Stabilized dispersions of titania nanoparticles via a sol–gel process and applications in UV‐curable hybrid systems

Organic–inorganic hybrid UV‐curable coatings were synthesized through blending UV‐curable components and stabilized titania sol prepared via a sol–gel process of tetrabutyl titanate (TBT) with three different stabilizers, acetylacetone (Acac), isopropyl tri(dioctyl)pyrophosphato titanate coupling agent (TTPO) and a polymerizable organic phosphoric acid (MAP). The size and the dispersion of titania particle in the UV‐cured organic matrix were dominated by the properties of these stabilizers. A cured hybrid film with titania particle size around 20 nm was obtained when TTPO was utilized as protection agent for the sol. It is interesting that the hardness and flexibility of the photocured hybrid films were improved simultaneously, in contrast to results with neat organic UV‐curable formulations. Copyright © 2006 Society of Chemical Industry     

Novel organic–inorganic chemical hybrid fillers for dental composite materials

A series of new polymethacrylate–silica chemical hybrid dental fillers has been prepared by the sol–gel reactions of poly[methyl methacrylate-co-3-(trimethoxysilyl) propyl methacrylate] or poly[3-(trimethoxysilyl)propyl methacrylate] with tetraethyl orthosilicate at various compositions. In these hybrid fillers, the polymethacrylate chains are uniformly distributed in and covalently bonded to the silica networks at molecular level without macroscopic organic–inorganic phase separation. The contact angle and surface tension parameters indicate that the hybrid fillers have better wetting properties with the 2,2-bis(p-2-hydroxy-3-methacryloxypropoxyphenyl)propane/triethyleneglycol dimethacrylate resin and stronger interfacial bonding with the polymer matrix than pure silica fillers. The compressive testing results demonstrate that the dental composites prepared with the hybrid fillers tend to have enhanced mechanical properties in comparison to those with the silane-treated fused silica and the pure sol-gel silica fillers at the same silica content. Scanning electron micrographic study reveals that upon compressive tests the dental composites with the hybrid fillers have fewer failures at the filler–matrix interface than those with pure silica fillers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1689–1699, 1998     

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     

Relation between the scratch resistance and the chemical structure of organic–inorganic hybrid coatings

Organic–inorganic hybrid materials can be defined as materials combining organic and inorganic domains in a nanometric scale. The development of these organic–inorganic hybrids has achieved properties from both organic and inorganic materials.     

Preparation and characterization of UV‐curable MPS‐modified silica nanocomposite coats

A series of UV‐curable nanocomposites were prepared with 3‐(trimethoxysilyl) propyl methacrylate (MPS) modified nanosilica under the initiation of 2,2‐dimethoxy‐1,2‐diphenylethan‐1‐one. It was found that MPS‐modified nanosilica together with free MPS could form transparent nanocomposite coats. As the particle size of nanosilica increased, the photopolymerization rate, final double bond conversion, and tack‐free time of nanocomposites increased while the surface roughness, glass‐transition temperature, and UV absorbance of nanocomposites decreased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2274–2281, 2005     

Nanocomposite coatings via simultaneous organic–inorganic photo‐induced polymerization: synthesis,structural investigation and mechanical characterization

Hybrid sol–gel films were prepared via a simultaneous organic‐inorganic UV‐curing process using a diaryliodonium salt as a superacid photogenerator. In this single‐step procedure, an epoxy functionalized reactive resin mixed with a variable amount of either of two epoxy trialkoxysilane precursors was UV‐irradiated, causing both the initiation of epoxy ring‐opening copolymerization and the catalysis of trialkoxysilyl sol–gel reactions. The concomitant photo‐induced sol–gel process was found to have a significant effect on the two related propagation mechanisms in competition for the oxirane ring‐opening—the active chain‐end and the activated monomer mechanisms—as proved by a systematic examination of the hybrid material microstructure through ²⁹Si and ¹³C solid‐state NMR spectroscopy. The effect of the oxo‐silica network generation on the epoxy reaction kinetics was also evaluated using real‐time Fourier transform infrared spectroscopy upon varying the epoxysilane structure and its concentration. Thermal and dynamic mechanical analyses were systematically performed on these hybrids, by studying thoroughly their structure–property interdependence. Other mechanical characterizations through tribological and scratch tests suggested that the present photopolymer–silica hybrid material provides a powerful tool to tailor mechanical property profiles. Copyright © 2010 Society of Chemical Industry     

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.     

Electrical behavior of PET films coated with nanostructured organic–inorganic hybrids

Hybrid coatings, based on poly(ethylene oxide) (PEO) or polycaprolactone (PCL) and silica (SiO₂), at different organic–inorganic compositions have been used to coat PET films employed in the electric industry to produce capacitors. The overall electrical behavior of the coated films has been investigated. The electrical strength of the coated films increases up to 10–15% of the uncoated ones regardless of polymer type (PEO/PCL) and amount of inorganic phase, as far as the thickness of the coating is below 5 μm. A systematic increase of surface electrical conductivity is found in all coated samples which however still behave as insulators. Permittivity and loss factor also increase particularly at low frequencies (< 10 Hz) on account of the presence of ions deriving from the sol–gel process and on the presence of interfacial polarization probably related to the coatings nanostructurated morphology which leads to phase separation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4870–4877, 2006     

Preparation and evaluation of epoxy methacrylate UV‐curable coatings containing phthalazinone

Epoxy methacrylate resin (EMA) UV‐curable coatings exhibit high reactivity, low viscosity and excellent chemical resistance in environmentally friendly coatings. A novel EMA containing phthalazinone moieties for high temperature resistant UV‐curable coatings was synthesized. The formulations were cured with hexanediol diacrylate (HDDA) and trimethylol propane triacrylate (TMPTA) as reactive diluents promoted by a photoinitiator, and then interpenetrating polymer networks were generated. The mechanical, chemical and thermal properties of the clear coatings were characterized using Chinese National Standard methods (GB). EMA was used with UV radiation curing in combination with 6.7 wt% of HDDA and 13.4 wt% of TMPTA, and the properties of the cured films were as follows: pencil hardness of 5 H, 30% NaOH resistance for 30 days, 15% HCl resistance for 10 days, 3% NaCl resistance for 30 days and 5% weight loss temperature of 300.5 °C. EMA UV‐curable coatings containing phthalazinone exhibit excellent chemical and thermal stability, and could be potential candidates for UV‐curable zero volatile organic compound coatings applied in the fields of salt spray corrosion, strong radiation and high‐temperature resistance. Copyright © 2009 Society of Chemical Industry     

New anion exchanger organic–inorganic hybrid materials and membranes from a copolymerof glycidylmethacrylate and γ‐methacryloxypropyl trimethoxy silane

Organic–inorganic hybrid materials and mem branes were prepared through coating on Teflon plate or dip‐coating on microporous alumina substrates with the solution of glycidylmethacrylate (GMA) and γ‐methacryloxypropyl trimethoxy silane (γ‐MPS) copolymer, followed by ring‐opening of the GMA moiety with trimethylamine hydrochloric and sol–gel reaction of the γ‐MPS moiety. Composition of the GMA and γ‐MPS copolymer was varied by changing the feed ratio of GMA to γ‐MPS during the copolymerization. So the thermal stability, hydrophilicity, electrical properties, etc. of the hybrid materials and membranes were varied. Results showed that as the γ‐MPS amount increased in the copolymer, T_d (the temperature on thermogram at 5% weight loss) value of the hybrid materials and water contact angle of the hybrid membrane generally increased, while the anion exchange capacity, water uptake (W_R) and pure water flux decreased. The charge transition point of the hybrid membranes deduced from their streaming potential behavior decreased from pH > 12 to pH = 7–8 as the γ‐MPS amount increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3580–3589, 2006     

Effects of preparation method on microstructure and properties of UV‐curable nanocomposite coatings containing silica

UV‐curable nanocomposites were prepared by the blending method or the in situ method with nanosilica obtained from a sol–gel process. The microstructure and properties of the nanocomposite coatings were investigated using ²⁹Si‐NMR cross‐polarization/magic‐angle spinning, transmission electron microscopy (TEM), Fourier transform IR (FTIR), differential scanning calorimetry (DSC), and UV–visible (UV–vis) spectra, respectively. The NMR and TEM showed that during the blending method, tetraethyl orthosilicate (TEOS) completely hydrolyzed to form nanosilica particles, which were evenly dispersed in the polymer matrix. However, for the in situ method, TEOS partially hydrolyzed to form some kind of microstructure and morphology of inorganic phases intertwisted with organic molecules. FTIR analysis indicated that the nanocomposites prepared from the in situ method had much higher curing rates than those from the blending method. DSC and UV–vis measurements showed that the blending method caused higher glass‐transition temperatures and UV absorbance than the in situ method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1119–1124, 2005     

Preparation of organic–inorganic nanocomposites with core‐shell structure by inorganic powders

Organic–inorganic nanocomposites with core‐shell structure were prepared in two steps. In the first step, the latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of methacrylic acid (MAA), were prepared. Small amounts of acrylic acid incorporated into the latex to have better interaction between the surface of particles and inorganic phase. MAA also increased the latex stability and decreased the amount of coagulum. In the second step, the core‐shell structures were prepared by coating the latex particles with three types of inorganic powders. Pectin coated precipitated calcium carbonate, alumina, and silica. The examinations show that pectin‐coated calcium carbonate has the best response than other types of calcium carbonate. Alumina was the second type of inorganic powder that was used for coating the core particles. Silicagel and fumed silica (Aerosil) were used for coating by silica. Scanning electron microscopy and transmission electron microscopy showed the particle morphology and the core‐shell structure, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

UV‐curable nanocomposites containing zirconium vinylphosphonate or zirconia

UV‐cured nanocomposite films were prepared from acrylic monomer and two types of nanomaterial: zirconium vinylphosphonate and zirconia, in the presence of a photoinitiator. The films were characterized by FTIR, SEM, and AFM. FTIR spectra showed the disappearance of band assigned to the CC group both of monomer and zirconium vinylphosphonate by polymerization and the presence of the phosphonate group in polymer. The influence of zirconium vinylphosphonate and zirconia content on thermooxidative degradation of polymeric films was studied by thermogravimetry. SEM and AFM images showed that nanomaterials are dispersed in polymer matrix with no macroscopic phase separation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of dendritic poly(amidoamine)‐silica gel hybrids

Novel dendrimer‐silica gel hybrids were prepared from amino‐terminated poly(amidoamine) generation 3 (32 cascade) and its partly ester‐terminated derivatives with tetraethoxysilane in the presence of a coupling agent 3‐glycidoxypropyltrimethoxysilane by in situ sol‐gel process. The scanning electron micrograph spectra showed that these transparent hybrids have the nanocomposite structure. Their transparent and thermal properties were characterized by ultraviolet, thermogravimetric analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2186–2190, 2000     

Submicrometer characterization of surfaces of epoxy‐based organic–inorganic nanocomposite coatings. A comparison of AFM study with currently used testing techniques

Surface properties (morphology, hardness) of transparent colorless epoxy‐based organic–inorganic nanocomposite coatings were investigated by atomic force microscopy, optical and scanning electron microscopy, nanoindentation, and the Persoz pendulum test. Friction and wear coefficients were obtained from tribological experiments. The influence of mechanical properties and the size, shape, and concentration of additives (colloidal silica particles and montmorillonite sheets) on the measured surface characteristics are discussed. It was found that the highest surface hardness (assigned by nanoindentation, pendulum test or expressed as the scratch resistance) exhibited materials with the glass‐transition temperature close to 20°C. Microcopy techniques revealed that surface morphology is influenced by both types of admixtures: on the nanometer scale by colloidal silica particles and on micrometer scale by montmorillonite platelets. Already 1 wt % of montmorillonite increased friction coefficients and wear resistance without distinctive changes of tensile properties. However, the addition of ? 20 wt. % of silica nanoparticles was necessary for the increase of wear and scratch resistances. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5763–5774, 2006     

Synthesis and characterization of nanocomposite of polyimide–silica hybrid from nonaqueous sol–gel process

Polyimide–silica (PI–SiO₂) hybrids with a nanostructure was obtained using the nonaqueous sol–gel process by polycondensation of phenyltriethoxysilane in a polyamic acid solution. Self‐catalyzed hydrolysis of phenyl‐substituted akoxysilane and modification on the polyimide structure are applied and result in highly compatible PI–SiO₂ hybrids. Transparent PI–SiO₂ with a high silica content of about 45% was thus obtained. The prepared PI–SiO₂ films were characterized by infrared spectrometry, ²⁹Si‐NMR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. These characterizations showed the silica influence on the properties of the hybrid. The thermal expansion coefficient of the PI–SiO₂ and the temperature correlation were also established for probing the potential for application. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1609–1618, 2000     

Synthesis of organic–inorganic hybrid polymeric nanocomposites for the hard coat application

An organic–inorganic hybrid polymeric nanocomposite has been synthesized for making UV‐curable hard coats. This nanocomposite consists of nano‐sized colloidal silica functionalized with vinyltriethoxysilane (VTES) and dendritic acrylic oligomers (DAO) which have been formed earlier via a reaction of ethylenediamine (EDA) with trimethylopropane triacrylate (TMPTA). Applied as a hard coat on top of a polyethylene terephthalate (PET) film, this nanocomposite has a short UV‐cure time and the cured coat has an enhanced thermal decomposition temperature (T_d), 89–90% transparency, increased hardness up to 3H, better adhesion up to 4B, and a flat surface with a root mean square roughness of 2–4 nm. The preparation as well as the characterization of the constituting species and the final hybrid are described in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3985–3993, 2007     

Grafted 2‐chloroethylphosphonic acid on inorganic supports used as flame retardant for unsaturated polyester resins

Flame retardants (FRs) are used for in protection against fire. Organic–inorganic hybrids could become one of the most promising FR solution in the future. In this paper, the synthesis, the characterization and the use as FRs and filler of grafted titania and alumina with 2‐chloroethylphosphonic acid are presented. These hybrids contain 3.8–3.24% P and have good flame retardance when they are incorporated into unsaturated polyester resins. Alumina treated with 2‐chloroethylphosphonic acid performed better than titania. The advantage of this approach is the use of these hybrid materials as filler and FR, in the same time, and the increase in flame retardancy by synergistic effect between alumina phosphorus and chlorine, for unsaturated polyester resins. Copyright © 2010 John Wiley & Sons, Ltd.     

Polymer–organoclay hybrids by polymerization into montmorillonite‐vinyl monomer interlayers

A different series of polymer–clay hybrid materials have been prepared by modification of the clay with different vinyl monomers, followed by polymerization of different ratios of vinyl monomers–clay with the monomers, such as methyl methacrylate, hydroxyethyl methacrylate, and styrene‐maleic anhydride. The materials were investigated by IR, which confirmed the intercalation of vinyl‐cation within the clay interlayers, and by TGA, which illustrated that phosphonium cation has high thermal stability than ammonium cation. Swelling studies of these materials in different organic solvents showed that the swelling degree increases as clay ratio decrease, and also showed higher swelling relative to vinyl–clay. X‐ray diffraction illustrated that the nanocomposites were exfoliated up to a 25 wt % content of organoclay relative to the amount of polymer. SEM and TEM examined the micrograph, which showed a good dispersion of the polymers into clay galleries, and formation of nanosize particles ranged 150–300 Å. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and characterization of fluorinated organic–inorganic hybrid coatings on tinplate

Fluorinated organic–inorganic hybrid coatings with interpenetrating network for corrosion protection of tinplate were prepared by hydrolysis and condensation reaction of tetraethoxysilane and 3‐methacryloxypropyltrimethoxysilane, followed by radical polymerization of trimethylolpropane triacrylate dodecafluoroheptyl methacrylate. The highly crosslinked organic network was developed and attached to the inorganic moieties through covalent Si–C bonds. The hybrid coatings were characterized by scanning electron microscope, water contact angle, Fourier transformed infrared spectroscopy, and thermogravimetric analysis. Their anticorrosion performances were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray test. The results indicated that the fluorinated hybrid coatings exhibited excellent anticorrosion ability by forming a hydrophobic physical barrier between tinplate substrate and its external environment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42428.