mostly conducted on a trial and error basis. Empirical extrapolation of the parameters related to components selection and processing technique is not very successful. On the basis of analysis hereinbefore, it can be concluded that one has to firstly have a clear image of the proposed nanocomposites and the microstructure, and then start to work out a feasible route of surface treatment of nanoparticles and the way of compounding. The importance of each step mentioned above should be equally considered.

A route to wear resistant PTFE via trace loadings of functionalized nanofillers

A fluorosilane nanoparticle surface treatment of alumina nanoparticles was studied to test a hypothesis that reduced surface energy would improve dispersion and extend wear resistance of polytetrafluoroethylene (PTFE) to trace nanoparticle loadings. Dry sliding wear tests were performed on PTFE nanocomposites with 0.00, 0.13, 0.50 and 1.00% untreated and treated 40 nm α phase alumina nanoparticles. The untreated alumina reduced the wear of PTFE by 10–100× at 0.13% loading with variability typical of lightly loaded PTFE nanocomposites. The treated nanoparticles reduced the wear of PTFE by 6000× at 0.13% loading and demonstrated no evidence of variability; wear was improved 6000–10,000× with 0.13–1% nanoparticle loading. AFM morphology studies revealed that the α phase alumina nanoparticles altered the PTFE morphology. Correlation between PTFE wear resistance and morphology was demonstrated as far less effective δ:γ phase alumina had no appreciable effect on PTFE morphology. During TEM dispersion characterization, the untreated nanoparticles were found primarily in clusters while treated nanoparticles were found individually dispersed. It is believed that the surface properties of the α phase particles induce a wear resistant PTFE morphology, while the fluorosilane treatment facilitated dispersion and extended the beneficial effects of the nanoparticles to significantly lower loadings.

Transparent poly(bisphenol A carbonate)-based nanocomposites with high refractive index nanoparticles

Transparent organic–inorganic nanocomposites were successfully synthesized from sulfonic acid-modified poly(bisphenol A carbonate) (SPC) and TiO 2 or ZrO 2 nanoparticles. The dispersibility of nanoparticles was significantly improved by both the surface treatment of nanoparticles with phosphoric acid 2-ethylhexyl esters (PAEH) and the introduction of a sulfonic acid moiety into the PC chain. It was found that in some cases, crystallization of the matrix caused a reduction in transparency. Efficient dispersion of nanoparticles and the absence of crystallization resulted in highly transparent nanocomposites with up to 42 wt% TiO 2 and 50 wt% ZrO 2 nanoparticles. The refractive indices of the nanocomposites based on SPC increased with the increasing amount of nanoparticles. Theoretical equation based on Maxwell–Garnett effective medium theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The prepared nanocomposites had lower thermal stability than the host matrix polymers.

Effects of nanoparticle treatment and compatibilizers on the properties of (PP/EPR)/nano-CaCO3 blends

Effects of nanoparticle surface treatment and compatibilizers (PEP and EPR-g-MAH) on the mechanical behavior, rheological and morphological properties of (PP/EPR)/CaCO3 blends were investigated by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Blends of various compositions (with and without compatibilizer and nanoparticles) were prepared using a corotating twin-screw extruder. The results demonstrated that the dispersion of nano-CaCO3 depends on surface-treating agent (Stearic acid or Fatty acids). The presence of the nanoparticles and the compatibilizers does not modify significantly thermal and rheological properties. But, EPR-g-MAH copolymer seems to modify the interface between PP and EPR phases and increase the size of EPR particles. The study of mechanical properties (tensile and impact tests) shows the presence of compatibilizers in (PP/EPR) blends; especially PEP significantly increases the deformation and the energy at break. But the reduction of the elongation at break and the impact strength respectively of 7 and 30% seems to be due to lower adhesion between the nanoparticles and the (PP/EPR) matrix.