Vinyltriethoxysilane Research Articles

Physical properties and morphology of siloxane–polyacrylate dispersion and coating films

The aim of this work was to study the morphology and physical properties of siloxane–polyacrylate (SPA) dispersion and coating films. The SPA dispersion was synthesized by seeded emulsion polymerization using two different types of silane coupling agents, i.e., vinyltriethoxysilane (VTES) and 3-(trimethoxysilyl) propyl methacrylate (MPTMS), at 1–9% by weight. The effect of the type and content of silane coupling agent used in the SPA dispersion synthesis on the resulting morphology and physical properties of the obtained SPA dispersion and coating films were studied. The results revealed that SPA dispersion synthesized using VTES exhibited a smaller particle size and a higher stability than those using MPTMS. Furthermore, the hydrophobic surfaces and water repellence of the coating films using VTES in the emulsion were higher than those using MPTMS, due to the smoother surface morphology.

Membrane distillation of pesticide solutions using hydrophobic track-etched membranes

In connection with the widespread use of pesticides, the question arose of their possible danger to humans and the environment. The danger of using pesticides can be associated with the presence of residues in food products, with the pollution of water bodies, soil and other objects. Therefore, water treatment from pesticides is a major environmental task. In this study, the hydrophobic poly(ethylene terephthalate) (PET) track-etched membranes (TeMs) obtained by graft polymerization of triethoxyvinylsilane (TEVS) and covalent attachment of 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (PFDTS) were tested in the water treatment from a pesticide (carbendazim) using direct contact membrane distillation. Hydrophobic PET TeMs were characterized by scanning electron spectroscopy, Fourier-transform infrared spectroscopy, liquid entry pressure analysis. The hydrophobization of PET TeMs led to a rapid increase in the contact wetting angle and reached to 134°. The efficiency of water purification from carbendazim was evaluated by water-flux measurements and ultraviolet–visible (UV–Vis) spectroscopy. The carbendazim solution was used at a concentration of 5, 10 and 20 mg/l. The largest permeate flux of hydrophobized membranes was 214 g/m2 h. Concentration of carbendazim in permeate solution was less than 100 µg/l.

Effect of Laser Treatment and Hydrophobization on the Corrosion-Electrochemical Behavior of Aluminum

The effect of laser treatment of aluminum samples on the properties of the surface hydroxide oxide layer is studied. It is shown that treatment in air leads to an increase in the thickness of the oxide layer and the almost complete disappearance of hydroxide forms, which results in deterioration of the protective properties of this layer due to its higher defectiveness and porosity. It is found that the optimal treatment regime for aluminum, the surface of which is covered by an oxide layer with a significant fraction of hydroxides, is laser irradiation in an inert argon gas medium with small (1–2 vol %) oxygen content. Laser treatment leads to the formation of a protective surface layer that effectively inhibits the anodic dissolution of aluminum in a model corrosion medium, borate buffer solution at pH 7.4. It is shown that the initial hydroxide oxide film and the oxide film formed during laser treatment processing are hydrophilic, that is, they are well moistened with water. The surface treatment of aluminum in the initial state and after laser irradiation with a solution of vinyltriethoxysilane (VTES) leads to the formation of a hydrophobic adsorption layer and a significant decrease in the currents of anodic dissolution. Using X-ray photoelectron spectroscopy, it is shown that silane adsorption occurs both with the participation of silicon atoms and carbon atoms of an alkene bond. The hydrophobic layer of adsorbed silane on the laser-treated surface has a greater thickness and has a higher inhibiting effect on the anodic dissolution of aluminum than in the case of the initial aluminum surface.

Performance of Modified Nano-SiO2 Composite Phosphating Coating on the Surface of Steel

In order to enhance the corrosion resistance and the quality of the phosphating film, nano-SiO2 was used in the phosphating solution.The structure and properties of the phosphating film were evaluated by SEM, electrochemistry, cupric sulfate drop corrosion test and film thickness measurement.The results show that the thickness of the phosphating film increases with the increase of nano-SiO2 content. The nano-SiO2 modified with vinyl triethoxy silane possessed good dispersibility in the phosphating solution, the phosphating solution with the addition of modified nano-SiO2 could greatly improve the corrosion resistance of the phosphating film.

Controlling the size of silica nanoparticles in filler nanomatrix structure of natural rubber

In the present work, size of silica nanoparticles in filler nanomatrix structure was controlled by graft-copolymerization of vinyltriethoxysilane (VTES) onto deproteinized natural rubber (NR) after NR was grafted with styrene to prepare NR-g-Sty-g-VTES. The structure of NR-g-Sty-g-VTES was characterized by FT-IR and NMR spectroscopy. It was demonstrated that the silica nanoparticles and polystyrene (PS) were successfully formed in natural rubber. The morphology of silica nanoparticle in the samples were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was observed that very small silica nanoparticles, about 60 nm, were generated in NR-g-Sty-g-VTES. The tensile strength of NR-g-Sty-g-VTES was found increasing 7 times, that is from 3 MPa for NR to 20 MPa for NR-g-Sty-VTES. Storage modulus and loss modulus for NR-g-Sty-g-VTES were found remarkably increasing 20 and 25 times as those for NR, respectively. The formation of well-controlled silica nanoparticle in the nanomatrix was proved to bring about the superior properties for NR material.

Bioactive moist bionanocellulose-based wound dressing material

This work presents the results of our studies on the bionanocellulose (BNC)-based hybrid materials designed to potentially serve as an innovative bioactive moist dressing for the treatment of difficult-to-heal wounds occurring in diabetics. We have particularly focused on modification of the membranes’ surfaces by developing the methodology of the covalent attachment of biologically active substances (insulin and heparin) on one side of the BNC-based membrane and deposition of the silicone protection layer on the opposite side. The silicone layer on the BNC-substrate was obtained using two types of precursors (vinyltriethoxysilane (VES) and allyltrimethoxysilane (ATMS)). Its successful formation was confirmed by means of FTIR and SEM techniques. That modification ensures an effective protection for BNC against drying out as demonstrated by contact angle measurements as well as carrying out the swelling and drying tests. Insulin and heparin were then covalently attached to the unmodified side of previously obtained materials as confirmed utilizing XPS and appropriate colorimetric tests: Coomassie Brilliant Blue and Azure A, respectively. Moreover, it was revealed in in vitro biological study that the generation of a silicone layer has no negative effect on adhesion, proliferation and morphology of mouse embryonic fibroblasts (MEF) cultured on the surface of developed materials.

Silicone acrylate dispersion based on semi-continuous seed emulsion polymerization using polymerizable emulsifiers

The silicone modified acrylate dispersion was successfully prepared by semi-continuous seed emulsion polymerization, in which methyl methacrylate (MMA) was used as a hard monomer, butyl methacrylate (BA)was used as a soft monomer, and a double bond-containing polymerizable emulsifier ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86)and potassium persulfate (KPS)were utilized as emulsifiers and initiators, respectively. A functional monomer, benzyl methacrylate (BZMA), and a modified monomer, vinyltriethoxysilane (VTES), were introduced into the base dispersion. The factors, which have an influence on emulsion polymerization performance, were optimized. At the same time, the dispersions prepared with conventional emulsifiers and polymerizable emulsifiers were compared under the same conditions. The structure and properties of the synthetic dispersion were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA). The results showed that the optimum preparation conditions of the dispersion are as follows: The amount of emulsifier was 3%, the amount of initiator was 0.5%, main monomer ratio was 1:1, the amount of functional monomer BZMA and VTES was 3%, respectively. The dispersion obtained by using DNS-86 had better thermal stability, chemical stability and the dispersion was uniformly blue, which represented small particle size. After modification, the film showed higher hydrophobicity.

Synthesis of mechanically durable superhydrophobic polymer materials with roughness-regeneration performance

Although superhydrophobic materials play important roles in emerging fields because of their anti-wetting behavior, they still face a series of challenges such as brittle rough structure. Herein, a mechanically durable superhydrophobic polymer material (SPM) with roughness-regenerative characteristics was synthesized by integrating acrylate-terminated polyurethane (A-PU) with precipitated silica particle (PSP) using vinyltriethoxysilane (VTES) as a bridge. With the optimization of UV curable components, the appropriate covalently cross-linking networks and hierarchical rough structure were formed in the polymer skeleton, endowing the SPM with solid mechanical strength (B hardness) and superior superhydrophobicity (CA > 152°, SA < 5°). Taking advantage of the roughness-regenerative characteristics across the material bulk, the SPM was capable of surviving after multi-cycle abrasion damages (>250 cycles). More importantly, the roughness-regenerative characteristics enabled the damaged SPM to repair its superhydrophobicity via sanding treatment (>40 cycles). Our findings convincingly propose a feasible approach to fabricate versatile superhydrophobic materials as promising candidates for emerging fields.

Free-radical graft polymerization of acrylonitrile on gamma irradiated graphene oxide: Synthesis and characterization

A novel graphene oxide (GO) grafted polyacrylonitrile (PAN) nanohybrid was synthesized via free radical polymerization. An innovative green method has been used to modify the surface of graphene oxide by gamma radiation. GO was gamma irradiated in air at different absorbed doses to enhance the amount of oxidative groups on its surface. The gamma irradiated GO was silanized with vinyltriethoxysilane (VTES) and used as base material to graft acrylonitrile (AN) on its surface. Synthesis parameters were optimized by varying the concentration of monomer, initiator, and surfactant to get maximum grafting of PAN. The percentage of grafting on GO was increased with increase in gamma absorbed dose. Maximum grafting of 850% of PAN was obtained in 100 kGy irradiated GO. Spectroscopic techniques such as FT-IR, Raman and XRD were used to characterize the synthesized nanohybrids. The obtained results confirmed the structural changes during gamma irradiation of GO and successful grafting of PAN onto it. The morphological changes in irradiated GO during silanization and its PAN grafted nanohybrids were studied by field emission scanning electron microscopy (FESEM). Thermal gravimetric analysis (TGA) demonstrated that the thermal stability of GO-g-PAN was decreased with increase in PAN content. The developed nanohybrid can act as a precursor for the development of new materials.

Multifunctional, CD44v6-Targeted ORMOSIL Nanoparticles Enhance Drugs Toxicity in Cancer Cells.

Drug-loaded, PEGylated, organic-modified silica (ORMOSIL) nanoparticles prepared by microemulsion condensation of vinyltriethoxysilane (VTES) were investigated as potential nanovectors for cancer therapy. To target cancer stem cells, anti-CD44v6 antibody and hyaluronic acid (HA) were conjugated to amine-functionalized PEGylated ORMOSIL nanoparticles through thiol-maleimide and amide coupling chemistries, respectively. Specific binding and uptake of conjugated nanoparticles were studied on cells overexpressing the CD44v6 receptor. Cytotoxicity was subsequently evaluated in the same cells after the uptake of the nanoparticles. Internalization of nanocarriers loaded with the anticancer drug 3N-cyclopropylmethyl-7-phenyl-pyrrolo- quinolinone (MG2477) into cells resulted in a substantial increase of the cytotoxicity with respect to the free formulation. Targeting with anti-CD44v6 antibodies or HA yielded nanoparticles with similar effectiveness, in their optimized formulation.

Functionalized Ordered Mesoporous Silica by Vinyltriethoxysilane for the Removal of Volatile Organic Compounds through Adsorption/Desorption Process

An organic–inorganic hydrophobic mesoporous silica has been successfully prepared by a co-condensation method with tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) as mixed precursors under...

Synergistic enhancement of vinyltriethoxysilane and layered Mg–Al double hydroxide on the tracking and erosion resistance of silicone rubber

It is of great significance and challenge to efficiently improve the tracking and erosion resistance of silicone rubber along with the growing requirements in the field of outdoor high voltage insulation. In this work, we herein proposed an effective way to address this issue by incorporating vinyltriethoxysilane (ViTES) and layered Mg–Al double hydroxide (LDH) into high temperature vulcanized silicone rubber (HTVSR). ViTES/LDH notably enhanced the tracking and erosion resistance of HTVSR. With addition of 3.33 phr ViTES and 5.00 phr LDH, the anti-tracking performance of HTVSR reached the 1A 4.5 level, and the eroded mass was merely 0.3%. The results of scanning electron microscopy and equilibrium swelling showed that ViTES substantially improved the interfacial interaction between HTVSR and LDH and the crosslinking density of HTVSR, and enhanced the dispersion of LDH sheets in the HTVSR matrix. The possible synergistic suppression mechanism of ViTES/LDH on the tracking and erosion of HTVSR was further studied and demonstrated by the plasma irradiation analysis, thermogravimetry and thermogravimetry-Fourier transform infrared spectrometry. It was indicated that under the high voltage arcing discharge, LDH facilitated the formation of a dense barrier layer consisting of bimetal mixed oxides on the HTVSR surface, exerting outstanding lamellar barrier effect. The further degradation and the generation as well as development of electrical tracking were efficiently suppressed. Our findings provided a new approach to fabricate silicone rubber with excellent tracking and erosion resistance.

Emulsion Copolymerization of Vinyl Acetate and Vinyl Silanes: Kinetics and Development of Microstructure

AbstractThe batch emulsion copolymerization of vinyl acetate with different vinyl silane functional monomers (vinyl trimethoxysilane [VTMS], vinyl triethoxysilane [VTES], and vinyl silanetriol [VSTO]) is studied. The nature of the silane strongly affects the development of the microstructure and crosslinking ability of the latexes. A combination of techniques (Soxhlet extraction, centrifugation, assymetric‐flow field flow fractionation AF4/MALS/RI) shows that the factor controlling the molar mass and crosslinking density is the degree of hydrolysis of the alkoxysilane, producing higher molar masses and degrees of crosslinking when the degree of hydrolysis is high. Thus, the copolymer containing VSTO produced a very crosslinked latex, the one with VTMS produced a latex with a low degree of crosslinking in the wet state that can yield high degrees of crosslinking upon drying, and the latex with VTES do not produce significant amounts of crosslinking neither before nor after drying.

Isothermal cold crystallization kinetics and properties of thermoformed poly(lactic acid) composites: effects of talc, calcium carbonate, cassava starch and silane coupling agents

The effects of three different fillers (i.e., talc, calcium carbonate, and cassava starch) and surface functionalization by 3-aminopropyltriethoxysilane (APTES) and vinyltriethoxysilane (VTES) on morphology, thermal and tensile properties of the poly(lactic acid) (PLA) composites were comparatively examined. Dynamic differential scanning calorimetry (DSC) results revealed that the incorporation of filler can facilitate the cold crystallization of PLA, as confirmed by lowered cold crystallization temperature. By fitting DSC data with Avrami model, the highest isothermal cold crystallization rate constant k and the shortest crystallization half time t1/2 were obtained for the PLA/talc composites under isothermal temperature of 100 °C, implying that talc was the most effective nucleating agent for PLA in this study. The average Avrami index n of neat PLA and its composites lay within the same range of 3.0–3.6, which reflected the three-dimensional spherulitic growth of PLA with the mixture of instantaneous nuclei and sporadic nuclei. In comparison with the composite cast films, the thermoformed films had higher degree of crystallinity as well as higher tensile strength and Young’s modulus owing to the chain orientation upon annealing. Furthermore, the addition of silane-treated talc, especially APTES-treated talc, fastened cold crystallization rate and enhanced tensile properties because of the improved interfacial interaction between talc particles and PLA matrix.

Composite based on poly(acrylic acid)/modified attapulgite/zinc oxide as a flame retardant of cotton fabrics

Poly(acrylic acid)/modified attapulgite/zinc oxide composite (PAA/BF-ATP/ZnO) was prepared by acrylic acid, modified attapulgite (BF-ATP), triethoxy vinyl silane modified ZnO using in situ polymerization, and used in cotton fabric for improving the flame-retardant and UV protection properties. FT-IR and TEM results showed that PAA/BF-ATP/ZnO composite was successfully prepared. The stability, percent conversion, solid content and rotational viscosity of the composites with different ZnO content were investigated. The results showed that the conversion of composites was all above 98%, and these composites also had good stability, when the content of ZnO was 0.2–1%. Composite was loaded onto the cotton fabric by the dip-pad-dry method. The results showed that the thermal and flame retardant properties of cotton fabric were improved after treatment with the PAA/BF-ATP/ZnO, the LOI of the cotton fabrics with PAA/BF-ATP/ZnO was reached to 24.4%, which was 1.3% higher than that of PAA/BF-ATP treated cotton fabric. The burning rate was reduced to 0.68 mm/s, which was 0.24 mm/s lower than that of PAA/BF-ATP treated cotton fabric.

Preparation of Fluorine/Silicon Co-Modified Elastic Acrylate with Low Fluorine and High Performance

The methyl acrylate was modified with hexafluorobutyl methacrylate (G02) and vinyl triethoxy silane (A-151) as modified monomers, Methyl Methacrylate (MMA) as hard monomer and Butyl Acrylate (BA) as soft monomer. Pre-emulsification, seed emulsion and semi-continuous synthesis process were adopted to the effects of the preparation process, the ratio of G02 and A-151 modified monomers, the amount of soft monomer and hard monomer on product performances. The structure of the modified acrylate was characterized by infrared spectroscopy (FTIR). The thermal stability of the product was determined by the Thermo Gravimetric Differential Thermal Analyzer (TG-DTA). It was showed that the water absorption of the paint film prepared by using the optimized formula was 5.1%, the adhesion of the surface layer of the tinplate was grade 1, the tensile strength of the latex film layer was 2.13 MPa and the elongation of the high elastic resin was 736%. The organic fluorine-silicon and monomers were successfully grafted onto the acrylic polymer, the low fluorine high performance fluorine/silicon co-modified elastomeric acrylate was successfully prepared. Compared with other silicone and fluorine modified acrylate, the product has better thermal stability and tensile strength, improved cost-effectiveness of this type of exterior coating.

Surface modification of aqueous miscible organic layered double hydroxides (AMO-LDHs).

Silane modification of layered double hydroxides (LDHs) plays an important role in controlling the surface hydrophobicity and improving the compatibility of LDHs dispersed in non-polar materials. However, the surface modification of conventional LDHs in hydrous conditions typically results in aggregated particle morphologies, low surface areas and accessible pore volumes. In this study, well dispersed and high surface area silane grafted AMO-Zn2MgAl-CO3 LDH were prepared using the silane coupling agents (triethoxyvinylsilane (TEVS), triethoxyoctylsilane (TEOS) and (3-glycidyloxypropyl)trimethoxysilane (TMGPS)) in anhydrous acetone. Solution 1H NMR spectroscopy was initially used to study the rate and extent of silane reactivity with AMO-Zn2MgAl-CO3 LDH. Powder XRD, TEM, N2 BET specific surface area and total pore volume measurements showed that the structure and morphology of silane-treated AMO-Zn2MgAl-CO3 LDHs remained largely unchanged. Solid state 13C CP-MAS, 27Al DP-MAS and 29Si CP-MAS NMR spectroscopy indicates that the silanes have been successfully grafted onto the surface of the LDH. In addition to maintaining their structure, morphology, high surface area and total pore volume, these surface-functionalised LDHs are now more hydrophobic, displaying a saturation water vapour uptake (<4 wt%) that is ca. 60% lower than the untreated AMO-LDH.

One-Step Transformation of Metal Meshes to Robust Superhydrophobic and Superoleophilic Meshes for Highly Efficient Oil Spill Cleanup and Oil/Water Separation.

Phytic acid (PA), which is a natural and innoxious plant constituent, can strongly adsorb on the metal surface because of its six phosphate groups. In this work, based on the chelating properties of PA and the reaction between PA and hydrolyzable vinyltriethoxysilane (VTES), we developed a novel and facial strategy to generate hierarchical-layer nanospheres on the metal mesh surface and fabricated robust superhydrophobic and superoleophilic miniature metal mesh ships. Because of their superwetting properties, the modified meshes could easily remove and recycle the oil spills from the water surface (>90% collection efficiency), and have high oil/water separation capacity (>96%). The excellent stability, corrosion resistance, and robust mechanical durability endow the modified mesh ships with more advantages in a marine environment. We envision that these superhydrophobic meshes modified with PA and VTES are sustainable, environmentally friendly, and easy to scale up and hence display great potential in practical application.

Formation of an in situ nanosilica nanomatrix via graft copolymerization of vinyltriethoxysilane onto natural rubber

Natural rubber (NR) with an in situ nanosilica nanomatrix was characterized in present work. The in situ nanosilica nanomatrix was prepared via graft copolymerization of a silane monomer, vinyltriethoxysilane (VTES), onto deproteinized NR (DPNR) in latex stage using tetrapentamine (TEPA)/tert‐butylhydroperoxide (TBHPO) as initiators. VTES conversion of more than 80% was obtained, and it depended on VTES concentration. The graft copolymer structure was characterized by Fourier transform infrared (FT‐IR), solution‐state proton nuclear magnetic resonance (1H‐NMR), and solid‐state 29Si‐NMR spectroscopy. FT‐IR analysis of the graft copolymer confirmed the formation of in situ silica particles, while solution‐state 1H‐NMR and solid‐state 29Si‐NMR revealed the partial hydrolysis of the ethoxy groups and polycondensation of the silanol groups. The formation of nanosilica particles enhanced thermal and mechanical properties of the graft copolymer. Morphology observations of the in situ nanosilica nanomatrix through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the spherical nanosilica particles form a nanomatrix surrounding NR particle. The formation of the nanomatrix was proved to enhance mechanical properties for NR materials.

Synthesis and characterization of multiple-crosslinkable polyacrylate emulsion for PVC film ink

Multiple-crosslinkable polyacrylate emulsion (MCPE) with high content of crosslinkable monomers was successfully synthesized via core-shell emulsion polymerization. Specially, cross-linkable monomers MAA and NMA were designed as the core layer monomers, vinyl triethoxysilane (A151) and epoxy resin (BC2060) were designed as the shell layer monomers, and aziridine (XR-100) was added as crosslinker. The hard core can be benefit for rapid drying of the film at room temperature, the soft shell can exhibit good film-forming ability. Epoxy resin was grafted on the chain of polyacrylate, which can endow excellent adhesion performance. The stability of MCPE was excellent and the core-shell structures of MCPE particles were maintained after stored for 15days at 50 °C, because those different crosslinkable monomers were introduced into different layers of the emulsion particles. The crosslinking density, tensile strength and glass transition temperature (Tg) of MCPE films were obviously higher than those of pure polyacrylate emulsion films due to the modification of several cross-linkable monomers. The MCPE ink film on PVC film has rapid surface drying performance, excellent adhesion and alcohol scrubbing resistance after multiple cross-linking at room temperature. All these advantages of this emulsion may contribute to its wide applications in the field of PVC film packaging and decoration.