Untreated SiO2 Research Articles

Double layer chemical encapsulation of SiO2 nanoparticles for interfacial tension reduction under low salinity condition

Recently, rapid growth ofnanotechnologyhas accelerated immensely, and has provided adequate scientific evidence supporting nanoparticles (NPs) as revolutionary agents for oil reservoirs, particularly, for interfacial tension reduction (IFT). For this reason, this paper present synthesis, characterization, and IFT evaluation of new double layer encapsulated SiO2 NPs. The synthesis has been initiated via precursor polyacrylic acid (PAA) to form a first layer intermediate product (SiO2-g-PAA). Subsequently, the SiO2-g-PAA was then individually condensed with Xanthan polymer and 3-aminopropyltriethoxysilane (KH550), to establish double layer products; SiO2-g-PAA-Xanthan and SiO2-g-PAA-KH550, respectively. The products were characterized using Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and X-ray Diffraction (XRD). Spinning Drop equipment was used to assess the nanofluid’s IFT reduction effects at 0.01, 0.03 & 0.05 % in low salinity (0.3 % NaCl) by comparing with the baseline brine IFT. The FTIR results have confirmed the syntheses of the products, while the FESEM micrographs have described the surface morphologies and average particle size within the nanoscale (36 nm for SiO2-g-PAA-Xanthan & 61 nm for SiO2-g-PAA-KH550). Interestingly, the XRD patterns of all the grafted NPs exhibit amorphous behaviours at 20 θ similar to pure SiO2. The IFT investigations revealed that the brine/oil baseline IFT was recorded to be 9.9 ± 0.07 mN/m, however, upon introducing pure SiO2 NPs into the system at 0.01, 0.03 and 0.05 %, the IFT reduced to a range of 6–8 mN/m (20–33 % efficiency). However, in the presence of SiO2-g-PAA-KH550, extraordinary reduction of the IFT was achieved to a range of 0.5–0.7 mN/m with significant reduction efficiency up to 94 % with respect to a baseline IFT. This is due to the terminal PAA-KH550 on the surface of the SiO2. However, in the case of terminal PAA-xanthan in the SiO2-g-PAA-Xanthan, the polymer did not influence the IFT remarkably, with the IFT reduction efficiency even far lower than the untreated SiO2. Thus, a grafted double layer NPs containing a terminal PAA-KH550 could be an ideal candidate for potential application in chemical EOR due to a remarkable demonstration of IFT reduction which is one of the preconditions governing the successful EOR operation in oil fields.

The effect of pretreatment on SiO2 for Co-based Fischer-Tropsch synthesis catalysts: a study of the reduction pathway

The reduction pathway of Co catalysts supported on untreated SiO2 along with two pretreated SiO2 support materials was investigated. In situ XRD studies clearly showed the likely reduction pathways of the cobalt oxides on the untreated SiO2, ethylene glycol pretreated SiO2, and annealing pretreated SiO2 supports. Ethylene glycol pretreated SiO2-supported Co (Co/E–SiO2) catalyst showed smaller metal crystallites, highly dispersed Co and high Co(hcp)/Co(fcc) ratio because of the high percentage of non-H-bonded silanols; however, the high percentage of the non-H-bonded silanols created a strong Co-SiO2 interaction which caused a low degree of reduction of CoO resulting in lower FT activity. In contrast, the annealing pretreated SiO2-supported Co (Co/A–SiO2) catalyst did not significantly increase the percentage of non-H-bonded silanols and Co(hcp)/Co(fcc) ratio when compared with Co/E–SiO2, but it exhibited a better catalytic activity during FTS.

A Hybrid Superhydrophobic/Hydrophilic Surface Based on SiO2 Nanoparticles over a Clay Substrate for Enhanced Dew Yield Potential

The study of SiO2 nanoparticles (NPs) and their corresponding surface modifications through octadecyltrichlorosilane (OTS) has attracted attention due to their self-cleaning, hydrophobic and superhydrophobic (SHPho) properties, which are desirable for water collection based on the dew condensation effect. Such properties have been addressed by different strategies, of which the development of hybrid superhydrophobic/hydrophilic (SHH) surfaces has shown great promise. In this research, the pairing of OTS-treated and untreated SiO2 NP layers deposited on clay substrates is investigated with the aim of exploring a hybrid SHH surface capable of enhancing dew yield behavior. Infrared analyses were conducted using FTIR to study the interaction between the clay substrate and the OTS-treated and untreated SiO2 NPs. The hybrid SHH surfaces were morphologically characterized, and contact angle (CA) measurements were performed to explore their wettability behavior. The developed hybrid SHH surfaces exhibited hydrophilic (HPhi)/SHPho properties with an improved dew yield performance. The results obtained in this article are of relevance to the development of water-harvesting devices based on hybrid SHH surfaces.

Modification of macromolecular dynamics in polyacrylic hybrid nanocomposite with un-treated SiO2 nanoparticles

The viscoelastic properties of polyacrylic/SiO2 nanocomposites were investigated; nanoparticles content varied up to 3 wt%. The results showed that the concentration of SiO2 influences both the molecular weight, as well as the thermal and mechanical properties. As-cast films show optical transparency and no evidence of macro-aggregation. The elemental mapping analysis confirmed the presence of Si throughout the films and scanning electron microscopy (SEM) show evidence of dispersed micro-aggregates at high SiO2 concentrations. Differential scanning calorimetry (DSC) and shear rheometry showed that the glass transition temperature, Tg, significantly decreased relative to neat polyacrylic, i.e., ΔTg < 0, and this effect was not associated with molecular weight. Hardness and tensile modulus decrease nearly 64% and 70% respectively relative to the neat polyacrylic. Dynamic mechanical analysis (DMA) showed higher shear elastic modulus and shift of maximum of tan δ in the polyacrylic. The results suggest a modified polymer molecular dynamics driven by interactions of the un-treated nanoSiO2 with the matrix.

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.

PLA/SiO2 composites: Influence of the filler modifications on the morphology, crystallization behavior, and mechanical properties

ABSTRACTFilms of an architecturally modified poly(lactic acid) (PLAREx) with three different types of fumed silica nanofillers (SiO2) were processed through reactive extrusion‐calendering in a pilot plant. The effects of the SiO2 type on both the dispersion and the crystallization behavior under dynamic and isothermal conditions are investigated using transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The mechanical properties are assessed by tensile testing. TEM micrographs showed that the improved chemical affinity of both surface‐treated SiO2 toward PLAREx end groups did not improve particle dispersion. DSC results revealed that untreated SiO2 nucleated PLAREx more efficiently than both surface‐modified silicas. The activation energy for the isothermal crystallization process, as determined by an Arrhenius method, suggests that addition of untreated SiO2 enhances the crystallization rate of PLAREx. However, it seems that the tensile behavior remained unchanged whether silicas were added or not. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45367.

Effects of silica on the morphology, structure, and properties of thermoplastic cassava starch/poly(vinyl alcohol) blends

ABSTRACTThermoplastic cassava starch (TPS)/poly(vinyl alcohol) (PVA)/silica (SiO2) composites were prepared by a melt‐mixing method. The effects of the content and surface properties of SiO2 on the processing, mechanical properties, thermal stability, morphology, and structure of the TPS/PVA/SiO2 composites were investigated. With increasing SiO2 content, the plasticizing times of the TPS/PVA/SiO2 composites were shortened. After the SiO2 surface was treated with a silane coupling agent (KH550), the plasticizing times of the TPS/PVA/SiO2 composites decreased significantly. The tensile strength, elongation at break, and Young's modulus of the TPS/PVA/SiO2 composites increased. The mechanical properties of the TPS/PVA/SiO2 composites containing treated SiO2 were higher than those with untreated SiO2. The thermal decomposition temperatures of the TPS/PVA/SiO2 composites were improved with the addition of SiO2. The presence of inorganic fillers was beneficial to the improvement of the thermal stability of the polymers. The reaction between the treated SiO2 and the starch molecules was beneficial to the formation of more stable structures. The treated SiO2 indicated good interfacial adhesion and uniform dispersion in the matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44020.

Acrylate hybrid nanocomposite coatings based on SiO2 nanoparticles. In-situ semi-batch emulsion polymerization

Acrylate–SiO2 nanocomposites were synthesized by in situ emulsion semi-batch polymerization in aqueous dispersion utilizing untreated nanoparticles. Butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) with composition 56:42:2 were copolymerized at 50% solids in the presence of SiO2 nanoparticles of 7nm size. SiO2 nanoparticles were added up to 3wt% and the emulsions thus obtained were stable for at least 6months in storage at room temperature. The semi-batch polymerization was carried out for 2.5h. and yielded conversions as high as 92% and not lower than 84%, superior to batch polymerization of the same system. The synthesized emulsion hybrids were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning and transmission electron microscopy and atomic force microscopy. As cast films about 1mm thick were optically transparent suggesting good nanoparticle dispersion. However, dispersed SiO2 nano aggregates were detected by SEM, TEM and AFM, and the identity of the nanoclusters was confirmed by EDS and EFTEM. Thus, the morphology of cast films consisted of SiO2 nanoclusters dispersed throughout the acrylate matrix. Strikingly, the untreated SiO2 nanoparticles induced significantly higher thermal decomposition temperatures, Tdec increased by as much as 20°C relative to the neat acrylate. There was also an increase of glass transition temperature Tg and tensile modulus increased nearly 100% relative to the neat acrylate suggesting modification of macromolecular dynamics by the presence of the SiO2 nanoparticles, and this was confirmed by shear rheometry of the molten coatings where a rubber-like plateau was clearly defined. The results are contrasted for the same system but using batch polymerization.

The effect of the addition of polypropylene-grafted SiO2 nanoparticle on the thermal conductivity of isotactic polypropylene

The thermal conductivity of Isotactic polypropylene (iPP)/silica particle (SiO2, 26 nm) nanocomposite has been investigated. The untreated SiO2 and iPP grafted onto SiO2 were dispersed in the iPP (Mw = 2.5 × 105) matrix. The molecular mass of the iPP-grafted chain, Mn, was precisely controlled to be 5.8 × 103, 1.2 × 104, and 4.6 × 104. It was found that the thermal conductivities of graft-treated nanocomposites were higher than that of untreated SiO2 composites. This implied that it is possible to achieve even higher thermal conductivity using the graft treatment. A thermal conductivity analysis conducted using a three-phase model, with considerations for thermal conductivity at interfacial layers, showed that the thermal conductivity of the interfacial layer increased significantly when a graft chain was incorporated. Moreover, the thermal conductivity per graft chain was proportional to the 1/2 power of the molecular mass (\( M_{\text{n}}^{0.5} \)). The results strongly suggest that the thermal conductivity pathway of interfacial layer was the main chain direction of iPP-grafted molecular chains.

Effect of O3 on Growth of Pt by Atomic Layer Deposition

The growth characteristics of Pt deposited by atomic layer deposition (ALD) with methylcyclopentadienyltrimethylplatinum (MeCpPtMe3) and O3 are studied both experimentally and by modeling. The growth rate of Pt ALD using O3 is higher than that using either air or O2 counter reactants. In addition, a low deposition temperature of 150 °C for the deposition of metallic Pt using O3 is obtained. To investigate the role of O3 during initial growth, Pt is deposited on O3-pretreated SiO2 using air as the counter reactant. Pt deposited in this way on O3-pretreated SiO2 shows a rapid increase of surface coverage, which is similar to Pt ALD using O3 and different from Pt ALD using air on untreated SiO2. From the modeling study, it is found that pretreating the surface with O3 increases the steady state nucleation rate and decreases the nucleation incubation time on the SiO2 surface, the same phenomena which are believed to occur during the initial growth of ALD Pt using O3 counter reactant.

Effect of reduction of trap charge carrier density in organic field effect transistors by surface treatment of dielectric layer

In this work, we have studied the effect of surface treatment of SiO2 dielectric layer on the reduction of the trap charge carrier density at dielectric/semiconducting interface by fabricating a metal–insulator–semiconductor (MIS) device using α, ω-dihexylcarbonylquaterthiophene as semiconducting layer. SiO2 dielectric layer has been treated with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) to modify the chemical group acting as charge traps. Capacitance-voltage measurements have been performed on MIS devices fabricated on SiO2 and HMDS treated SiO2. These data have been used for the calculation of trap charge carrier density and Debye length at the dielectric-semiconductor interface. The calculated trap charge carrier density has been found to reduce from (2.925 ± 0.049) × 1016 cm−3 to (2.025 ± 0.061) × 1016 cm−3 for the MIS device with HMDS treated SiO2 dielectric in comparison to that of untreated SiO2. Next, the effect of reduction in trap charge carrier density has been studied on the performance of organic field effect transistors. The improvement in the device parameters like mobility, on/off ratio, and gate leakage current has been obtained with the effect of the surface treatment. The charge carrier mobility has been improved by a factor of 2 through this treatment. Further, the influence of the treatment was observed by atomic force microscope and Fourier transform infrared spectroscopy techniques.

The correlation between gate dielectric, film growth, and charge transport in organic thin film transistors: the case of vacuum-sublimed tetracene thin films

The complex interplay of dielectric substrate properties, semiconducting film growth, crystal structure, texture, and charge carrier transport is investigated for the case of tetracene films deposited on different dielectrics (polystyrene, parylene C, polymethylmethacrylate, hexamethyldisilazane-treated SiO2, and untreated SiO2). The tetracene hole mobility, measured in the bottom-gate organic thin film transistor (OTFT) configuration, varies over more than one order of magnitude depending upon the dielectric layer used. Atomic force microscopy and synchrotron grazing incidence X-ray diffraction measurements, analyzed with the extended Rietveld method, were used to investigate the influence of film connectivity, crystalline phase, polymorphism, and texture on charge transport. The role of the surface polarity and the processing conditions of the gate dielectric layer are also discussed. Based on our results, we propose guidelines for the selection of a gate dielectric material favorable for charge transport in tetracene films.

Silica Nanoparticles Treated by Cold Atmospheric-Pressure Plasmas Improve the Dielectric Performance of Organic–Inorganic Nanocomposites

We report on the application of cold atmospheric-pressure plasmas to modify silica nanoparticles to enhance their compatibility with polymer matrices. Thermally nonequilibrium atmospheric-pressure plasma is generated by a high-voltage radio frequency power source operated in the capacitively coupled mode with helium as the working gas. Compared to the pure polymer and the polymer nanocomposites with untreated SiO(2), the plasma-treated SiO(2)-polymer nanocomposites show higher dielectric breakdown strength and extended endurance under a constant electrical stress. These improvements are attributed to the stronger interactions between the SiO(2) nanoparticles and the surrounding polymer matrix after the plasma treatment. Our method is generic and can be used in the production of high-performance organic-inorganic functional nanocomposites.

Lattice-patterned LC-polymer composites containing various nanoparticles as additives.

In this study, we show the effect of various nanoparticle additives on phase separation behavior of a lattice-patterned liquid crystal [LC]-polymer composite system and on interfacial properties between the LC and polymer. Lattice-patterned LC-polymer composites were fabricated by exposing to UV light a mixture of a prepolymer, an LC, and SiO2 nanoparticles positioned under a patterned photomask. This resulted in the formation of an LC and prepolymer region through phase separation. We found that the incorporation of SiO2 nanoparticles significantly affected the electro-optical properties of the lattice-patterned LC-polymer composites. This effect is a fundamental characteristic of flexible displays. The electro-optical properties depend on the size and surface functional groups of the SiO2 nanoparticles. Compared with untreated pristine SiO2 nanoparticles, which adversely affect the performance of LC molecules surrounded by polymer walls, SiO2 nanoparticles with surface functional groups were found to improve the electro-optical properties of the lattice-patterned LC-polymer composites by increasing the quantity of SiO2 nanoparticles. The surface functional groups of the SiO2 nanoparticles were closely related to the distribution of SiO2 nanoparticles in the LC-polymer composites, and they influenced the electro-optical properties of the LC molecules. It is clear from our work that the introduction of nanoparticles into a lattice-patterned LC-polymer composite provides a method for controlling and improving the composite's electro-optical properties. This technique can be used to produce flexible substrates for various flexible electronic devices.

Effects of Ar plasma treatment for deposition of ruthenium film by remote plasma atomic layer deposition

Ruthenium thin films were deposited on argon plasma-treated SiO2 and untreated SiO2 substrates by remote plasma atomic layer deposition using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a Ru precursor and ammonia plasma as a reactant. The results of in situ Auger electron spectroscopy (AES) analysis indicate that the initial transient region of Ru deposition was decreased by Ar plasma treatment at 400 °C, but did not change significantly at 300 °C. The deposition rate exhibited linearity after continuous film formation and the deposition rates were about 1.7 Å/cycle and 0.4 Å/cycle at 400 °C and 300 °C, respectively. Changes of surface energy and polar and dispersive components were measured by the sessile drop test. The quantity of surface amine groups was measured from the surface nitrogen concentration with AES. Furthermore, the Ar plasma-treated SiO2 contained more amine groups and less hydroxyl groups on the surface than on untreated SiO2. Auger spectra exhibited chemical shifts by Ru-O bonding, and larger shifts were observed on untreated substrates due to the strong adhesion of Ru films.

Interface properties of OFETs based on an air‐stable n‐channel perylene tetracarboxylic diimide semiconductor

AbstractIn this study, several experimental techniques were employed to gain insights into the molecular interactions at the interfaces in organic field‐effect transistors (OFETs). A self‐assembled monolayer (SAM) was applied to the gate insulator to influence the interactions at the interface. Macroscopic electrical measurements, microscopic potentiometry, absorption/luminescence spectroscopy, and ellipsometry are combined to study top‐contact OFETs based on an air‐stable n‐channel perylene derivative. They show clearly the advantage and capability of local electrical investigations compared to DC electrical characterization. The DC electrical measurements provide an improvement of the electron mobilities within the channel and unchanged contact resistances (within the error bars). Only the potentiometry allowed a deeper insight: It reveals a small decrease of the source contact resistance and a drain bias dependence of the mobility, which decreases due to prior hydrophobization of the SiO2 gate insulator. This is attributed to different charge carrier trap concentrations and injection barriers in the organic semiconductor near the dielectric interface caused by diffused water which is discussed in detail. The optical absorption/luminescence spectroscopy and ellipsometry indicate an unchanged ordered molecular arrangement with a molecular tilt angle of (33 ± 4)° with respect to the dielectric surface and rather weak intermolecular interaction for the devices with treated and untreated SiO2.

The properties of Ru films deposited by remote plasma atomic layer deposition on Ar plasma‐treated SiO2

AbstractBy using remote plasma atomic layer deposition (ALD), ruthenium thin films were deposited on SiO2 using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a Ru precursor and an ammonia plasma as a reactant. Different plasma treatments were applied, and the best results were obtained with the Ar plasma‐treated SiO2 surface. The initial transition region usually observed with Ru deposition before continuous film formation was present, and the number of ALD cycles required to obtain a continuous film was reduced to about 35 cycles on the Ar plasma‐treated SiO2 substrates. The transition region of Ru cluster growth on Ar plasma‐treated SiO2 was investigated with transmission electron microscopy (TEM). Most of the Ru clusters were larger and better crystallized on the Ar plasma‐treated SiO2 than on untreated SiO2. Also, Ru films deposited on the treated SiO2 exhibited a (002) preferred orientated structure with a film resistivity of about 10.26 µΩ‐cm. The growth rates of Ru after passing the transition region were similar on both the treated and untreated SiO2 at about 1.7 Å/cycles. From the Auger electron spectroscopy (AES) spectrum, a very low content of oxygen was observed in the Ru films. About 9% carbon was detected by a rutherford backscattering spectrometer (RBS).

Dispersion stability and rheological behavior of suspensions of polystyrene coated fumed silica particles in polystyrene solutions

Polystyrene coated silica (SiO2@PS) core-shell composite particles with averaged diameter of about 290 nm were prepared by in situ emulsion polymerization of styrene on the surface of γ-methacryloxypropyltrimethoxysilane grafted SiO2 nanoparticles of 20–50 nm in diameter. Rheological behavior and dispersion stability of SiO2@PS suspension in 10 wt% PS solution were compared with suspensions of untreated SiO2 and silane modified SiO2 nanoparticles. Suspensions of the untreated and the silane modified SiO2 exhibited obvious shear thinning. The SiO2@PS suspension exhibits shear viscosity considerably smaller than suspensions of untreated and silane modified SiO2 at low shear rates. Transmission electron microscopy showed that the composite particles can uniformly and stably disperse in PS solution compared to other suspensions, implying that the PS shell can effectively enhance the particle compatibility with PS macromolecules in solution.

Synthesis, morphology, and field-effect transistor characteristics of new crystalline-crystalline diblock copolymers of poly(3-hexylthiophene-block -steryl acrylate)

We report the synthesis, morphology, and charge-transporting characteristics of new crystalline–crystalline diblock copolymers, poly(3-hexylthiophene-block-stearyl acrylate) (P3HT-b-PSA). Three different diblock copolymers, P1, P2, and P3, with P3HT/PSA polymerization degree block ratios of 60/26, 60/50, and 60/360, respectively, were prepared for investigating the morphology-property relationship and the dependence of optoelectronic properties on the block copolymer structure. Small- and wide-angle X-ray scattering indicated the presence of both P3HT and PSA crystalline domains and the presence of microphase separation among blocks. The transmission electron microscopy and atomic force microscopy results revealed that the diblock copolymers cast from chlorobenzene, tended to form needle-like morphologies. The field-effect mobilities of the diblock copolymers deposited on untreated SiO2 substrates, decreased with increasing PSA block length. In a sharp contrast, the mobilities enhanced with increasing PSA content when the P3HT-b-PSA was deposited on phenyltrichlorosilane (PTS)-treated substrates. The copolymers with a 60/360 P3HT/PSA ratio showed a good mobility of 4 × 10−3 cm2 V−1 s−1 and a high on/off ratio of 7 × 106 on PTS-treated substrates. This study highlighted the importance of the block ratio, the substrate and self-assembly structures on the charge transport characteristics of the crystalline–crystalline conjugated diblock copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Polypropylene/SiO2 nanocomposites filled with different nanosilicas: thermal and mechanical properties, morphology and interphase characterization

Untreated and surface-treated SiO2 nanoparticles with different alkyl chain length (described as C0, 3C1, C8 and C16 according to the number of carbon atoms) on particle surface were used as fillers for isotactic polypropylene (iPP). The iPP/SiO2 composites containing 2.3 vol% of nanoparticles were prepared by melt blending and injection moulding. The dispersion quality of nanoparticles in matrix was examined using scanning electron microscopy (SEM). The crystallization behaviour of iPP was examined using differential scanning calorimetry (DSC). The mechanical properties of all samples were characterized by tensile test, compact tension (CT) test and dynamic mechanical thermal analysis (DMTA). The particle–matrix interphase behaviour was also examined and discussed. SEM images show that different silicas show different dispersion quality in matrix due to different hydrophobicity. The crystallinity and spherulite size of matrix are overall decreased in composites. The tensile properties of iPP/SiO2 composites show clear relationship with alkyl chain length on particle surface, i.e. increasing alkyl chain length leads to decreased tensile modulus but increased tensile yield strength and strain, indicating increased interfacial interactions with increased alkyl chain length. The 3C1-composite shows the highest fracture toughness with an improvement by 9% compared to neat iPP, whereas the other composites show decreased values of fracture toughness.