Silane Functional Groups Research Articles

Improved thermal, dielectric, and mechanical properties of acrylate composites with diethylene glycol and silane-treated ternary hybrid fillers via three-dimensional vat photopolymerization

Rapid advances in electronic devices have led to the production of highly integrated structures, which are prone to the thermal accumulation problem. Accordingly, polymer-based composites have been introduced to solve the thermal dissipation problem and endow energy storage properties. In this study, an acrylate polymer-based composite with boron nitride (BN), barium titanate (BT), and carbon nanotubes (CNTs) ternary fillers was fabricated via three-dimensional (3D) vat photopolymerization (VPP). To improve the processability of the printing, diethylene glycol (DEG) was added as a viscosity reducer, and ternary fillers were surface-treated with silane functional groups. The surface-treated ternary composite improved tensile strength, thermal conductivity, and dielectric constant compared to a composite composed of raw ternary fillers. Furthermore, the composites with silane-treated BN and CNTs showed thermal conductivity of 2.796 W/(m∙K) and thermal conductivity enhancement of 1153% compared to the acrylate matrix. The dielectric constants and electrical insulation of the composites were also investigated. The proposed method ushers a new era in polymer-based composites with improved thermal conductivity and energy storage properties as well as desired and controlled complex structures through swift and sophisticated 3D VPP printing.

Investigation of mechanisms of an upflow-downflow siliceous sand filtration system for surfactants bathroom grey water treatment.

Sustainable decentralized wastewater treatment systems (DEWATS) at the local level are considered as a smart alternative for small communities particularly in arid areas. The present study examines the mechanisms of an upflow-downflow Siliceous Sand (SS) filtration system involved in surfactants bathroom grey water treatment. In order to get a better understanding of the mechanisms involved in surfactants removal, particle size distribution and Fourier transform infrared (FTIR) spectroscopy of the SS particles were performed. Optimization of the upflow-downflow SS filtration system, operated following operational conditions of hydraulic load rate (HLR) and SS amounts, results indicates an average removal efficiency (ARE) of 93.7% reached with respect to surfactants removal. Results showed also that the resulting silicate materials react with surfactants in a cooperative assembly process involving the interaction of SS particles with surfactants aggregates. Brunauer, Emmett and Teller (BET) surface area, pore volume (Vp), and pore size were found to be significantly reduced post-filtration with respectively 3.39%, 24.31%, and 21.86% reduction. From FTIR spectroscopy analysis of the Sulfonates, Silanol and Silane functional groups appear to be involved in mesoporous constructed micelle organization for surfactants removal. Such geo-materials could be green and sustainable for various applications in water and environmental engineering.

Experimental and Theoretical Studies toward Superior Anti-corrosive Nanocomposite Coatings of Aminosilane Wrapped Layer-by-Layer Graphene Oxide@MXene/Waterborne Epoxy.

Herein, layer-by-layer MXene/graphene oxide nanosheets wrapped with 3-aminopropyltriethoxy silane (abbreviated as F-GO@MXene) are proposed as an anti-corrosion promoter for waterborne epoxies. The GO@MXene nanohybrid is synthesized by a solvothermal reaction to produce a multi-layered 2D structure without defects. Then, the GO@MXene is modified by silane wrapping under a reflux reaction, in order to achieve chemical stability and to create active sites on the nanohybrid surface for reaction with the polymer matrix of the coating. The organic coating modified with 0.1 wt % F-GO@MXene has revealed superior corrosion protection efficiency than the organic coatings modified with either F-GO or F-MXene nanosheets. The impedance modulus at low frequency for the pure epoxy, epoxy/F-MXene, epoxy/F-GO, and epoxy/F-GO@MXene coatings is 4.17 × 105, 5.5 × 108, 4.46 × 108, and 1.14 × 1010 Ω·cm2 after 30 days of immersion in the corrosive media, respectively. The remarkable anti-corrosion property is assigned to the intense effect of the nanohybrid on the barrier performance, surface roughness, and adhesion strength of the epoxy coating. The complemental analysis based on first-principles density functional theory reveals that the adhesion strength related to the silane functional groups in its complexes follows the order F-GO@MXene > F-MXene > F-GO. The enhanced stabilization predicted on the GO@MXene nanohybrid ultimately stems from the combined role of the electrostatic and van der Waals forces, suggesting an increase in the penetration path of the corrosive media.

Influence of functionalized S–SBR on silica–filled rubber compound properties

Styrene–butadiene–Rubber, SBR, is most often used in tread compounds in order to improve the Rolling Resistance (RR). The functionalized SBRs are used to increase the polymer–filler interaction in the compound to improve RR. In this study, the effect of different types of functional groups in SBR was investigated. Several types of functionalized S–SBR’s were synthesized by anionic polymerization: (i) SBR with an amine group at one end of the polymer chain, (ii) SBR with an alkoxy silane group at one end (iii) SBR with an amine group at one end and an alkoxy silane group at the other end of the polymer chain. A model reaction of silanization was conducted in a solvent to estimate how the amine functional group affects the silanization. Silica filled compounds were prepared with these SBR types. Payne effect and bound rubber measurement were done. The model silanization reaction of TESPT (Bis(triethoxysilylpropyl)tetrasulfide) with silica in the presence of amine shows that a higher amount of ethanol (EtOH) is released from TESPT compared to the amine free system. This result indicates that the silanization reaction can be accelerated by the presence of an amine functional group at the SBR polymer chain used in silica–filled compounds. The amine functionalized SBR and the alkoxy silane functionalized SBR show less Payne effect of the compounds which indicates that both functional groups can decrease the filler–filler interaction. More chemical bound rubber was obtained in branched SBRs compared to the corresponding linear SBRs. A branched polymer chain has a higher molecular weight compared to the linear type. Therefore, when one branched polymer chain reacts with silica or creates a silica–silane–polymer bond, more bound rubber can be obtained for the branched than for the linear type. The compound of the SBR with the alkoxy–silane functional group shows lower tan δ compared to the non–functionalized SBR and the amine functionalized SBR compounds. The influence of the type of functionalization of the SBR on tan δ at 70 °C was more significant in branched SBRs than in linear SBRs, due to the before–mentioned effect of the functional group on silanization and bound rubber.

Fully Printed Flexible Piezoelectric Nanogenerators with Triethoxyvinylsilane (TEVS) Coated Barium Titanate (BTO) Nanoparticles for Energy Harvesting and Self‐Powered Sensing

AbstractThe improvement of wearable electronics is making energy harvesters appealing, as they lessen the requirement for regular recharge of wearable gadgets. In this work, fully printed, flexible piezoelectric nanogenerators (PENGs) with excellent performance are created using a 3D printing technology. This fully‐printing method is based on triethoxyvinylsilane (TEVS) coated barium titanate (BTO) nanoparticles, polyvinylidene fluoride‐co‐trifluoroethylene (PVDF–TrFE), and silver electrode for additive manufacturing. The organic vinyl silane (VS) functional groups, which form a strong bond between inorganic nanoparticles and polymer, contribute to the homogeneous dispersion of BTO nanoparticles in the matrix. Consquently, these fully printed VS–BTO/PVDF–TrFE PENGs outperform their untreated counterpart in terms of output voltage and power density, with a higher output voltage of 54 V even after 13 500 cycles and a higher power density of 28.5 µW cm−2. In practice, as‐printed devices may actively adapt to human movement and detect the pulse from multipoint mechanical activity identification. The fully printed PENGs developed in this work show excellent potential to be used in wearable electronics for a new generation of sensing applications.

Scratch Properties of Clear Coat for Automotive Coating Comprising Molecular Necklace Crosslinkers with Silane Functional Groups for Various Environmental Factors

Automotive coatings, which comprise multiple layers, i.e., primer, base coating, and clear coat layers, are exposed to various environmental conditions that pose various types of damages to them. In particular, the outer layer of the automotive coating, i.e., the clear coat, is affected significantly by such damages. Therefore, a reliable and durable clear coat must be developed to improve the appearance of automobiles. In this study, a new clear coat based on an acrylic-based clear coat modified using polyrotaxane crosslinkers, which are necklace-shaped supramolecules composed of ring-shaped host molecules, is developed and characterized. The effects of polyrotaxane and silane on the scratch properties and mechanisms of the clear coating are analyzed. It is observed that the critical loads of the clear coat from scratch tests can be improved by adding optimal molecular necklace crosslinkers comprising silane functional groups. The improvement in the scratch properties of the modified acrylic-based clear coat may be attributed to the crosslinking characteristics and dynamic molecular movements of the polyrotaxane. In addition, the effects of environmental factors on the scratch characteristics of the modified acrylic-based clear coat are investigated by addressing the scratch durability of the clear coat.

Improvement of the thermal conductivity and tribological properties of polyethylene by incorporating functionalized boron nitride nanosheets

The heat generated by friction and wear between contact surfaces is detrimental to the performance of polymeric materials due to the low thermal conductivity of polymer materials. This work presents the effect of boron nitride (BN) nanosheets on the thermal and tribological properties of polyethylene (PE) materials. The molecular interaction between BN nanosheets and PE matrix was enhanced by functionalizing BN nanosheets with silane functional groups. It was observed that adding just 5 wt% silane modified BN (sBN) nanosheets can increase the thermal conductivity of PE materials by 33% and minimizes the generation of hot spots due to fast heat dissipation. In addition, the wear rate is reduced by 35% in PE-sBN composites in comparison to PE materials.

Preferential Protection of Low Coordinated Sites in Pt Nanoparticles for Enhancing Durability of Pt/C Catalyst

Protecting low coordinated sites (LCS) of Pt nanoparticles, which are vulnerable to dissolution, may be an ideal solution for enhancing the durability of polymer electrolyte fuel cells (PEMFCs). However, the selective protection of LCSs without deactivating the other sites presents a key challenge. Herein, we report the preferential protection of LCSs with a thiol derivative having a silane functional group, (3-mercaptopropyl) triethoxysilane (MPTES). MPTES preferentially adsorbs on the LCSs and is converted to a silica framework, providing robust masking of the LCSs. With the preferential protection, the initial oxygen reduction reaction (ORR) activity is marginally reduced by 8% in spite of the initial electrochemical surface area (ECSA) loss of 30%. The protected Pt/C catalyst shows an ECSA loss of 5.6% and an ORR half-wave potential loss of 5 mV after 30,000 voltage cycles between 0.6 and 1.0 V, corresponding to a 6.7- and 2.6-fold durability improvement compared to unprotected Pt/C, respectively. The preferential protection of the vulnerable LCSs provides a practical solution for PEMFC stability due to its simplicity and high efficacy.

Polyethylene-BN nanosheets nanocomposites with enhanced thermal and mechanical properties

Polyethylene (PE) are in demand for electrical insulation and thermal management applications; however, their low mechanical and thermal properties pose major challenges. Herein, we report on novel properties of PE-boron nitride (BN) nanocomposites prepared by melt compounding followed by injection molding. The thermal and mechanical properties of silane-functionalized (sBN) and non-functionalized (pBN) PE-BN nanocomposites were studied in order to assess the role of silane functional groups at the interface of BN nanosheets and PE matrix. In comparison with PE materials, addition of 5 wt % BN nanosheets increases tensile modulus of elasticity by 37 and 42%, flexural modulus of elasticity by 24 and 30%, tensile strength by 15 and 27%, and storage modulus by 80 and 91% for pBN and sBN nanocomposites, respectively. Besides mechanical reinforcement, thermal and thermomechanical properties were evaluated for PE-BN nanocomposites. While thermal stability of PE-pBN and PE-sBN nanocomposites was comparable, coefficient of thermal expansion was decreased by 12 and 20% at 5 wt % pBN and sBN nanosheets, respectively. These polymer nanocomposites with enhanced mechanical and thermal properties can be an excellent choice for application in insulation materials, including thermal interface layers in electronic devices.

Inorganic–organic hybrids based on sepiolite as efficient adsorbents of caffeine and glyphosate pollutants

Sepiolite clay mineral was functionalized with (3-chloropropyl)triethoxysilane (ClPTES) or 3-[tri(ethoxy/methoxy)silyl] propylurea (TEMSPU) alkoxides and tested as adsorbent for herbicide glyphosate and also of caffeine, two pollutants with very different chemical composition. The materials obtained were characterized by X-ray diffractometry, infrared spectroscopy, thermal analysis, scanning electron microscopy and nitrogen adsorption at −196 °C, and submitted to toxicity and desorption tests. Silane functional groups blocked sepiolite active positions, and adsorption occurred within the zeolitic channels and on the surface of the functionalized solids. Caffeine and glyphosate effectively interacted with urea groups from grafted alkoxide, which could lower the mobility of the adsorbed contaminants. Glyphosate adsorbed on functionalized sepiolite derivatives showed low toxicity.

Silane–based modified papers and their extractive phase roles in a microfluidic platform

Herein, some (modified) paper–based substrates were prepared and utilized as extractive phases in a microfluidic device and their extraction performances examined for analytes with different polarities. Reagents including hexadecyltrimethoxysilane (HDTMS), phenyltrimethoxysilane (PTES), (3-aminopropyl) triethoxysilane (APTES) and 3–(2,3–epoxypropoxy) propyltrimethoxysilane (EPPTMOS) were implemented for the modification process. Due to the induction of different silane functional groups, it was anticipated to have various interactions for the tested analytes. Eventually, the prepared paper sheets were used as extractive phases for solid–phase extraction within a microfluidic system. The microfluidic setup not only improves the mechanical stability of the paper–based phases but also facilitated the mass transfer process and decreases the energy consumption. The selected analytes contained antidepressant drugs, organophosphates and triazine toxins, having different structures and polarities. Afterward, the existing interactions between the paper–based sorbents and the selected analytes were investigated by Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA) for data analysis. According to the obtained data, the PTES modified surface paper was selected for quantitative investigation and optimization. The major parameters associated with the extraction performance were studied. A linear range was obtained for amitriptyline and trimipramine, 0.05–200 μg L−1, and the calibration graph for clomipramine was linear in the range of 0.02–200 μg L−1. The employment of microfluidic device in conjunction with gas chromatography-mass spectrometry led to the limits of detections of 0.005–0.01 μgL−1 for the antidepressant drugs. The relative recoveries for the tested drugs in urine samples were in the range of 95–103%.

A new way synthesis of expanded graphite as a thermal filler to enhance the thermal conductivity of DGEBA resin as thermal interface material

In this work, a facile two-step method for the synthesis of highly thermal conductive expanded graphite (EG) was proposed. A binary component system of ammonium persulfate and concentrated sulfuric acid was prepared for the synthesis of EG from natural graphite flakes in which the former one acted as an oxidizing agent and the latter one used as an intercalating agent. Further, the silane functionalization of EG (mEG) was purposefully completed, as confirmed from the X-ray diffraction and Fourier transform infrared spectroscopy analysis. Epoxy-based thermal interface materials (TIMs) were fabricated with reinforcing EG and mEG by stir-casting method at different filler fraction. The guarded heat flow meter method indicated that the enhancement in thermal conductivity (TC) was 12.12-fold at 10 wt% loading of mEG (mEG10-Ep) than neat epoxy. The binding strength of mEG10-Ep composite tuned to 6.18 ± 0.8 MPa and determined by a single lap shear test, which confirms better reinforcing effect of silane functionalized EG than neat EG counterpart. The same was also corroborated from porosity evaluation of the composite system. At 50% weight loss in nitrogen atmosphere, thermogravimetric analysis revealed that the composite was stable up to 430°C. Dynamic mechanical analysis was engaged to estimate the glass transition temperature ( T g) of the epoxy composite system, which validates its prospective application as preferred TIMs in the electroactive device. The electrical conductivity of composite was deteriorated due to the encapsulation of EG with nonconductive silane functional groups. The uniform dispersion was achieved by mEG-filled composite as compared to its EG counterpart, which was visualized from fracture surface through scanning electron microscopy.

Bioactivity, Degradation, and Mechanical Properties of Poly(vinylpyrrolidone-co-triethoxyvinylsilane)/Tertiary Bioactive Glass Hybrids.

Currently, composite and class I hybrid biomaterials are used for tissue regeneration applications. To improve and better control biomaterial properties, we synthesized class II organic/inorganic (O/I) hybrids, in which organic polymers and inorganic tertiary bioactive glass (TBG) were covalently cross-linked. To tailor their microstructure, bioactivity, degradation, and mechanical properties, we altered the degree of cross-linking by varying the amount of functional groups in the polymer that mediate covalent bonding to the TBG. We synthesized class II hybrids in a two-step process: first, vinylpyrrolidone (VP) and triethoxyvinylsilane (TEVS) were copolymerized at various molar ratios to obtain different amounts of silane functional groups in the copolymer; second, TBG and the copolymer were mixed and allowed to undergo hydrolysis and polycondensation forming Si-O-Si- and Si-O-P-bridging networks between the organic and inorganic phases. Higher amounts of functional groups increased copolymer-TBG covalent bonding and decreased degradation and the release of TBG dissolution products. Incubation in simulated body fluid led to biomimetic apatite deposition on the hybrid biomaterial surfaces, which was primarily dependent on O/I weight ratios. A higher TBG content improved apatite deposition and biocompatibility. Porous and interconnected three-dimensional scaffolds, fabricated by indirect 3D printing using polycaprolactone as a sacrificial template, had intriguing yield and compressive strengths, compressive moduli, and toughness. These studies demonstrate, for the first time, that the functionality of our synthesized copolymers greatly affects the nature of O/I matrix formation and degradation behavior of the class II hybrid biomaterials, creating possibilities for tailoring the physical, biochemical, and mechanical properties of scaffold biomaterials for tissue regeneration and related applications.

Silane coatings of metallic biomaterials for biomedical implants: A preliminary review.

In response to increased attention in literature, this work provides a qualitative review surrounding the application of silane-based coatings of metallic biomaterials for biomedical implants. Included herein is both a brief summary of existing knowledge and concepts regarding silane-based thin films, along with an analysis of recent peer-reviewed publications and advances towards their practical application for biomedical coatings. Specifically, the review identifies innovative silane-based coatings according to their molecular identity and film structure and analyses their impact on the biocorrosion resistance, protein adsorption, cell viability, and antimicrobial properties of the overall coated implant. It is shown that a range of common silanes clearly exhibit promising properties for biomedical implant coatings, but further work is needed, particularly on mechanisms of physiological interaction and characteristic effects of silane functional groups, before seeing clinical use. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2901-2918, 2018.

Earth-Abundant Transition Metal Catalysts for Alkene Hydrosilylation and Hydroboration: Opportunities and Assessments.

The addition of a silicon-hydrogen or a boron-hydrogen bond across a carbon-carbon multiple bonds is a well-established method for the introduction of versatile silane and borane functional groups to base hydrocarbon feedstocks. Transition metal catalysis, historically with precious second- and third- row transition metals, has been used to broaden the scope of the hydrofunctionalization reaction, improve reaction rate and enhance selectivity. The anti-Markovnikov selectivity of platinum-catalyzed hydrosilylation of alkenes, for example, is an enabling synthetic technology in the multibillion-dollar silicones industry. Increased emphasis on sustainable catalytic methods and more economic processes has shifted focus to catalysis with more earth-abundant transition metals such as iron, cobalt and nickel. This review describes contemporary approaches and offers a contextual analysis of catalytic alkene hydrosilylation and hydroboration reactions using first-row transition metals. Emphasis is placed on defining advances in the field, what constitutes catalyst cost, safety, and important design features to enable precious metal-like reactivity, as well as new chemistry that is unique to first-row transition metals.

To What Extent Can Hyperelastic Models Make Sense the Effect of Clay Surface Treatment on the Mechanical Properties of Elastomeric Nanocomposites?

The poor knowledge about nonlinear mechanical behavior of elastomer nanocomposites arises from the incomplete information on the interface. Application of hyperelastic models provides more insights into the nature and the situation of interaction between the elastomeric matrix and nanofillers. The current work seeks to address the effect of interphase strength on tensile properties of the elastomer nanocomposites under large deformations. Acrylonitrile butadiene rubber (NBR)/clay nanocomposite is selected for modeling on account of complexities associated with exfoliation/intercalation of clay platelets. In particular, it is aimed to specify to what extent hyperelastic models can capture the effect of clay surface functionalization on the mechanical behavior of nanocomposites. Attachment of silane functional groups to the clay surface is confirmed by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and thermogravimetric analyses. Different hyperelastic models are examined to detect the characteristic of NBR/clay nanocomposites. The powerfulness/weakness of the used models are featured by calculating the strain energy functions and material parameters, meanwhile, by comparing model outputs with experimental data of tensile tests. image

Role of Atomic Layer Functionalization in Building Scalable Bottom-Up Assembly of Ultra-Low Density Multifunctional Three-Dimensional Nanostructures

Building three-dimensional (3D) structures from their constituent zero-, one-, and two-dimensional nanoscale building blocks in a bottom-up assembly is considered the holey grail of nanotechnology. However, fabricating such 3D nanostructures at ambient conditions still remains a challenge. Here, we demonstrate an easily scalable facile method to fabricate 3D nanostructures made up of entirely zero-dimensional silicon dioxide (SiO2) nanoparticles. By combining functional groups and vacuum filtration, we fabricate lightweight and highly structural stable 3D SiO2 materials. Further synergistic effect of material is shown by addition of a 2D material, graphene oxide (GO) as reinforcement which results in 15-fold increase in stiffness. Molecular dynamics (MD) simulations are used to understand the interaction between silane functional groups (3-aminopropyl triethoxysilane) and SiO2 nanoparticles thus confirming the reinforcement capability of GO. In addition, the material is stable under high temperature and offers a cost-effective alternative to both fire-retardant and oil absorption materials.

Synthesis of high dispersible hydrophilic poly(ethylene glycol)/vinyl silane grafted silica nanoparticles to fabricate protein repellent polyethylene nanocomposite

Fabrication of protein repellent polymeric surface is a challenging issue for researchers in manufacturing biocompatible composites and low fouling membranes. In this study, poly(ethylene glycol) (PEG) and vinyl silane functional groups grafted silica nanoparticles (NPs) were synthesized by using one-pot/one-step sol-gel method. The fabricated NPs were dispersed in the high density polyethylene (HDPE) matrix to analyze the protein repellent property of HDPE sheets. FTIR results confirmed the successful grafting of both PEG and vinyl moieties on the silica NPs. TEM and DLS analyses showed that in the presence of both PEG and vinyl functional groups, the particles’ sizes were reduced to about 10nm. Dispersion of NPs in HDPE was obtained through blending in the presence of an initiator followed by the characterizations. The results obtained from backscatter electrons (BSE) images of HDPE nanocomposites revealed that PEG grafted silica NPs agglomerated in the HDPE matrix due to the lack of interaction between NPs and polymer molecular chains. However, dispersion of modified silica NPs was greatly improved in presence of vinyltrimethoxysilane (PEG/vinyl grafted silica NPs) due to the good compatibility between vinyl functional group of NPs and HDPE molecular chains. The contact angle of pure HDPE flat sheet sample was also reduced from 127 to 64 degree by adding 4% of PEG/vinyl grafted silica NPs due to the inherent hydrophilic characteristic of PEG. Static protein adsorption test showed that presence of vinyl moieties in the PEG modified NPs, significantly improved the percent reduction in protein adsorption, e.g. in case of 4wt% PEG/vinyl grafted silica NPs, it decreased from 0.0230 to 0.0012mg/(mlmm2) (>94%).

Thermal conductivity of polypropylene composites filled with silane-modified hexagonal BN

The aim of this study is to increase thermal conductivity of polypropylene (PP) composites filled with hexagonal boron nitride particles. Two types of BN with different types of surface treatment were used – pristine and covered with 3-amino-propyl-3-ethoxy-silane (APTES), which was bonded to hydroxyl groups, formed on the h-BN surface by annealing at 1100 °C. The presence of covalently bonded silane functional groups on the surface of h-BN particles was proved by Fourier transform infrared spectroscopy (FTIR) method. Surface treatment of h-BN particles allowed to introduce 3-times increased amount of the filler in the composite produced by extrusion casting technique as compared with non-treated h-BN filler. The thermal conductivity of PP composites filled with surface-modified h-BN was effectively enhanced – up to 2 times as compared with the composite filled with pristine h-BN and more than 2.5–4 times as compared with pure PP.

Study of the modification of montmorillonite with monofunctional and trifunctional vinyl chlorosilane

Montmorillonite (Cloisite®Na+) was modified with dimethylchlorovinylsilane (DMCVS) and trichlorovinylsilane (TCVS), in order to replace the silanol groups of clay mineral with silane vinyl groups (silylation reaction). The grafting reaction was studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Variation of the grafted amount and the grafting yield was evaluated as a function of the initial silane concentration. The grafted amount was increased with both mono- and trichlorosilane concentrations; where, the reaction yield decreased. Since the reaction will liberate HCl, the effect of the presence of NaHCO3 in the reaction media, was studied. Silylation with monofunctional silane leads to higher grafting amount compared to silylation with trifunctional one. The mechanism of silylation reaction was determined and the effect of the number of silane functional groups on the reaction mechanism was studied. The highest grafted amount and grafting yield were achieved with the initial silane concentration of ~4mmol/g of DMCVS. The basal spacing of the silylated montmorillonites (Mt) was observed to be more than the basal spacing of pristine Mt.