The preparation and characterization of pyroelectric hybrid films containing C.I. Acid Red 29 (chromotrope 2R)

Pyroelectric hybrid materials were prepared from 4,5-dihydroxy-3-(phenyldiazenyl)naphthalene-2,7-disulfonic acid (C.I. Acid Red 29) and Nb or Ta alkoxides via a sol–gel process. The hybrid materials were analyzed and characterized using infrared spectrometry, atom force microscopy and thermal gravimetry differential thermal analysis. The dye was covalently linked to the inorganic network and organic–inorganic hybrid films had excellent pyroelectric character (average pyroelectric coefficient 1.79 × 10⁻⁶ C cm⁻² K⁻¹) and high thermal stability; no phase separation was observed in the films.     

Mesoporous hybrid zirconium oxophenylphosphate synthesized in absence of any structure directing agent

A new organic–inorganic hybrid mesoporous zirconium oxophenylphosphate (ZPP-1) has been synthesized hydrothermally at 443 K by using phenylphosphonic acid (PPA) as phosphorus source in absence of any structure directing agent. Powder XRD, TEM, FE SEM, N₂ sorption, CHN and ICP-AES chemical analyses, ¹³C CP/MAS and ³¹P MAS NMR, UV–visible and FT IR spectroscopic tools and thermal analysis were employed to characterize this novel material. XRD, N₂ sorption and TEM image analysis suggested the existence of multi-lamellar structure of the pore wall with large micropores and mesopores having peak maximums of ca. 1.5 and 5.0–6.0 nm, respectively in this ZPP-1 material. Interestingly, this hybrid material showed very high thermal stability together with retention of nanostructure and phenyl group when heated upto 723 K. ZPP-1 showed fairly high H₂ adsorption capacity under atmospheric pressure at 77 K. Possible templating role played by the framework phenyl groups has been discussed.     

Synthesis and characterization of urea bridged hybrid periodic mesoporous organosilica materials

Urea bridged organic–inorganic hybrid mesoporous SiO₂ materials (U-BSQMs) were synthesized through a sol–gel procedure by co-condensation of bis(triethoxysilyl propyl) urea (BSPU) under basic conditions using cetyltrimethylammonium bromide (CTAB) as organic template. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the mesoporous structure of the sample. Fourier-transform infrared spectroscopy (FT-IR), solid state CP-MAS NMR spectroscopy of ²⁹Si (²⁹Si CP-MAS NMR) and ¹³C (¹³C CP NMR) indicated that most of the Si–C bonds are unbroken during the synthesis process. The N₂ adsorption–desorption results revealed that these hybrid mesoporous SiO₂ materials have bimodal distribution of pores with pore diameters of 2.4 and 3.8 nm, respectively. Thermogravimetric analysis (TG) demonstrated that about 16% Si–C bonds have been broke during the synthesis progress. This kind of material is expected to find possible application in ion supporting, drug delivery and catalysis.     

Synthesis of fluorinated/methacrylated epoxy based oligomers and investigation of its performance in the UV curable hybrid coatings

Organic–inorganic hybrid coatings based on fluorinated/methacrylated soybean oil and bisphenol A/F epoxy methacrylate were obtained by combining photopolymerization and sol–gel process. Hard and transparent hybrid coatings were prepared on polycarbonate panels and their physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in fluorine and sol–gel precursor contents. Thermo gravimetric analysis results demonstrated that fluorine and silica incorporations significantly enhanced the thermal oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.     

Preparation of epoxy-silica-acrylate hybrid coatings

Summary An organic-inorganic epoxy-silica-acrylate hybrid coating had been prepared by radical solution copolymerization and sol-gel process. The room curing reaction of the hybrid coating was discussed, and its structure, optical properties and thermal stability were studied. The hybrid coatings have multiple functional groups, and the inorganic phase and organic phase are linked by the chemical bonding. When tetraethylorthosilicate (TEOS) mass fraction were 10% and 20%, hybrid coatings had inorganic particle mean sizes of 36 nm and 45 nm, respectively, together with their homogeneously distribution within the polymeric matrix. With increasing of TEOS content, the transmittance in the visible region and the yellow index (YI) of the hybrid coatings after UV irradiation decrease, while the absorbency at 300–400 nm, the onset decomposition temperature and maximum weight loss temperature increase.     

Sensitive glasslike sol–gel materials suitable for environmental light sensors

New sol–gel based sensitive materials able to detect moderate doses of UV, Vis and near IR radiations have been designed, prepared and characterised. These glasslike detectors are respectively composed by four different sols of inorganic and hybrid organic–inorganic silica matrixes. The sols were prepared from alkoxide (TEOS) and alkylalkoxide (GLYMO) precursors with molar ratios 1:0, 1:1, 1:4 and 0:1, respectively. All the sols were doped with an organic photochromic dye (spiropyran). The detectors characterisation was carried out by means of exposures to natural light under different light intensities (100–3000 lx). The highest sensitivity against the light radiation was found for sols with molar ratio TEOS:GLYMO of 1:1. The time response of detectors is found at about 10 min and their life time is roughly 4 months at least. Moreover, the detectors show good optical reversibility. These sensitive glasslike materials have been designed to be applied for preservation of historical goods. They can detect and evaluate dangerous light doses for the proper conservation conditions of historical materials, which are sensitive or moderately sensitive against light radiation (<600 lx).     

Solid electrolyte based on silicate matrix functionalised with tetraalkylammonium group solvated by organic solvent

Solid electrolyte composed of hybrid organic–inorganic silicate matrix functionalised with tetraalkylammonium group, solvated by viscous organic polar solvent (propylene carbonate (PC) or sulpholane (TMS)), was prepared by the sol–gel method under controlled drying conditions. Tetramethoxysilane (TMOS), N-trimethoxysilylpropyl-N,N,N-tributylammonium chloride (TMOSPTBACl) and organic solvent were principal sol components. Gel formed within 2 h and 2 days depending on substrate ratio and the solvent additive. The obtained material was transparent and it loosed about 15% of its mass during first 30 days of ageing. It was characterised by thermogravimetry (TGA), differential scanning calorimetry (DSC), NMR, FT-IR spectroscopy, small angle X-ray scattering (SAXS), and impedance spectroscopy. The transport of redox active molecules was studied by electrochemical methods. The porosity of samples dried in supercritical CO₂ was also estimated. The shape of TGA and DSC curve appeared to be similar to that of pure solvent. The IR spectra indicated the silicate network formation with some silanol groups left. The NMR spectrum of the solution used to wash crushed sample indicated that all organic substrate is embedded in silicate matrix. The magnitude of electrical conductivity was close to 10⁻⁴ to 10⁻⁵ S cm⁻¹, i.e. least more than one order of magnitude larger than that of TMOS based silicate matrix modified with a pure solvent. This conductivity is high enough for electrochemical experiments. Both conductivity and diffusion coefficient of redox probe-ferrocene (Fc) depended on time elapsed after gelation. Their most substantial decrease was observed during first 10 days after gelation and it correlated with mass loss.     

Preparation and characterization of UV‐curable organic/inorganic hybrid composites for NIR cutoff and antistatic coatings

In this study, UV‐curable organic/inorganic hybrid composite coatings with near infrared (NIR) cutoff and antistatic properties were prepared by high‐shear mixing of two kinds of polymer matrices and coated on plastic and glass substrates by the doctor‐blade method. This study also investigated the morphology, stability, optical properties, electrical resistivity, and durability of the UV‐cured composite coats. It was found that the composite coatings were very stable under centrifugation. Moreover, the films with transmittance of above 80% in a visible light region (400–800 nm) and of ～ 40% to 50% in the NIR region (1000–1600 nm) showed low haze of 6.9%, electrical resistivity of around 2.3 × 10⁷ Ω/square. Thus, excellent adhesion, scratch, and weathering durability can be produced on polycarbonate substrate at room temperature. The experimental results reveal that UV‐curable organic/inorganic hybrid composites can be used effectively to fabricate films with NIR cutoff as well as antistatic properties, indicating a high potential for practical application in architectural, automotives, and optoelectronics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Silica based organic–inorganic hybrid nanocomposite coatings for corrosion protection

Silica based organic–inorganic hybrid nanocomposite coatings have been developed for corrosion protection of 1050 aluminum alloys by dip coatings technique. The hybrid sols were prepared by hydrolysis and condensation of 3-glycidoxypropyl-trimethoxysilane (GPTMS) and tetramethoxy silane (TMOS) in the presence of an acidic catalyst and bisphenol A (BPA) as cross-linking agent. Such prepared hybrid coatings were found to be relatively dense, uniform and defect free. Structural characterization of the hybrid coatings were performed using optical microscopy, scanning electron microscopy (SEM) and attenuated total reflectance-infrared (ATR-IR) spectroscopy. Corrosion resistance properties of the hybrid sol–gel coatings were studied by potentiodynamic scanning (PDS) and salt spray testing methods. The results indicate excellent barrier protection performance of the coatings. In addition, the effect of molar ratio of GPTMS–BPA (silane content) on corrosion resistance of the coatings was investigated. The PDS results demonstrated that the corrosion resistance of hybrid coatings improved by decreasing of silane content.     

Synthesis and characterization of abrasion resistant coating materials prepared by the sol-gel approach: I. Coatings based on functionalized aliphatic diols and diethylenetriamine

The synthesis of inorganic organic hybrid materials has been undertaken and used as abrasion resistant coatings for polymeric substrates by the sol-gel method. The organic components are diethylenetriamine (DETA), glycerol, and a series of aliphatic diols which are functionalized by 3-isocyanatopropyltriethoxysilane. The inorganic components are tetramethoxysilane (TMOS), aluminum tri-see-butoxide, titaniumsec-butoxide and zirconiumn-propoxide. Solutions of these materials are spin coated onto bisphenol-A polycarbonate sheet and thermally cured to obtain a transparent coating of a few microns in thickness. Following the curing, the abrasion resistance is measured and compared with a control having no coating. It was found that the abrasion resistance of inorganic organic hybrid coatings in the neat form or containing additional silicon, titanium, zirconium, and aluminum alkoxides can be very effective to improve abrasion resistance. The adhesion tests show that the adhesion between coating and substrate can be greatly improved by treating the polymeric substrate surface with an oxygen plasma or a primer solution of isopropanol containing 3-aminopropyltriethoxysilane. Other experiments, such as the abrasion resistance tests following conditioning in a hot-wet condition (boiling water treatment), microhardness tests. UV absorption behavior, and the observation of abraded surfaces, were also undertaken in order to evaluate these coating materials.     

Scratch resistance and oxygen barrier properties of acrylate-based hybrid coatings on polycarbonate substrate

Organic/inorganic hybrid coating materials were synthesized using acrylate end-capped polyester, 1,6-hexanediolacrylate, tetraethoxysilane (TEOS), and 3-trimethoxysilylpropylmethacrylate (TMSPM). The hybrid materials were cast onto a polycarbonate (PC) substrate and cured by UV irradiation to give a hybrid film with covalent linkage between the inorganic and the organic networks. The coating layer was characterized by FT-IR and ²⁹Si-NMR, and pencil hardness and oxygen permeation rate of coated films were investigated. The pencil hardness of all samples examined in this study was higher than 1H, whereas that of uncoated PC substrate was 6B. The hardness enhancement after coating may due to incorporation of organic acrylate resin. The oxygen permeability coefficient of the film coated with hybrid material on 3-aminopropyltriethoxysilane (APTEOS) pretreated polycarbonate substrate was 1.67×10⁻³ GPU, the lowest value in this work, whereas that of uncoated PC substrate was 8.07×10⁻³ GPU. The lower oxygen permeation rates of these films are attributed to the good adhesion between organic/inorganic hybrid coating layer and PC substrate and a dense structure induced by an increase of network density.     

Preparation and characterization of UV‐cured hybrid coatings by triethoxysilane‐modified dimethacrylate based on bisphenol‐s epoxy

Novel hybrid oligomers based on a UV‐curable bisphenol‐S epoxy dimethacrylate (DBSMA) were synthetized. DBSMA was modified with various amount of (3‐isocyanatopropyl)triethoxysilane coupling agent. The modification degree of the hybrid oligomer was varied from 0 to70 wt %. The photopolymerization kinetics was monitored by a real‐time infrared spectroscopy. The conversion and rate of hybrid coatings increased with the increase in modification degree. UV‐curable, hard, and transparent organic–inorganic hybrid coatings were prepared. They were performed by the analyses of various properties such as surface and mechanical properties. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in modification degree. The thermal behavior of coatings was also investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Indenyl-silica xerogels: new materials for supporting metallocene catalysts

Inorganic–organic hybrid xerogels bearing indenyl groups on their surfaces have been synthesised by the sol–gel method. The hybrid xerogels were obtained by hydrolysis and polycondensation of bisindenyldiethoxysilane (Ind₂Si(OEt)₂) and tetraethoxysilane, TEOS (Si(OEt)₄) under two different conditions. Chemical structure was investigated by ultraviolet spectroscopy (UV–VIS), transmittance (FT-IR) and diffuse-reflectance (DRIFTS) infrared spectroscopy, magic angle spin nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopy (XPS). Xerogel texture and structure were analysed by nitrogen sorption based on the Brunauer–Emmett–Teller (BET) method, X-ray diffraction spectroscopy (XRD), and natural scanning electron microscopy (N-SEM). Under our experimental conditions, in alkaline milieu and 1:3 indenyl/TEOS ratio, a xerogel with higher indenyl content, but nonporous and showing agglomerate patterns was produced (xerogel I). Spherical particles of diameter about 6–8 μm where obtained in the absence of catalyst, using 1:5 indenyl/TEOS ratio, higher temperature and shorter reaction time (xerogel II). Xerogel II was used as support for heterogeneous metallocene catalyst synthesis. The resulting catalyst presented high Zr content (0.68 mmol Zr g_cat⁻¹) and high catalyst activity (40×10³ kg PE mol⁻¹ Zr h⁻¹) in ethylene polymerisation.     

Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings

UV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006     

A view from inside onto the surface of self-assembled nanocomposite coatings

Hybrid organic–inorganic (O–I) nanocomposite coatings with an O–I matrix and inorganic nanofillers were synthesized by two consecutive and independent processes: sol–gel process (build-up of inorganic structures with epoxide-functions in situ) and polyaddition reaction (epoxy network formation with amines). Two O–I matrices were prepared: the GTMS–D400 type exhibits a high degree of regularity and self-ordering in the bulk (inorganic domains separated by elastic D400 chains) while in the GMDES–T403 type a linear inorganic polyepoxide is homogeneously mixed with the amino component without any separated inorganic domains. Inorganic nanofillers (natural or chemically modified montmorillonites and colloidal silica) differing in size and shape, were added to the matrices. Core properties of the composite products, on sub-micrometer and micrometer levels were studied by solid-state NMR spectroscopy, transmission electron microscopy, and wide-angle X-ray scattering. Macroscopic, bulk properties of the materials were investigated by static and dynamic mechanical analysis. The gas transport properties of the prepared coatings were tested with hydrogen and oxygen. The surface morphology of the coatings with and without nanofillers was determined by atomic force and scanning electron microscopy. A high degree of self-organization existing already in the O–I matrix was observed in some cases, which obviously influences the self-assembly behaviour of the nanofillers in the O–I matrix and on the surface of the hybrid coatings.     

Bioactive and degradable organic–inorganic hybrids

CaO–SiO₂–poly(vinyl alcohol) (PVAL) and CaO–P₂O₅–SiO₂–PVAL organic–inorganic hybrids were obtained as monoliths and characterized before and after be soaked in a solution mimicking human plasma. The hybrids were obtained by adding PVAL (0.9, 1.8 and 3.6 wt.%) to three CaO–(P₂O₅)–SiO₂ gel glasses with 25 mol% of CaO and 0, 2.5 and 5 mol%, respectively of P₂O₅. The influence of PVAL and P₂O₅ on the monoliths obtaining and on their textural properties and in vitro behavior was analyzed. Additions of PVAL favored the synthesis of cracked-free monoliths able to be coated with bone-like apatite after be soaked in Kokubo's simulated body fluid (SBF), i.e. to present in vitro bioactivity. Increasing P₂O₅ contents made the hybrids syntheses difficult and decreased their in vitro bioactivity. In addition, the in vitro degradation of hybrids increased with the increasing of PVAL and P₂O₅. Thus, hybrids with the highest amounts of both components showed so high degradation in SBF that the apatite layer formation was impeded. Organic–inorganic hybrids in these systems could be clinically used as bone defect fillers in non load bearing applications or as matrices in controlled release systems.     

Synthesis and properties of an alkoxysilane dye containing three electronic donor groups for nonlinear optical applications

In order to obtain an efficient hybrid inorganic–organic nonlinear optical (NLO) materials, an azo-dye containing three electronic donor groups 2,5-dimethyl-4-(4′-nitrophenylazo)phenol (DMNPAP) was synthesized and reacted with 3-isocyanatopropyl triethoxysilane (ICTES) to give an alkoxysilane dye (ICTES–DMNPAP). Molecular structural characterizations for DMNPAP and ICTES–DMNPAP were investigated by elemental analysis, ¹H NMR, FTIR, UV–visible spectra and differential scanning calorimetry (DSC). The alkoxysilane dye could be hydrolyzed and polymerized in the presence of water, and then transparent hybrid films could be fabricated by spin coating on the indium–tin-oxide (ITO) glass substrates. Compared with the dye 4-nitro-4′-hydroxy-azobenzene (NHA) containing only one hydroxyl as donor group, DMNPAP exhibited larger β_CTμ_g value measured by solvatochromic method, and second harmonic generation (SHG) measurement of the hybrid films was in agreement with the result.     

Photocatalytic degradation of organic pollutants catalyzed by layered iron(II) bipyridine complex–clay hybrid under visible irradiation

An organic–inorganic layered hybrid was prepared by intercalation of Fe(bpy)₃²⁺ into laponite clay. UV–vis diffuse reflectance, X-Ray diffraction, and SEM confirmed the intercalation and the strong host–guest interaction of Fe(bpy)₃²⁺ molecules with the clay matrix. Compared with laponite, the hybrid formed a solid layered structure due to the linking of laponite platelets by Fe(bpy)₃²⁺ molecules. Upon visible light irradiation (λ > 420 nm), the hybrid was found to be highly effective for the degradation of nonbiodegradable cationic organic pollutants such as Rhodamine B (RhB) and N,N-dimethylaniline by activating H₂O₂ at neutral pH values, but inactive toward anionic organic compounds such as Orange II and Sulforhodamine-B. The adsorption and degradation of organics on the hybrid could be controlled by changing the pH value of the suspension. The total organic carbon (TOC) removal yield of RhB was 41%. pH effect trials and the final degraded products further indicate that unless the target is adsorbed onto the clay layers the reaction could not occur. Neither OH nor OOH/O₂⁻ EPR signals were detected during the reaction. The solid support of laponite not only alters the photochemical properties of Fe(bpy)₃²⁺ but also provides a rigid microenvironment for the enrichment of local substrate molecules and thus enhances the interaction of the active center with the substrate.     

氨基树脂对SiO2/有机硅杂化硬质涂料性能的影响

以正硅酸乙酯(TEOS)和有机硅氧烷为主要原料,采用溶胶-凝胶(sol-gel)技术合成透明的SiO2/有机硅溶液,引进氨基树脂在聚碳酸酯(PC)表面上制备硬质的硅/胺杂化薄膜。考察了氨基树脂用量对SiO2/有机硅涂料性能的影响,并采用红外光谱(IR)、紫外光谱(UV)、热重分析(TG)、粒径分析仪和扫描电镜(SEM)等方法对硅/胺杂化涂料进行了表征。结果发现,硅/胺杂化树脂胶粒的粒径为162 nm。添加少量的氨基树脂能够明显改善涂膜的耐碱性能,在碱液中浸泡24 h后,薄膜的透光率为90.7%,对PC基材仍具有一定的增透作用。杂化固化膜呈均相致密结构。当w(氨基树脂)=2%时,薄膜对PC基材的附着力为1级,铅笔硬度为2H。氨基树脂的添加使硬质薄膜的热稳定性有所降低。     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.