Organofunctional Silanes Research Articles

Design of Carbon Dots Photoluminescence through Organo-Functional Silane Grafting for Solid-State Emitting Devices

Advanced optical applications of fluorescent carbon dots (C-dots) require highly integrated host-guest solid-state materials with a careful design of C-dots – matrix interface to control the optical response. We have developed a new synthesis based on the grafting of an organo-functional silane (3-glycidyloxypropyltrimethoxysilane, GPTMS) on amino-functionalized C-dots, which enables the fabrication of highly fluorescent organosilica-based hybrid organic-inorganic films through sol-gel process. The GPTMS grafting onto C-dots has been achieved via an epoxy–amine reaction under controlled conditions. Besides providing an efficient strategy to embed C-dots into a hybrid solid-state material, the modification of C-dots surface by GPTMS allows tuning their photoluminescence properties and gives rise to an additional, intense emission around 490 nm. Photoluminescence spectra reveal an interaction between C-dots surface and the polymeric chains which are locally formed by GPTMS polymerization. The present method is a step forward to the development of a surface modification technology aimed at controlling C-dots host-guest systems at the nanoscale.

Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization

Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85% relative humidity) exposure over 1000 h and then demonstrate how surface modification impacts changes in electrical and optical properties and chemical composition in one of the most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure but indicate a slight increase in surface roughness on both the nanometer and micrometer length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. This work demonstrates that surface modification slows the bulk degradation of AZO and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.

Effects of silane modified minerals on mechanical, microstructural, thermal, and rheological properties of wood plastic composites

Abstract This experimental study investigates the influence of silanized micro-size silicate-based minerals on mechanical, thermal, and rheological properties of wood (maple) polymer (high-density polyethylene) composites. The silicate-based minerals used in the experiments are prepared from mine tailings through the inertization process (acid leaching). Two different types of organo-functional silanes including vinyl-trimethoxy and amino-ethyl amino-propyl trimethoxy silanes (3%) are used to modify the mineral fillers. The different amounts of mineral fillers (1–5%) are added to the composites as wood filler replacement and while the composite properties are evaluated. The obtained results implicated that the addition of 1% silane modified minerals decreases the rigidity and increases the ductility (up to 25%) of wood polymer composite. Mineral fillers modified with vinyl-silane were more effective to improve both tensile and flexural strengths and less advantageous on rheological behaviour. Amine-modified minerals had no negative influence on rheological performance even if they significantly decreased the rigidity of composites. Both surface modified minerals improved the thermal stability of wood plastic composites.

Organosilane modified Zr-based conversion layer on Zn–Al alloy coated steel sheets

Abstract Conversion layers based on amorphous Zirconium oxide are still in focus to replace state-of-the-art pre-treatment technologies like chromate- and phosphate-based inorganic protection coatings in different industrial sectors. Besides exceeding corrosion protection properties these layers offer sufficient adhesion behaviours. To investigate the influence of organofunctional silanes on the protection properties of these pre-treatment systems, 3-gylcidoxypropyltrimethoxysilane (γ-GPS) was added to the aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H 2 ZrF 6 ). The surface composition of these modified conversion layers was determined using X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (FT-IRRAS) and confocal Raman microscopy (CRM). Scanning Kelvin Probe (SKP) measurements were obtained on organic coated samples in order to investigate the corrosive cathodic delamination process in more detail.

Silanized graphene oxide reinforced organofunctional silane composite coatings for corrosion protection

Abstract Silanized graphene oxide (SGO) reinforced organofunctional silane composite coatings were fabricated on galvanized steel substrates. A mixture of silane precursors were employed to prepare the composite matrix. The graphene oxide surfaces were functionalized by tetraethoxysilane molecules to improve its compatibility with the silane matrix. The protective properties of the composite coatings were significantly improved compared with the neat silane coatings. The composite coatings exhibited the highest protective properties with the addition of 0.2 wt% of SGO. Silanized graphene provided a physical barrier to the corrosive molecules.

The "Clickable" Method for Oligonucleotide Immobilization Onto Azide-Functionalized Microarrays.

The DNA microarray technique was supposed to help identifying and analyzing the expression level of tens of thousands of genes in the whole genome. But there is a serious problem concerning fabrication of the microarrays by chemical synthesis, such as specific and efficient linking of probes to a solid support. Therefore, we reckon that applying "click" chemistry to covalently anchor oligonucleotides on chemically modified supports may help construct microarrays in applications such as gene identification. Silanization of the glass support with organofunctional silane makes it possible to link azide groups on glass surface and the nucleic acid probe that is equipped with a pentynyl group. This is followed by direct spotting of the nucleic acid on the azide-modified glass support in the presence of copper ions, and this is a frequently applied method of "click" chemistry.

Organofunctional Silane Inhibitor Surface Treatment of Concrete for Corrosion

With increased attention to service life, bridge decks are now being designed to perform for 75 to more than 100 years without major repairs. In areas where deicing salts are used, sustainable and cost-effective solutions utilize concretes with a water-to-cementitious material ratio (w/cm) less than 0.40, concrete cover over the reinforcement greater than or equal to 2 in., and additional corrosion protection measures, such as corrosion-resistant reinforcement or corrosion inhibitors. Concretes with a w/cm less than 0.40 require higher cement contents and can be more susceptible to cracking, even with the use of supplementary cementitious materials. This paper discusses 3 years of accelerated corrosion test data on an alternative solution that could utilize more moderate cementitious levels but still reduce chloride ingress and potentially raise chloride threshold levels for corrosion initiation by applying a low surface tension organofunctional silane inhibitor to the surface before exposure to chloride.

Improvement of adhesion strength of self-adhesive silicone rubber on thermoplastic substrates – Comparison of an atmospheric pressure plasma jet (APPJ) and a Pyrosil® flame

Polymeric hard/soft combinations consisting of a rigid, thermoplastic substrate and an elastomeric component offer many advantages for plastic parts in industry. Manufactured in one step by multi-component injection moulding, the strength of the thermoplastics can be combined with sealing, damping or haptic properties of an elastomer. Bonds of self-adhesive liquid silicone rubber (LSR) on high performance thermoplastics such as polyetheretherketone (PEEK) or polyphenylene sulphide (PPS) are especially interesting e.g. for medical applications due to their outstanding resistance properties. To ensure good adhesion between the two components, surface treatments from an atmospheric pressure plasma jet (APPJ) and a Pyrosil® flame are applied. Chemical changes on the thermoplastic surfaces are verified by water contact angle measurement (CA) and X-ray photoelectron spectroscopy (XPS). Plasma treatment causes a decline in water contact angle, indicating the formation of functional groups, especially –OH, on the surface. XPS measurements confirm the increase of oxygen on the surface. Thus, the number of functional groups on the thermoplastic surface is enlarged by plasma treatment, leading to stronger bonding to the organofunctional silanes of the self-adhesive silicone rubber. A thin layer of silanol groups is created by the Pyrosil® flame on the thermoplastic substrates, which could be verified by XPS. A hydrophilic behaviour of the coated surface is noticed. Both surface modification methods lead to enhanced adhesion properties of self-adhesive LSR on thermoplastic surfaces. This is confirmed by 90°- peel tests of the injection-moulded composites leading to an increase in peel force by the applied surface modification techniques.

Degradation of transparent conductive oxides: Interfacial engineering and mechanistic insights

Transparent conductive oxides (TCOs) are a known failure mode in a variety of thin film photovoltaic (PV) devices, through mechanisms such as resistivity increase and delamination. Degradation science studies of these materials, as well as most PV systems, have primarily utilized industry standard qualification protocols, which are not designed to be used as lifetime prediction tests. This work applies a data science approach to this engineering challenge, utilizing commercially available TCOs and subjecting them to an array of stressors, including environmental and material stressors. Optical, electrical and surface sensitive TCO property metrics were monitored and analyzed en mass. Different degradation mechanisms and modes were observed when different stressor combinations were applied; TCO surfaces are sensitive to the proportion of water and light in an exposure, yellowing of the TCO only occurs when humidity and UV light are combined, and PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) application results in hazing and roughening of aluminum-doped zinc oxide (AZO). Using multi-variate analytics and plotting critical material properties against one another in a mechanistic plot, trade-offs between properties and the activation of different degradation mechanisms become readily apparent. In addition to a survey of failure modes of TCOs, a possible solution to the degradation of AZO was examined: the application of an organofunctional silane layer. The application of a thin APTES (3-aminopropyltriethoxysilane) film nearly eliminated the observed edge effects and greatly reduced the resistivity increase caused by damp heat exposure of AZO.

Stable carboxylic acid derivatized alkoxy silanes.

A convenient and straightforward one-pot hydrosilylation reaction of different unsaturated carboxylic acids with trialkoxysilanes in the presence of catalytic amounts of platinum(IV) dioxide resulted in excellent yields in organofunctional silanes combining carboxy- and alkoxy groups within one molecule.

Biofunctional hybrid materials: bimolecular organosilane monolayers on FeCr alloys

Hybrid organic–inorganic interfaces are the key to functionalization of stainless steel (SS). We present a solution-based deposition method for fabricating uniform bimolecular organosilane monolayers on SS and show that their properties and functionalities can be further developed through site-specific biotinylation. We correlate molecular properties of the interface with its reactivity via surface sensitive synchrotron radiation mediated high-resolution photoelectron spectroscopy (HR-PES) and chemical derivatization (CD), and we demonstrate specific bonding of streptavidin proteins to the hybrid interface. The method facilitates efficient growth of uniform bimolecular organosilane monolayers on SS under ambient conditions without the need to prime the SS surface with vacuum-deposited inorganic buffer layers. The obtained insights into molecular bonding, orientation, and behaviour of surface-confined organofunctional silanes on SS enable a new generic approach to functionalization of SS surfaces with versatile nanomolecular organosilane layers.

Controlling the synergetic effects in (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane coadsorption on stainless steel surfaces

A versatile and economic method of preparing covalently-bound and uniform bifunctional silane monolayers on stainless steel is presented. Stainless steel is first electrochemically hydroxylated to enable the formation of a bifunctional overlayer via simultaneous liquid-phase deposition of two organofunctional silanes: (3-aminopropyl)trimethoxysilane (APS) and (3-mercaptopropyl)trimethoxysilane (MPS). The chemical composition, in-depth distribution, molecular orientation and chemical bonds in APS, MPS and APS/MPS layers over a range of APS/MPS mixing ratios are studied with synchrotron radiation mediated photoelectron spectroscopy (SR-PES), conventional X-ray photoelectron spectroscopy (XPS) and energy filtered X-ray photoemission electron microscopy (EF-XPEEM). Inelastic electron energy-loss background (IEEB) analysis is employed to determine the surface morphology of the silanized samples. Coadsorption is shown to produce a covalently-bound and highly ordered monolayer with a controllable MPS surface concentration within APS matrix. The results show evidence of strong synergistic effects during simultaneous adsorption of MPS and APS from liquid phase. While the uptake of MPS alone is low, the coadsorption of MPS and APS strongly enhances both the uptake of MPS and ordering in the APS/MPS overlayer. Results from PES, EF-XPEEM and IEEB analysis reveal that the surface is predominantly covered by a well-ordered APS/MPS monolayer with only slight degree of clustering. Clustering is attributed to different hydrolysis rates in solution and structural irregularities on the substrate. Our results conclusively invalidate the assumption that APS/MPS ratio in a deposited overlayer should correlate linearly with the mixing ratio in solution. The reported insights into the chemical bonds, molecular orientation and morphology in APS/MPS overlayers facilitate site-selective coupling of functional molecules to amino and thiol groups with controllable spatial distribution and, in general, knowledge-based development of novel surface functionalities for stainless steel and other metal (alloy) oxides.

Mixed bifunctional surface-modified silicas using tethered aminofunctional silane catalysts

Amines are known to catalyse silica surface reactions with alkoxy functional organosilanes. In this work, a substoichiometric amount of an aminofunctional silane is bound to the silica surface by reaction with available silanols. This surface bound amine is used to catalyse the reaction of nearby silanols in its vicinity. The result is a bifunctional modified silica surface with two different functional groups intimately mixed at the molecular level. Three types of silicas were modified with a substoichiometric amount of different aminofunctional silanes possessing various structures. These amino-modified silica surfaces were then exposed to a relatively unreactive alkylsilane that requires the presence of an amine for catalysis of the surface reaction. Select materials were characterized by FTIR, TGA, as well as 29Si and 13C solid state NMR. Elemental analysis data was obtained for all materials after aminosilane reactions and after alkylsilane reaction, with and without the presence of surface bound aminosilane present, for quantitative analysis. Each surface bound aminosilane catalyses the reaction of approximately one alkylsilane. An aminosilane that is bound with one bond to the surface catalyses a greater number of alklylsilanes per aminosilane. Surface modified aminosilanes on nanoparticulate fumed silica on average catalyse a greater number of alkylsilanes compared to silica gels. This is the first report demonstrating the feasibility of using a surface bound aminosilane as a catalyst to synthesize intimately mixed bifunctional silica surfaces.

Flexible epoxy‐silicone rubber laminates for high voltage insulations with enhanced delamination resistance

In this work, functionalized damping layers consisting of crosslinked silicone rubber are incorporated into brittle epoxy‐based composites to improve the delamination resistance of high voltage insulations. Selected functional organosilanes are attached onto the elastomer surface by a two‐step modification to ensure a covalent bonding between the thermosetting resin and the damping layer. Functional model insulations and stator bar prototypes are then prepared with a vacuum pressure impregnation process. The influence of the damping layer on the thermo‐mechanical and electrical properties as well as the delamination resistance is characterized. The results give evidence that the flexibility of the new composite materials can be increased significantly whereas the electrical properties are not affected by the elastomer layer. By evaluating the performance of the stator bar prototypes it can be clearly shown that both delamination resistance as well as high voltage endurance can be enhanced considerably by the application of flexible damping layers. POLYM. COMPOS., 36:2238–2247, 2015. © 2014 Society of Plastics Engineers

Thermal conductivity of filled sol‐gel‐derived hybrid materials

ABSTRACTA novel sol‐gel‐based hybrid material has been synthesized from organofunctional silanes and aluminates via hydrolysis and condensation reactions. The hybrid material was—in comparison to a silicone rubber—filled with equal amounts of metal filler particles in order to investigate the effective thermal conductivity. The data obtained were compared with theoretical models available in literature to gain understanding of mechanisms responsible for the measured conductivities. Samples were prepared via casting and spin‐coating techniques on Teflon® and silicon substrates and characterized using laser flash analysis (LFA) and scanning electron microscopy (SEM). It was demonstrated, that the hybrid material with an aluminum content of 40 vol % offers the possibility to achieve an up to five times higher thermal conductivity than filled silicone references. The influence of thermal transition between matrix material and filler was evaluated by a sandwich‐layer setup. The results suggest that increased thermal conductivity is also caused by the lower thermal resistance and improved interphase connections within the hybrid material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41037.

Properties of Polypropylene and Surface Modified Glass-Fibre Composites

To improve the interfacial bonding between polypropylene (PP) and glass-fibre (GF), the surface modified glass-fibre (SMGF) was prepared with the self-designed sizing containing organofunctional silanes and a copolymer. Then the SMGF-PP composites were prepared and those properties were observed by mechanical testing, light microscopy, X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical tests displayed that SMGF-PP composites had an increase in tensile strength, tensile modulus, bending strength, bending modulus and notched impact strength compared to the pure PP. Light micrographs showed that the average fibre length of the composite was 397 μm. XRD data indicated that the crystal size of SMGF-PP composites became smaller compared to pure PP, and β form crystals of PP disappeared with the addition of SMGF to PP matrix. DSC data showed that SMGF could promote the crystallization temperature of PP. TGA analyses showed that the thermal stability of SMGF-PP was better than that of pure PP.

Coupling pattern and efficacy of organofunctional silanes in wood flour-filled polypropylene or polyethylene composites

The coupling efficacies of four silanes, i.e. n-propyl-trimethoxysilane, γ-amino-propyltrimethoxysilane, γ-methacryloxypropyl trimethoxy silane, and allyltrimethoxysilane, were investigated in wood flour-filled polypropylene or polyethylene composites. Compared to untreated composites, treatment of wood flour with these silanes alone did not cause any improvement in the mechanical strength of the ensuing composites. In the presence of dicumyl peroxide, composites treated with γ-methacryloxypropyl trimethoxy silane and allyltrimethoxysilane exhibited an increase up to 90, 60, and 50% in flexural, tensile, and impact strength, respectively. Moreover, creep deformation was inhibited during the creep recovery test. The improvement was obviously greater in polyethylene-based composites than in polypropylene-based composites. This study demonstrates that the coupling efficacy of silane depends not only on the establishment of covalent bonds between silane and the matrix, but also on the chemical structure of the matrix.

Chemical modification of nanometric TiO2 particles by anchoring functional silane molecules in supercritical CO2

Supercritical carbon dioxide (scCO2) was used as a green solvent for the grafting of complex functional organosilanes containing nitrogen moieties on titanium dioxide (TiO2) nanoparticles using two strategies. The first strategy involved the preparation of two functional silanes, 4-nitrophenyl-(3-(trimethoxysilyl)-propyl)methanimine (NPTMS) and 4-(((3-(trimethoxysilyl)propyl)imino)methyl)-benzaldehyde (FPTMS) and further deposited under anhydrous conditions and scCO2 onto the TiO2 surface. The second strategy involved the scCO2 anhydrous deposition of bifunctional commercial silanes on the TiO2 surface. Two structures were synthesized. The first consisted in grafted TiO2 nanoparticles prepared by addition of the ligand, ((1R,2R)-N-(pyridin-2-ylmethyl)-2-(((E)-pyridin-2-ylmethylene) amino)-cyclohexan-1-amine (LPy-red), and designated as Ti-Cl-LPy-red. The second structure was synthesized by the reaction of (1,2)-diaminocylohexane (Dac), through the reactive site of 3-(Trimethoxysilyl)propyl methacrylate (MPTMS) previously deposited on the TiO2 surface and designated as Ti-MP-Dac. The synthesized silanes were characterized by ATR-FT and NMR spectroscopies and mass spectrometry. ATR-FT spectroscopy confirmed the presence of the silanes on the surface of the hybrid nanoparticles. Thermogravimetic analysis was used to estimate the loading of the silane grafted through both hydrogen and covalent bonding on the TiO2 surface. Further characterization of the solid samples was done by N2 adsorption–desorption and UV–vis diffuse reflectance.

Research paper Application of epoxy functional silanes in the preparation of DNA microarrays

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Frydrych-Tomczak E, Uszczyńska B, Ratajczak T, et al. Application of epoxy functional silanes in the preparation of DNA microarrays. BioTechnologia. 2014;95(1):5-16. doi:10.5114/bta.2014.46408. APA Frydrych-Tomczak, E., Uszczyńska, B., Ratajczak, T., Markiewicz, W., Figlerowicz, M., & Nowicki, M. et al. (2014). Application of epoxy functional silanes in the preparation of DNA microarrays. BioTechnologia, 95(1), 5-16. https://doi.org/10.5114/bta.2014.46408 Chicago Frydrych-Tomczak, Emilia, Barbara Uszczyńska, Tomasz Ratajczak, Wojciech T. Markiewicz, Marek Figlerowicz, Marek Nowicki, and Hieronim Maciejewski et al. 2014. "Application of epoxy functional silanes in the preparation of DNA microarrays". BioTechnologia 95 (1): 5-16. doi:10.5114/bta.2014.46408. Harvard Frydrych-Tomczak, E., Uszczyńska, B., Ratajczak, T., Markiewicz, W., Figlerowicz, M., Nowicki, M., Maciejewski, H., and Chmielewski, M. (2014). Application of epoxy functional silanes in the preparation of DNA microarrays. BioTechnologia, 95(1), pp.5-16. https://doi.org/10.5114/bta.2014.46408 MLA Frydrych-Tomczak, Emilia et al. "Application of epoxy functional silanes in the preparation of DNA microarrays." BioTechnologia, vol. 95, no. 1, 2014, pp. 5-16. doi:10.5114/bta.2014.46408. Vancouver Frydrych-Tomczak E, Uszczyńska B, Ratajczak T, Markiewicz W, Figlerowicz M, Nowicki M et al. Application of epoxy functional silanes in the preparation of DNA microarrays. BioTechnologia. 2014;95(1):5-16. doi:10.5114/bta.2014.46408.

Properties of oxide-silane composite coating on AZ31 magnesium alloy

Various oxide films have been grown on AZ31 magnesium alloy by microarc oxidation in alkaline phosphate solution with addition of different compounds (Na2SiO3, NaAlO2). Because of the anodic oxide porosity, arising from the sparking treatment, organo-functional silane coatings have been applied to seal pores and cracks and achieve a more effective protective system. The surface and cross-section morphologies of the anodic films were analysed by scanning electron microscopy. The phase composition was determined by X-ray diffraction. Bare and anodised AZ31 specimens were post-treated with silanes, namely N-phenil-3-aminopropyltrimethoxysilane and Bis (trimethoxysilylethyl) benzene. The corrosion resistance of anodic oxides and oxide-silane composite coatings was evaluated in dilute Harrison solution by means of single-cycle anodic polarisation. The results showed that the addition of different salts to the alkaline phosphate solution affects the surface morphology and the phase composition of the coatings and, as a consequence, the corrosion resistance behaviour. Both silane post-treatments provide further corrosion protection to samples anodised in aluminate containing solution.