Vinyltriethoxysilane Research Articles

Preparation and Surface Modification of SiO<sub>2 </sub>Particles Used in Electronic Ink

In order to improve the surface properties of SiO2 particles, SiO2 particles were modified by vinyl triethoxysilane, SiO2 particles and vinyl triethoxysilane modified SiO2 particles were characterized by FTIR, SEM and XRD techniques. The results showed that vinyl triethoxysilane has been successfully grafted onto SiO2 particles and basically there are no changes in the size of SiO2 particles before and after the modification by vinyl triethoxysilane. XRD results show that the synthesized SiO2 particles have certain crystallinity.

Influence of hydrophobic characteristic of organo-modified precursor on wettability of silica film

The objective of this study is to design new hybrid silica materials as templates with hydrophobic properties, prepared at room temperature by a base catalyzed sol–gel process. As silica sources, organoalkoxysilanes functionalized with short hydrophobic chains were used: tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES), vinyltriethoxysilane (VTES), octyltriethoxysilane (OTES) and isobutyltriethoxysilane (iTES). It was shown that hydrophobicity of the functionalized silica nanoparticles increased as a function of length of the aliphatic chains (MTES < iTES < OTES) or when, instead of a hydrophobic alkyl chains (substituting group of silica precursors), a monounsaturated group was used (VTES). It was observed that the samples responded in a specific way to each type (hydrophilic or hydrophobic) of the dropped liquid. Even though the experiments were limited to short hydrocarbon chains, they showed that there is a threshold to reach high hydrophobicity of the hybrid surface.

Investigation of polyethylene/sisal whiskers nanocomposites prepared under different conditions

In this work, sisal nanowhiskers (SNWs) extracted from sisal fibers were used to reinforce high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE). The nanocomposites were prepared by solution casting from toluene and melt mixing, both followed by melt pressing. In the case of melt mixing, the surfaces of the SNW were also chemically modified with 1 phr of vinyl triethoxy silane to improve their dispersibility and compatibility with the matrices. The SNW had an average length of 197 nm and diameter of 12 nm, and a crystallinity index of 89%. Fourier transform infrared confirmed the surface chemical modification of the SNW. The whiskers were fairly well dispersed in the matrices, regardless of the treatment or preparation method. The presence of whiskers, as well as nanocomposite preparation method, had an observable influence on the storage modulus of LDPE, but very little influence on that of HDPE. There was, however, no significant influence on the degradation behavior of both polymers. The crystallization behavior of the polymers was found to strongly depend on their morphologies. The melting and crystallization behavior of the LDPE nanocomposites were almost unchanged, while an increase in crystallinity was observed for all the HDPE nanocomposites. The tensile properties depended on the type of polymer, the treatment, and the preparation method. Generally there was an improvement in tensile modulus, and a decrease in elongation at break, but the stress at break only improved for the HDPE nanocomposites. POLYM. COMPOS., 35:2221–2233, 2014. © 2014 Society of Plastics Engineers

Preparation of bifunctionalized phenylene-bridged periodic mesoporous organosilica for solid-phase microextraction

Well-ordered bifunctionalized periodic mesoporous organosilicas (BPMOs), with various mesostructures (like hexagonal p6mm, cubic Iad symmetry), relatively large mesopores, a phenylene-bridged skeleton and vinyl functional groups, were first prepared by co-condensation of 1,4-bis(triethoxysilyl)benzene (BTEB) and triethoxyvinylsilane (TEVS) with a triblock copolymer (P123) as a template under acid conditions. It was found that the mesostructure of the BPMOs can be facilely tuned by altering the fraction of organosilanes in the synthesis mixture. With an increase of TEVS content, the mesostructure changed from p6mm to Iad, until disordered. The mechanisms of the mesophase transformation were discussed based on the adsorption of vinyl groups into the micelles and the relative reactivities of the organosilane precursors. In addition, the potential application of the BPMOs as an effective fibre-coating absorbent is tested in solid-phase microextraction (SPME) analyses.

Thermal and mechanical properties of functionalized mullite reinforced unsaturated polyester composites

This work studies the development of varying weight percentages (0.5, 1.0, and 1.5 wt%) of surface functionalized mullite reinforced unsaturated polyester (UP) composites and their thermal, dielectric, water absorption, and mechanical properties. The synthesized mullite was functionalized with vinyltriethoxysilane (VTES). The introduction of vinyl groups on the surface of mullite was confirmed by FT‐IR, TGA, and X‐ray diffraction (XRD) analyses. Varying weight percentages (0.5, 1.0 and 1.5 wt%) of vinyl functionalized mullite (VFM) were incorporated into UP resin with a benzoyl peroxide initiator to obtain composites. The resultant data obtained from thermal, mechanical, dielectric, and water absorption studies, indicate that incorporation of VFM, leads to a significant improvement in the thermo mechanical, dielectric, and moisture resistant properties of the UP composites, compared with those of neat UP matrices. The molecular dispersion of VFM fiber in reinforced UP matrix composites was confirmed by SEM analysis. POLYM. COMPOS., 35:1663–1670, 2014. © 2013 Society of Plastics Engineers

Facile formation of superhydrophobic silica-based surface on aluminum substrate with tetraethylorthosilicate and vinyltriethoxysilane as co-precursor and its corrosion resistant performance in corrosive NaCl aqueous solution

A facile sol–gel method has been developed to create a superhydrophobic surface on aluminum substrate with tetraethylorthosilicate (TEOS) and vinyltriethoxysilane (VTES) as co-precursor at room temperature. Firstly, nanometer sized silica particles were self assembled on the substrate through the hydrolysis of TEOS. Then, the silica particles were modified with vinylsiloxane through the hydrolysis and condensation polymerization of VTES. The emphasis was focused on investigating the influence of the molar ratio between NH3·H2O and ethanol on the surface morphology and wetting property. The surface morphology was observed by scanning electron microscopy (SEM), the chemical composition and bonding state of the surface were explored by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS), and the wetting property of the surface was investigated by water contact angle measurement (WCA). The modified silica-based surface possessed the greatest static contact angle of 154.9°, exhibiting excellent superhydrophobic property. A hierarchical microstructure with spherical microparticles of around 2μm decorated with nanoparticles of around 450nm was observed on the film surface. The surface was covered by hydrophobic vinyl groups via the decoration of silica microparticles with vinyl-terminated siloxane nanoparticles as evidenced by EDS, FTIR and XPS. The corrosion resistant performance and durability of the superhydrophobic silica-based surface formed on aluminum substrate in corrosive NaCl solution were estimated by electrochemical impedance spectroscopy (EIS) measurements. The appropriate equivalent circuit model was put forward to fit and analyze the EIS data. The electrochemical result revealed that the corrosion resistant performance of aluminum was improved greatly by the superhydrophobic treatment.

Effect of vinyltriethoxysilane addition on the pyrolytic conversion of tetraethoxysilane based silica gel

The effect of vinyltriethoxysilane (VTES) addition on the pyrolytic conversion of tetraethoxysilane (TEOS) based silica gel had been studied. Thermogravimetric analysis coupled with mass spectroscopy was carried out to study the thermal decomposition behavior of precursor gels. The ceramic yield of precursor gels was decreased with the increase of the VTES content. 29Si magic angle spinning nuclear magnetic resonance indicated that the incorporation of VTES into TEOS not only changed the composition and structure of precursor gels, but also increased carbon-enriched SiOxC4−x units of silicon oxycarbide ceramics during the pyrolysis conversion. The carbon content of SiOC ceramic was almost unchanged between 1,000 and 1,500 °C. However, the O/Si ratio of the silicon oxycarbide ceramic was reduced and the free carbon content was increased with the increasing molar ratios of VTES/TEOS. Moreover, the carbothermal reduction reaction led to the free carbon content decreased with the increase of the sintering temperature.

AFM study of the vinyl triethoxysilane (A-151) film prepared by spraying deposition and dipping deposition

The vinyl triethoxysilane (A-151) film was prepared by the spraying deposition and dipping deposition technique. The surface topography and growth behavior of A-151 films was investigated by using atomic force microscopy (AFM) and static water contact angle measurements. The results indicate that the topography was strongly affected by the treatment conditions. The surface topography of silane film was changed from the islands morphology to the network morphology with the increasing temperature of SiO2 substrate, and the larger self-polymerized silane aggregation will be formed by using the ultrasonic technology. The hydrophobicity of the SiO2 substrate was improved after A-151 deposition.

Extrinsic surface scattering and intrinsic absorption loss of vinyl based hybrid organic–inorganic materials for optical waveguides applications

Hybrid photosensitive materials were prepared by using vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBu) precursors through sol–gel technique. The materials are intended for optical telecommunication applications. Thus, high optical transmissions at the second and third optical telecommunication windows are essential. Extrinsic surface scattering due to surface roughness and intrinsic absorption due to aliphatic CH and OH groups are always ascribable to the optical power attenuations at aforementioned optical telecommunication windows. Optical waveguide based on hybrid sol–gel materials were fabricated, characterized and analyzed in order to investigate the extrinsic and intrinsic sources of attenuation and their contributions. The fabricated samples were characterized for propagation loss, surface condition, and Fourier transform IR (FTIR) absorption spectra. Propagation loss were measured by means of cut-back method as 1.6 and 6.9dB/cm at 1310 and 1550nm wavelengths, respectively. Surface scattering loss was modeled based on measured rms roughness of 0.724nm and turned out to contribute less than 0.01% of the total propagation loss. FTIR absorption spectra show the persistent existence of aliphatic CH and OH groups within the final hybrid sol–gel materials.

An aptamer-based biosensor for sensitive thrombin detection with phthalocyanine@SiO2 mesoporous nanoparticles

Silica nanoparticles, with entrapped hydrophobic photosensitizer tetra-α-(2, 4-di-tert-butylphenoxy)-phthalocyaninato zinc (ZnPc(OAr)4), were synthesized by hydrolyzing triethoxyvinylsilane (TEVS) and 3-amino propyl triethoxysilane (APTES). The as-prepared nanoparticles, which were highly monodispersed spheres (about 100nm), exhibited strong Q-band absorption of ZnPc(OAr)4 centered at 701nm. The aqueous solubility of ZnPc(OAr)4 encapsulated in silica nanoparticles was obviously improved. The nanoparticles efficiently generated singlet oxygen (1O2) both in organic and aqueous solutions after being irradiated at suitable wavelength. The resulting 1O2 then initiated chemiluminescence (CL) by reacting with a methyl cypridina luciferin analog (MCLA). Based on the photoinduced CL, a sensitive aptamer-based sandwich-type sensor was presented to detect human thrombin. Thrombin was first attached to Pc@SiO2 via secondary aptamer, and then they were collected, for CL determination, by beads with primary aptamer. The proposed approach, which was highly selective with a low detection limit of 80pmol/L, minimized the nonspecific adsorption. Such an aptamer-based biosensor is feasible in screening biomarkers in complex matrices at ultratrace levels.

On the structural and physicochemical properties of gamma irradiated UHMWPE/silane hybrid

This study has been carried to investigate the influence of gamma rays on the structural and physicochemical properties of UHMWPE/silane hybrid. UHMWPE was mixed with vinyltriethoxysilane (VTES) and compression molded sheets were irradiated at different doses of gamma rays. Fourier transform infrared spectroscopy indicated the formation of siloxane linkages in hybrids, which were found to be shifted towards lower wave number upon irradiation. The X-ray diffraction patterns showed significant increase in the percentage crystallinity of hybrid upon gamma irradiation, especially at 65 kGy absorbed dose. Scanning electron micrographs showed good consolidation and compaction with no surface defects. Moreover, the rough topography was changed to smooth ripple-like appearance upon γ-irradiation. Thermal analysis revealed that irradiated hybrids exhibited higher onset thermal degradation temperature, peak melting temperature, and crystalline lamellae thickness compared with the water treated hybrid. In addition, the tensile testing confirmed an increase of 41% and 133% in yield strength and Young's modulus in 100 kGy irradiated hybrid respectively than that of water treated hybrid. We hope that the irradiated UHMWPE/silane hybrids can be used in various high-strength applications such as total joint replacements, pickers for textile machinery, lining for coal chutes and dump trucks.

Study of the silane modification of magnesium hydroxide and their effects on the flame retardant and tensile properties of high density polyethylene nanocomposites

The modification of magnesium hydroxide (MH) with triethoxy vinyl silane (TVS) was carried out via three different methods and the results are discussed with respect to their effect on the flame retardant and the tensile properties of high density polyethylene (HDPE) nanocomposites. Via a xylene suspension of MH and TVS, via a water suspension of MH and TVS, and via powder mixing of MH and TVS. It was found that in all three cases, SiOMg bonds formed on the MH particles surface. Also, this silane modification induced a certain level of particle agglomeration, but without modifying their morphology or particle size. It was also found that the flame retardant properties of the HDPE nanocomposites did not improve because of the use of silane modified MH. During the flame retardant tests, all nanocomposites passed the UL-94-HB, but it was observed that the flame permanence time was longer when using modified MH. The tensile properties were negatively affected by the addition of unmodified MH; the nanocomposites became hard and brittle, with reduced flexibility. This negative effect was diminished when using silane modified MH. POLYM. COMPOS., 35:1060–1069, 2014. © 2013 Society of Plastics Engineers

Effect of woody biomass surface free energy on the mechanical properties and interface of wood/polypropylene composites

The aim of this study is to investigate the effect of surface free energy of wood flour (WF) and silanized WF on the mechanical properties and interface of wood/polypropylene (PP) composites. The contact angles of three probe liquids against unmodified and modified spruce WF were tested by capillary rise method based on the Washburn equation. Then the surface free energy and its corresponding dispersion and polar components were calculated according to the method developed by Owens–Wendt–Kaelble. The tensile strength and flexural strength of the wood/PP composite samples made with unmodified and modified WF were tested and the flexural fracture surfaces were analyzed by scanning electron microscopy (SEM). The results showed that the surface free energy of WF increased from 26.0 to 36.1 mJ/m2, which was higher than that of PP (29.4 mJ/m2), and its corresponding polar component decreased from 13.1 to 4.4 mJ/m2, and the dispersion component increased from 12.9 to 31.7 mJ/m2 after the modification with 4 wt.% vinyltriethoxy silane, which makes it possible for spreading of PP on the surface of WF, the tensile strength and flexural strength of wood/PP composites made with modified WF were obviously improved. In addition, the improved compatibility between WF and PP was well confirmed by SEM.

Tunable wettability of monodisperse core-shell nano-SiO2 modified with poly(methylhydrosiloxane) and allyl-poly(ethylene glycol)

In this paper, vinyl-capped silica nanoparticles (V–SiO2) were first synthesized from tetraethyl orthosilicate (TEOS) and vinyltriethoxysilane (VTEOS). Then the V–SiO2 nanoparticles were modified with poly(methylhydrosiloxane) (PMHS) and allyl-poly(ethylene glycol) (APEG) to form core-shell hybrid particles V–SiO2/PMHS/APEG, which showed tunable wettability as well as uniform monodispersity in ethanol and toluene. Particularly, V–SiO2/PMHS/APEG samples with moderate wettability could be served as emulsion stabilizer for silicone oil–water system. The modified particles were characterized by static contact angle (CA), Fourier transform infrared (FT-IR) spectroscopy, FT–Raman spectroscopy, 29Si CP MAS NMR, thermal analysis (TGA), transmission electron microscopy (TEM) and particle size distribution. FT-IR, FT–Raman and 29Si CP MAS NMR demonstrated that PMHS together with APEG was chemically anchored to the surface of nano-SiO2. Deduced from static contact angle, strong hydrophobicity (CA=157.76°) could be achieved for V–SiO2/PMHS particles (m(PMHS):m(V–SiO2)=1:1), while V–SiO2/PMHS/APEG samples exhibited moderate wettability (CA=89.20°) when the mass ratio of V–SiO2, PMHS and APEG was conducted at 1:1:6.0. Thermal analysis (TGA) showed that the grafting yield of PMHS and APEG was 5.76×10−5 and 6.13×10−4mol/g, respectively. V–SiO2/PMHS/APEG samples displayed superior monodispersity in both ethanol and toluene, and the mean diameter was 245.5nm, revealed from particle size distribution. Furthermore, digital photos, optical micrographs and emulsion drop size distribution demonstrated that silicone oil/water emulsions were successfully stabled by the core-shell hybrid particles V–SiO2/PMHS/APEG.

Functional processing of PET fabrics using boehmite/silica/thiazole dye hybrid materials

A series of hybrid materials composed of boehmite/silica/thiazole dyes and prepared via the sol-gel process is synthesized from aluminum isopropoxide (AIP) and tetraethoxysilane using heteroaryl 2-amino-thiazole azo dyes. Heterocyclic 2-amino-thiazole azo dyes undergo a hydrolysis-condensation reaction with an appropriate proportion of AIP under a catalyst, at a constant ratio of vinyltriethoxysilane (VTES) and tetraethoxysilane (TEOS). The structures of these hybrid materials composed of boehmite/silica/thiazole dyes are characterized using Fourier transform infrared (FT-IR) analysis. The surface morphology of polyethylene terephthalate (PET) fabrics is evaluated using scanning electron microscopy (SEM). SEM images show uniform dyeing of the PET fabrics that confirms the reaction of the hybrid materials with the PET fabrics. The water contact angle, washing fastness, color evenness, air permeability, and warmth retention of the PET fabrics dyed with hybrid materials composed of boehmite/silica/thiazole dyes are evaluated. The evaluation results indicate improved warmth retention property and good water repellency.

Preparation and characterization of a novel nanocomposite particles via in situ emulsion polymerization of vinyl functionalized silica nanoparticles and vinyl acetate

A new class of poly(vinyl acetate) (PVAc)/silica nanocomposite particles was successfully prepared in aqueous solution through a facile synthetic process. First, vinyl functionalized silica nanoparticles (VFSs) were synthesized using one-step method in aqueous emulsion, and then the vinyl groups located on the surface of VFSs were used to induced in situ polymerization of vinyl acetate. Scanning electron microscopy (SEM) images showed that VFSs and PVAc/silica nanocomposite particles all revealed highly monodispersed and uniform spheres. Especially, PVAc/silica nanocomposite particles obtained from transmission electron microscopy images presented an obvious core–shell structure, and the thickness of PVAc shell grafting on the surface of VFSs core was about 17 nm. In addition, the influence of the hydrolyzed and condensed time of vinyl triethoxysilane on the size and size distribution of VFSs was also investigated. The results of dynamic light scattering and SEM analysis indicated that the size and size distribution of VFSs decreased gradually with the extension of the reaction time from 6 to 48 h. Moreover, the structures and thermal properties of the samples were characterized via FT-IR and heat-flow DSC–TG.

Fluorescent and laser properties of pyrromethene 567 (PM567) doped into multi-precursors derived gel glasses

In this work, the laser dye PM567 was incorporated into various organically modified silicate gel glasses (ORMOSILs) derived by methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) precursors mixed in various ratios. The laser performances of PM567 doped into MTES–VTES-derived ORMOSILs including the laser slope efficiency, threshold and lifetime together with the spectroscopic properties were investigated. Blue-shifts of fluorescent peaks, extended fluorescent lifetime, improved laser efficiency and lifetime of PM567 doped into ORMOSILs derived by mixed precursors of MTES and VTES have been observed, which might related to the microstructures and micro-chemical environment of the dye in ORMOSILs.

Preparation and characterization of a novel fluoro-silicone acrylate copolymer by semi-continuous emulsion polymerization

A novel fluoro-silicone acrylate (FSA) copolymer latex was synthesized with 2-acrylamido-2-methyl-propanesulfonic acid (AMPS), which served as a polymerizable emulsifier by semi-continuous emulsion polymerization. Methyl methacrylate (MMA), butyl acrylate (BA) and 1,3,5-trimethyltris (3,3,3-trifluoropyropyl) cyclotrisiloxane (D3F) were served as co-monomers while vinyltriethoxysilane (VTES) was used as a cross-linking agent. The structure and surface morphologies of the copolymer were characterized by FT-IR, 1H NMR, TEM, TGA and DSC. The influences of AMPS, D3F and VTES on the copolymer's properties of appearance, conversion rate, gel rate and solid content were discussed. The analytical results indicated that the FSA copolymer latex had a narrow particle size distribution around 100nm with high temperature stability. The copolymer latex shows excellent water repellency with the contact angles of cotton and silk textile of 125.8° and 120.7°, respectively.

Hybrid polymeric latexes containing magnetite

The work describes a study for preparing polystyrene (PSt) and polymethyl methacrylate (PMMA) latex, containing magnetite (Fe3O4), covalently bounded to the polymeric chains. The magnetite was functionalized with various alkoxysilanes containing double bonds: vinyltriethoxysilane (VTES), methacryloyl propyl trimethoxysilane (MPTS) and vinyldimethylethoxysilane (VMe2TES). The ferrite-silane composite forms higher average size particles with MPTS than with VTES. Ferrite functionalized with VMe2TES forms stable latexes with both PSt and PMMA polymers. PSt forms also stable latexes with ferrite functionalized with VTES but unstable with ferrite functionalized with MPTS.

Synthesis of VTES/SBA-15 Prepared by Post-Grafting: XRD Characteristics on the Effect of Calcination Properties

Functionalization of Santa Barbara Amorphous-15 (SBA-15) with vinyltriethoxysilane (VTES) via post-grafting method has been synthesized with the effect of calcination time span and temperature range. X-ray powder diffraction has been a means to evident the incorporation of VTES functional groups and to characterize the peak diffraction pattern. The samples of parent SBA-15 have been treated in different calcination temperature and time, ranging from 400°C to 800°C and 2 hr to 8 hr, respectively. The XRD results show that two dimensionalp6mmof high order hexagonal mesoscopic structure of VTES/SBA-15 could not be retained at higher temperature of calcination than 700°C. However, the higher time spans of calcination up to 8 hrs preserve the long-range order of functionalized SBA-15.