Vinyltriethoxysilane Research Articles

Preparation, properties of In‐situ silica modified styrene‐butadiene rubber and its silica‐filled composites

In this work, native emulsion polymerization styrene butadiene rubber (SBR) were first grafted by vinyltriethoxysilane (VTES) to SBR‐g‐VTES (VTES grafted SBR), second, the SBR‐g‐VTES were modified by different amount of TEOS (tetraethoxysilane) using in situ sol‐gel method, at the last, the extra silica was added into the in situ modified SBR system to get the modified SBR/silica composites using latex coagulation technology. The effect of different amount of TEOS on modified SBR/silica composites was also systematically studied, including the content of silica and utilization of silica, cure characteristics, physical mechanical properties and dynamic mechanical properties. The surface properties of modified SBR/silica composites were characterized by scanning electron microscope (SEM). It can be got that the grafting of VTES and in situ hydrolysis and condensation of TEOS can effectively inhibit the agglomeration and improve the mechanical properties of modified SBR/silica. It also can be found that modified SBR brings well physical and dynamic mechanical properties, wear resistance, and low rolling resistance to SBR, especially, when the TEOS is 3.0 g, the best overall performance of modified SBR/silica can be achieved. POLYM. COMPOS., 39:22–28, 2018. © 2016 Society of Plastics Engineers

Immobilization of Bromocresol Purple in Inorganic-Organic Sol-Gel Thin Film with Presence of Anionic and Non-ionic Surfactants

Sol-gel materials known as organically modified silicates (ORMOSILs) offer interesting features such as chemical and mechanical stability. In this paper VTES (vinyltriethoxysilane) and TEOS (tetraalkoxysilane) are mixed in 3:1 ratio. Sol-gel solution was prepared by hydrolysis process of precursors by using ethanol as solvent. After a while a pH-sensitive indicator bromocresol purple (BCP) and surfactant were incorporate into the sol-gel mixture. The percentage of sodium dodecyl sulfate (SDS) and polyethylene glycol (PEG) which act as surfactant were varied to observe the effect of improving host material's nanostructure as well as the interaction between BCP and sol-gel matrices. The absorption peak of the BCP dye changed significantly in the presence of surfactant compared to pure VTES: TEOS mixture (control) in the range of 400 to 450nm. The presence of BCP dye in the sol-gel mixture can be determined via FTIR spectrum with a =C–H stretch in aromatics observed at 3100-3000 cm-1 which represented the aromatic of the BCP structure. The addition of BCP and surfactant had influenced the FTIR spectra of VTES: TEOS sol-gel materials. Addition of an anionic surfactant to the sol-gel mixtures was found to increase the BCP dye and the sol-gel matrices interaction, thus reducing the dye's tendency to leach. This work shows that sol-gel derived matrices yield dyes with sufficient rigid environment and addition of the surfactant helps to improve the interaction of filler matrices. The anionic SDS shows better leaching resistant compared to non-ionic PEG surfactant. Results of this study offer an attractive possibility to optimize the doped sol gel matrices to be used as sensing material in aqueous condition.

Investigating into the liquid oxygen compatibility of a modified epoxy resin containing silicon/phosphorus and its mechanical behavior at cryogenic temperature

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (DOPO–TVS) was synthesized through a reaction between DOPO and triethoxyvinylsilane (TVS).

Synthesis and characterization of organic–inorganic hybrid microspheres

This study presents the synthesis of hybrid microspheres based on monomers of various chemical nature. As organic compounds, styrene and 1,4-divinylbenzene were used, whereas triethoxyvinylsilane (TEVS) was applied as an inorganic one. Four different systems with the increasing quantity of TEVS were studied. Then inorganic parts of TEVS were removed with aqueous solution of NaOH. Structure of the new materials was confirmed by FTIR-ATR, EDX–SEM and TGA analyses. Thermal resistance of the copolymers was assessed using the TG–DTG system. The synthesized hybrid materials exhibited highly developed porous structure that was confirmed from the low-temperature nitrogen adsorption data. The prepared materials were tested as sorbents for removing organic compounds from aqueous solutions using the SPE technique.

Synthesis and characterization of core/shell titanium dioxide nanoparticle/polyacrylate nanocomposite colloidal microspheres

Core/shell titanium dioxide (TiO2) nanoparticle/poly(methyl methacrylate-butyl acrylate-methacrylic acid) [P(MMA-BA-MAA)] nanocomposite colloidal microspheres have been successfully synthesized via in situ emulsion polymerization. TiO2 nanoparticles were firstly modified by silane coupling agent, vinyl triethoxysilane (A-151), to increase the dispersibility of TiO2 nanoparticles into the polyacrylate matrix. The A-151-modified TiO2 nanoparticles were characterized by Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques. The synthesized nanocomposite colloidal microspheres were characterized by TEM, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and differential scanning calorimetry analysis (DSC). The results showed that A-151 coupling molecules was chemically bonded on the TiO2 nanoparticles surface, and the amount of coated A-151 was 3.0 wt%. According to TEM micrographs and DLS results, the dispersibility of modified TiO2 nanoparticles was obviously improved. TEM analysis revealed that an obvious core/shell structure morphology was observed with the core TiO2 particles surrounded by a uniform 10∼15-nm thick polymer shell. SEM–EDS result showed that TiO2 nanoparticles were homogenously monodispersed in the polymer matrix. DSC measurements indicated a glass transition temperature (T g) enhancement of P(MMA-BA-MAA).

Synthesis and characterization of triethoxyvinylsilane surface modified layered double hydroxides and application in improving UV aging resistance of bitumen

Layered double hydroxides (LDH) surface modified by triethoxyvinylsilane (TEVS) was prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Ultraviolet and visible (UV–Vis) spectrophotometry. FTIR and XRD showed that TEVS has been successfully grafted onto the surface of LDH. Compared with LDH, the agglomeration between the TEVS surface modified LDH (TEVS-LDH) particles was obviously weakened according to SEM. UV–Vis reflectance and absorbance analyses indicated that TEVS-LDH possessed better UV reflectance and absorbance than that of LDH. Then the effects of TEVS-LDH and LDH on the physical and anti-aging properties of bitumen were thoroughly evaluated. The storage stability test showed that TEVS-LDH existed more stably than LDH in bitumen, which was due to the surface modification of LDH which improved the compatibility between LDH and bitumen. The results of physical properties tests showed that TEVS-LDH improved high-temperature behavior and had a less pronounced effect on the low temperature ductility of bitumen in contrast with LDH. Aging indices (viscosity aging index, softening point increment and ductility retention rate) and FTIR showed that TEVS-LDH exhibited better improvement than LDH on anti-ultraviolet aging of bitumen.

Preparation and characterization of polyhedral oligomeric silsesquioxane (POSS) using domestic microwave oven

This paper reports the preparation and characterization of polyhedral oligomeric silsesquioxane (POSS) using a domestic microwave oven. The hybrid nanomaterials were synthesized using the hydrolytic condensation of vinyltriethoxysilane (VTES) and a VTES/tetraethyl orthosilicate (TEOS) mixture. The samples were characterized by FTIR, 1H-NMR, 29Si-NMR, GPC, SEM, TEM, WAXD and TGA. The dielectric heating of the VTES and VTES/TEOS systems enabled the production of POSS with increased yield, showing rates 47 and 59 times faster than conventional heating, respectively. The POSS VTES samples prepared by dielectric and conventional heating showed very similar chemical characteristics. However, for the POSS obtained with the addition of TEOS the same behavior was not observed, because of the selective effect occasioned by microwave-assisted synthesis. The morphological shape of the hybrid clusters is dependent on the synthesis method and the precursor type. The simple approach used in this work represents an alternative to obtaining nanomaterials more efficiently.

Synthesis, thermal and mechanical behavior of a silicon/phosphorus containing epoxy resin

ABSTRACTA liquid silicon/phosphorus containing flame retardant (DOPO–TVS) was synthesized with 9,10‐dihydro‐9‐oxa‐10‐phosphapheanthrene‐10‐oxid (DOPO) and triethoxyvinylsilane (TVS). Meanwhile, a modified epoxy resin (IPTS–EP) was prepared by grafting isocyanate propyl triethoxysilane (IPTS) to the side chain of bisphenol A epoxy resin (EP) through radical polymerization. Finally, the flame retardant (DOPO–TVS) was incorporated into the modified epoxy resin (IPTS–EP) through sol–gel reaction between the ethyoxyl of the two intermediates to obtain the silicon/phosphorus containing epoxy resin. The molecular structures of DOPO–TVS, IPTS–EP and the final modified epoxy resin were confirmed by FTIR spectra and 1H‐NMR, 31P‐NMR. Thermogravimetric analysis (TGA), differential scanning calorimetry, and limiting oxygen index were conducted to explore the thermal properties and flame retardancy of the synthesized epoxy resin. The thermal behavior and flame retardancy were improved. After heating to 600°C in a tube furnace, the char residue of the modified resin containing 10 wt % DOPO–TVS displayed more stable feature compared to that of pure EP, which was observed both by visual inspection and scanning electron microscope (SEM). Moreover, the mechanical performance testing results exhibited the modified epoxy resins possessed elevated tensile properties and fracture toughness which is supported by SEM observation of the tensile fracture section. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42788.

Characterization of Fly Ash Modified with Vinyltriethoxysilane.

Here we report on the modification of fly ash (FA) with vinyltriethoxysilane (VTES) in order to enhance the dispersibility and avoid the agglomeration. FA was treated with nitric acid before the modification with VTES. The structure of fly ash particles before and after the modification was characterized by several sophisticated techniques including Fourier transform infra-red spectrum (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and size distribution analysis. The obtained results show that the VTES was grafted successfully onto the surface of FA, which significantly changes the surface properties of FA. It was also found that the thermal stability of modified FA (MFA) is much higher than that of the FA treated only with nitric acid. The size of the FA particles can also be controlled from 0.2 to 1.5 µm with increasing the loading of VTES on the surface of FA from 1 to 2 wt.%, revealing highly mono-distribution and low agglomeration. However, the agglomeration of the particles is observed when the content of VTES on the surface of FA exceeds 2 wt.%.

Mechanical and Thermal Properties of Hemp Fiber Reinforced High Density Polyethylene Composites

Hemp fiber reinforced composites was prepared using high density polyethylene (HDPE). Hemp fiber is a cellulosic fiber. It is used as reinforcement in thermoplastic matrix composite requires knowledge of their morphology and structure. In this paper, mechanical properties of chemically treated fiber reinforced HDPE composites were investigated over range of fiber content (0-50 wt%). The hemp fiber was alkali treated with 1-10 wt% to remove waxes and non-cellulosic surface components and triethoxyvinyl silane treated with 0.5-3 wt% to improve a better fiber-matrix interface. Fiber/matrix adhesion was assured by the use of use of polyethylene-graft-maleic anhydride (PE-g-MA) as a compatibilizer. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-Ray Diffraction (XRD) and tensile tests were carried out for hemp fibers high density polyethylene composite. Findings indicate that a 5 wt% NaOH treatment effectively improved the fiber-matrix interface resulting in improved mechanical properties. All 40 wt% alkali treated fiber reinforced HDPE composites displayed higher young’s modulus and lower elongation at break as compared to neat HDPE, compatibilization with PE-g-MA resulted in an increased young modulus of the composites as consequence of an improved fiber-matrix interfacial adhesion.

Influence of vinyltriethoxysilane concentration on structural and luminescent characteristics of cerium doped yttrium based silicate phosphors

Cerium doped yttrium silicates phosphors (YSO:Ce) were prepared by gel combustion using vinyltriethoxysilane (VTEOS) as silicon sources along with aspartic acid as fuel and yttrium-cerium nitrate as oxidizer. The study presents the influence of VTEOS amount in the synthesis mixture on the structural and luminescent characteristics of silicate phosphors. The understanding of precursor׳s decomposition was achieved on the basis of thermal analysis in association with gas evolved analysis. XRD, FTIR and XPS were used to reveal the structural changes that occur with VTEOS molar amount variation from 1 to 3mol. It was found that the main crystalline phase was X2-Y2SiO5. The luminescent characteristics of phosphors were measured at room and low temperature (10–300K) based on emission and excitation spectra. Under UV excitation, YSO:Ce exhibits blue emission due to electron transition in Ce3+ from 5d level to the ground state levels (2F5/2, 2F7/2). The emission intensity increases from 70% to 120% along with VTEOS amount, explained by the improvements in structural homogeneity. Incorporation of cerium in different sites (Ce1 and Ce2) is discussed based on PL and PLE spectra measured at low temperature (10K).

Sodium montmorillonite modified with methacryloxy and vinylsilanes: Influence of silylation on the morphology of clay/unsaturated polyester nanocomposites

Unsaturated polyester resins are widely used in the automotive, construction and naval industries. To further widen their application, they may be combined with clay minerals, which are advantageous due to their thermal, barrier, inflammability and stiffness characteristics. In order to avoid agglomeration and improve the interaction of Cloisite® Na+ montmorillonite (Mt) with an unsaturated polyester matrix, this study focused on clay minerals modified with compatible silanes, vinyltriethoxysilane (VTES) and γ-methacryloxypropyltrimethoxysilane (MPS), and their use in composites in comparison with nanocomposites prepared using commercial clays (Cloisite® 30B and Cloisite® 15A). Functionalization of Cloisite®Na with MPS and VTES was confirmed by the appearance of characteristic infrared bands and the increase in the basal spacing. The nanocomposites containing silane-modified clays prepared in hydro-alcoholic solution showed the best result compared with ethanol solution. The presence of iron changed the color of the CNa and C30B samples and all of those prepared with silane modified Na-Mt-clays.

The structure effect upon gallic acid re-binding in molecularly imprinted organosilica

This paper debates the effect of the stabilizer (vinyl benzyl trimethyl ammonium chloride—VBTAC or cetyl trimethyl ammonium chloride—CTAC) and the structure (typical SiO2 matrix or inorganic–organic interpenetrated matrix) influence in molecular imprinting of gallic acid-polyphenol class of templates. For this purpose, gallic acid-imprinted particles were obtained via typical polycondensation sol–gel reactions and via sol–gel/radical polymerization concurrent reactions of tetraethoxy silane (TEOS) and aminopropyl ethoxy silane (APTES) or vinyl triethoxy silane (VTES), respectively. The influence of the mesophase formation and stabilizer nature upon the re-binding of gallic acid was investigated using thermal, infrared and morphology measurements. Adsorption assays of organosilica particles were well correlated with their physical properties. Unlike the polycondensation of TEOS with APTES in the presence of CTAC, concurrent radical polymerization of VBTAC consumed the vinyl functionalities of VTES, decreasing the capacity of VBTAC to mediate the mesophase formation and the capacity of VTES to coordinate template molecules; hence, both the binding capacity and the “memory” effect of the interpenetrated organosilica structure were significantly affected.

Thermal and mechanical properties of liquid silicone rubber composites filled with functionalized graphene oxide

ABSTRACTTo improve the thermal and mechanical properties of liquid silicone rubber (LSR) for application, the graphene oxide (GO) was proposed to reinforce the LSR. The GO was functionalized with triethoxyvinylsilane (TEVS) by dehydration reaction to improve the dispersion and compatibility in the matrix. The structure of the functionalized graphene oxide (TEVS‐GO) was evaluated by Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD), and energy dispersive X‐ray spectroscopy (EDX). It was found that the TEVS was successfully grafted on the surface of GO. The TEVS‐GO/LSR composites were prepared via in situ polymerization. The structure of the composites was verified by FTIR, XRD, and scanning electron microscopy (SEM). The thermal properties of the composites were characterized by TGA and thermal conductivity. The results showed that the 10% weight loss temperature (T10) increased 16.0°C with only 0.3 wt % addition of TEVS‐GO and the thermal conductivity possessed a two‐fold increase, compared to the pure LSR. Furthermore, the mechanical properties were studied and results revealed that the TEVS‐GO/LSR composites with 0.3 wt % TEVS‐GO displayed a 2.3‐fold increase in tensile strength, a 2.79‐fold enhancement in tear strength, and a 1.97‐fold reinforcement in shear strength compared with the neat LSR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42582.

Lignin as coupling agent in EPDM rubber: thermal and mechanical properties

EPDM rubbers were prepared and the effect of lignin as coupling agent was investigated by means of mechanical and thermal properties. As a contrast, using vinyl triethoxy silane (VTS) coupling agent in EPDM rubber was also studied. The median diameter and the specific surface area of lignin used were 6.61 μm and 722.24 m2 kg−1, respectively. Properties of EPDM rubbers were assessed by tensile testing, thermogravimetric analysis (TG/DTG) and scanning electron microscopy (SEM). The results showed that using lignin coupling agent, the mechanical properties were better than that of pure and adding VTS’ EPDM rubbers. Thermal analysis revealed that containing lignin rubber had better thermal stability. SEM results indicated that the inter-phase cohesion between the lignin molecule and EPDM particles was enhanced.

Preparation and properties of natural rubber with filler nanomatrix structure

Natural rubber with filler nanomatrix structure was prepared by forming chemical linkages between natural rubber particles and filler nanoparticles. The filler nanomatrix structure was formed by graft copolymerization of vinyltriethoxysilane (VTES) onto natural rubber particles in the latex stage followed by casting of the latex to prepare an as-cast film. The silica nanoparticles were produced during the graft copolymerization through hydrolysis and condensation, i.e., sol–gel reaction; hence, they linked to the natural rubber particles. The nanomatrix structure was observed by transmission electron microscopy, in which the natural rubber particles of about 1 μm in diameter were well dispersed in the filler nanomatrix. Tensile properties were significantly improved by forming filler nanomatrix structure. The loss modulus and loss tangent of the natural rubber with the filler nanomatrix structure were almost independent of deformation frequency in the rubbery plateau region, which was explained to be due to the energetic elasticity and entropic elasticity characteristic of the nanomatrix structure.

Effects of fermentation by-products and inhibitors on pervaporative recovery of biofuels from fermentation broths with novel silane modified silicalite-1/PDMS/PAN thin film composite membrane

The influence of different bioethanol fermentation broths components (fermentation by-products, and the common inhibitory compounds present in lignocellulosic hydrolysates) on the pervaporation performance of the vinyltriethoxysilane (VTES) modified silicalite-1/PDMS/PAN thin-film composite membrane was detailedly investigated in this work. The results showed that succinic acid and glycerol are impermeable components, whereas formic acid, acetic acid, and furfural can permeate through the membrane. Succinic acid have no obvious influence on the membrane performance. Meanwhile, the composite membrane can effectively remove formic acid, acetic acid, and furfural present in lignocellulosic hydrolysates. The maximum furfural/water selectivity of 95 and furfural flux of 130g/m2h were obtained with adding 15g/L furfural into 2wt.% ethanol binary solution at the feed temperature of 35°C. This research reveals a novel detoxification method of lignocellulosic hydrolysates and a potential approach for furfural production as well.

Aluminum pigments encapsulated with hybrid silica film with carboxyl groups and their stability and dispersibility in aqueous media

Aluminum pigments encapsulated with hybrid SiO2 film with carboxyl (–COOH) groups were prepared through a sol‐gel process of tetraethoxysilane (TEOS) and vinyl triethoxysilane (VTES), followed by radical copolymerization of methyl methacrylate (MMA) and acrylic acid (AA) with the vinyl group of VTES. The composite aluminum pigments were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). Their stability in acid media as well as dispersibility in water were also evaluated. It was found that VTES and TEOS could simultaneously hydrolyze and condense with hydroxyl groups on the surface of aluminum particles to form inorganic‐organic hybrid films, and copolymerization of MMA and AA could provide the film surface with –COOH groups. This helps the composite aluminum pigments disperse better in water than raw aluminum pigments (raw Al) counterparts. Compared with the serious corrosion problem of raw Al, which generated about 113 mL H2 in acid media of pH=1 in 30 days, the composite aluminum pigments showed much better anticorrosion performance (with only about 0.5 mL H2). The waterborne coatings made with this composite aluminum pigments showed great improvements on adhesive performance and stability in 0.1 mol/L H2SO4 or NaOH media.

Synthesis of molecularly imprinted polypyrrole as an adsorbent for solid-phase extraction of warfarin from human plasma and urine.

The aim of this work was to develop a method for the clean-up and preconcentration of warfarin from biological sample employing a new molecularly imprinted polymer (MIP) as a selective adsorbent for solid-phase extraction (SPE). This MIP was synthesized using warfarin as a template, pyrrole as a functional monomer and vinyl triethoxysilane as a cross-linker. The molar ratio of 1:4:20 (template-functional monomer-cross-linker) showed the best results. Nonimprinted polymers (NIPs) were prepared and treated with the same method, but in the absence of warfarin. The prepared polymer was characterized by Fourier transmission infrared spectrometry and scanning electron microscopy. An adsorption process (SPE) for the removal of warfarin using the fabricated MIPs and NIPs was evaluated under various conditions. Effective parameters on warfarin extraction, for example, type and volume of elution solvent, pH of sample solution, breakthrough volume and maximum loading capacity, were studied. The limits of detection were in the range of 0.0035-0.0050 µg mL(-1). Linearity of the method was determined in the range of 0.0165-10.0000 µg mL(-1) for plasma and 0.0115-10.0000 µg mL(-1) for urine with coefficients of determination (R(2)) ranging from 0.9975 to 0.9985. The recoveries for plasma and urine samples were >95%.

Investigation on the film surface and bulk properties of fluorine and silicon contained polyacrylate

Abstract A series of fluorine and silicon acrylic latexes have been prepared from acrylic monomers, 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) and vinyltriethoxysilane (VTES) via emulsion polymerization. Morphology and particle size distribution were evaluated by transmission electron microscopy (TEM) and dynamic light scattering (DLS) methods. Surface properties of latex films were investigated in terms of ATR-FTIR spectrometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and water resistance measurement. It is indicated that fluorine content at the surface of fluorosilicone acrylic film decreased as the film forming temperature was increased. A high temperature favored silicon condensation at the film surface, which limited migration ability of fluorine chains. Fluorine segment contributed to surface hydrophobicity while silicon component was beneficial to improve water repellency of the film bulk. Silicon containing particles were more difficult to coalesce than fluorine acrylic particles due to the rigid crosslinked network derived from silanol crosslinking.