Micrometer and nanometer-scale parallel patterning of ceramic and organic–inorganic hybrid materials

This review gives an overview of the progress made in recent years in the development of low-cost parallel patterning techniques for ceramic materials, silica, and organic–inorganic silsesquioxane-based hybrids from wet-chemical solutions and suspensions on the micrometer and nanometer-scale. The emphasis of the discussion is placed on the application of soft-lithographic methods, but photolithography-aided patterning methods for oxide film growth are also discussed. In general, moulding-based patterning approaches and surface modification-based patterning approaches can be distinguished. Lateral resolutions well below 100 nm have been accomplished with some of these methods, but the fabrication of high-aspect ratio patterns remains a challenge.     

Preparation and characterization of photopolymerizable organic–inorganic hybrid materials by the sol-gel method

A series of UV-curable organic–inorganic hybrid materials were prepared by the sol-gel technique and coated onto Plexiglass^® substrate. The effects of the content of EGDMA and the content of the inorganic part on various properties of the coatings, such as tensile strength, hardness, gloss, and cross-cut adhesion, were investigated. It was found that the properties of the coating were improved by the addition of an inorganic part. The thermal properties of the hybrids were enhanced by incorporating silane sol into the organic part. Furthermore, it was found that the coating containing silica had a higher char content at 800 °C than the coating without silica. SEM studies indicated that nanosized (about 50 nm) silica particles were evenly dispersed throughout the organic matrix. A photo-DSC investigation showed that the organic coating polymerized more quickly than the hybrid coating.     

Synthesis and characterization of hybrid organic–inorganic materials based on sulphonated polyamideimide and silica

The preparation of hybrid organic–inorganic membrane materials based on a sulphonated polyamideimide resin and silica filler has been studied. The method allows the sol–gel process to proceed in the presence of a high molecular weight polyamideimide, resulting in well dispersed silica nanoparticles (<50 nm) within the polymer matrix with chemical bonding between the organic and inorganic phases. Tetraethoxysilane (TEOS) was used as the silica precursor and the organosilicate networks were bonded to the polymer matrix via a coupling agent aminopropyltriethoxysilane (APTrEOS). The structure and properties of these hybrid materials were characterized via a range of techniques including FTIR, TGA, DSC, SEM and contact angle analysis. It was found that the compatibility between organic and inorganic phases has been greatly enhanced by the incorporation of APTrEOS. The thermal stability and hydrophilic properties of hybrid materials have also been significantly improved.     

Preparation and use of hybrid organic–inorganic catalysts

Various approaches towards the immobilization of molecular homogeneous catalysts are introduced, focusing on catalysts where an organic molecule is attached to the surface of an inorganic support material via a covalent bond forming the so-called hybrid organic–inorganic catalysts. The application of this new class of catalysts in a wide variety of organic reactions is reviewed.     

New highly conductive organic–inorganic hybrid electrolytes based on star-branched silica based architectures

A new type of organic–inorganic hybrid electrolyte has been developed by a sol–gel process through the reaction of cyanuric chloride with poly(oxyalkylene) diamine and 3-isocyanatepropyltriethoxysilane, followed by co-condensation of 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane. A maximum ionic conductivity of 1.0 × 10^?4 Scm^?1 at 30 °C has been achieved with the solid hybrid electrolyte. The results of solid-state NMR not only confirm the structural framework of the hybrids, but also provide a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. The hybrid materials are blended with PVdF-HFP to form the blend hybrid membrane, followed by plasticization with various electrolyte solvents, with the purpose of increasing ionic conductivity. The plasticized blend hybrid electrolyte exhibits a maximum room temperature ionic conductivity of 8.8 × 10^?3 Scm^?1. Such a high ionic conductivity allows it as a potential candidate for applications in lithium ion batteries.     

New luminescent lanthanide centered Si–O–Ti organic–inorganic hybrid material using sulfoxide linkage

A new sort of chemically bonded lanthanide organic–inorganic hybrid material has been constructed through the bifunctional sulfoxide molecular bridge (MSAPSi, which is functionalized 2-(methylsulfinyl) acetophenone (MSAP) by 3-(triethoxysilyl)-propyl isocyanate (TESPIC)) linking Si–O–Ti–O inorganic networks. The results suggest that the obtained hybrid materials are totally amorphous without phase separation phenomenon and exhibit the characteristic luminescence of Eu³⁺ and Tb³⁺ ions. Furthermore, the decay times and emission quantum efficiency of Eu³⁺ hybrid material are also determined.     

UV-curable nano-silver containing polyurethane based organic–inorganic hybrid coatings

The preparation of nano-silver containing polyurethane based UV-curable organic–inorganic hybrid coatings that have antibacterial activity is presented in this paper. Trimethoxysilane end-capped bis[(4-β-hydroxyethoxy)phenyl] methyl phosphine oxide urethane was synthesized as a coupling agent and used to improve the compatibility between the organic and inorganic phases of the hybrid coating. Due to its strong antibacterial activity, silver nanoparticles were prepared and added to the nanocomposite formulations. The relationships between the amount of coupling agent and the final coating properties were investigated. The hybrid coatings presented good thermal stability. Tests for abrasion, hardness, gloss, and adhesion of the coatings were also performed. The morphological investigation was performed by SEM to determine the size of the silver nanoparticles. The nano-silver containing coatings exhibited good antibacterial activity against E. coli and S. aureus.     

Hybrid organic–inorganic materials as coatings for protecting wood

A new coating based on organic–inorganic materials was prepared using concurrent sol–gel and polymerization techniques, and applied to wood using a dip coating method. Vinyl-functionalized zirconium oxoclusters were co-polymerized with vinyltrimethoxysilane on wood. The coating process was examined, also assessing the specific weight of hybrid polymer left on the wood after one or two coating steps. The efficacy of the process in consolidating and protecting the wood was investigated using high-temperature differential scanning calorimetry (DSC), environmental scanning electron microscopy (ESEM), infrared spectroscopy and solid state NMR spectroscopy. The coating did not affect the morphology and appearance of the wood. However, it did modify its behavior on exposure to fire and preliminary accelerated biological tests with the brown rot fungus Coniophora puteana showing an improved resistance to the fungal attack.     

Polymerization of hybrid organic–inorganic materials from several silicon compounds followed by TGA/DTA,FTIR and NMR techniques

Hybrid organic–inorganic films have been prepared by hydrolysis and condensation of several silicon compounds: 3-methacryloxypropyltrimethoxysilane (MPTS) or methyltriethoxysilane (MTES) and tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS) precursors using four [TEOS] or [TMOS]/[MPTS] or [MTES] molar ratios: 0, 0.5, 1 and 2.     

Influence of silane structure on curing behavior and surface properties of sol–gel based UV-curable organic–inorganic hybrid coatings

In this study, three usual silane precursors, tetraethoxysilane (TEOS), vinyltrimethoxysilane (VTMS), and 3-methacryloxypropyltrimethoxysilane (MPS), and different binary and triplet blends of them were polymerized via a sol–gel method under acidic conditions. ²⁹Si NMR spectroscopy was used to characterize and quantify the degree of condensation of oligomers. The organic phase was based on a three-acrylate monomer trimethylolpropane triacrylate (TMPTA). The effect of prepared oligomers on the curing behavior of hybrid materials and the interaction between organic and inorganic phases were monitored via photo differential scanning calorimetry (Photo-DSC). Atomic force microscopy (AFM) was used to investigate the surface properties of UV-cured hybrid materials. Photo-DSC results showed that the addition of functionalized oligomers can increase both the photopolymerization rate and the final degree of conversion. They also indicated that oligomers containing MPS are more compatible with the organic phase than other oligomers. Topography and phase trace images of AFM showed that oligomers containing VTMS migrate to the surface of films and affect the water contact angle. In contrast to VTMS, the presence of MPS in oligomers causes the formation of covalent bonds between the organic and inorganic phases in the bulk of the film, and so the surface properties of the film remain unchanged.     

Polydimethylsiloxane (PDMS)-based antibacterial organic–inorganic hybrid coatings

UV-curable antibacterial organic–inorganic hybrid coatings were prepared by sol–gel method. Triethoxysilane-terminated poly(dimethylsiloxane) (TESi-PDMS) as a new coupling agent to improve the compatibility between organic and inorganic phases was synthesized. PDMS-based urethane methacrylate oligomer was obtained by reacting isophorone diisocyanate with hydroxyethyl methacrylate and hydroxyl-terminated PDMS. The formulations were applied onto polycarbonate panels and then cured by UV radiation. Physical properties of UV-cured free films such as gel content, stress–strain, and conversion of acrylate double bond were examined. In addition, the antibacterial effects of the coatings were investigated. Nanosilver-containing formulations exhibited high antibacterial effect against Escherichia coli and Staphylococcus aureus. Thermogravimetric analysis indicated that thermal stability of the hybrids was significantly higher than the organic polymer. Contact angle measurement showed that addition of silane precursor increased the contact angle from 95° to 110°.     

Weatherability of hybrid organic–inorganic silica protective coatings on glass

Currently, there is a growing interest in the application of silicon-based technologies for the development of advanced hybrid organic–inorganic coatings with strong weatherability. In this study, the sol–gel process is used to prepare such coatings on glass and their resistance to weathering effects is assessed afterwards. Various sols were prepared by mixing a silica-based inorganic matrix (tetraethyl orthosilicate) with different quantities of silica alkoxides functionalised with various organic groups. Subsequently, the sols were dip-coated onto glass samples at low temperatures without any heat treatment. The coatings prepared were analysed before and after three model ageing tests simulating various weathering parameters. After ageing, the best performing coatings showed good overall homogeneity and transparency (optical microscopy, SEM), improved water repellency and adhesion to the glass substrate (static contact angle measurements, cross-cut tape tests) and no colour or chemical composition changes (UV–VIS, FTIR). Compared with commercial hybrid silica products, the alkyl- and methacryloxy-functionalised silica coatings particularly displayed improved homogeneity, elasticity and barrier properties. Thus, these low temperature coatings, easily applicable to thin films, appear to fulfil the main requirements for the protection of the glass exposed to weathering phenomena.     

An inorganic–organic hybrid zinc phosphite framework with unusual topology

Employing piperazine (= ppz) as a bridging ligand, a new three-dimensional (3D) inorganic–organic hybrid zinc phosphite framework [Zn₂(HPO₃)₂(ppz)]_n (1) has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction. The structure of 1 features a pillared-layer framework with unusual (3,4)-connected dmc topology. The results demonstrate that it is possible to add organic ligands into an open zinc phosphite framework for the construction of hybrid materials.     

Robust multifunctional superhydrophobic organic–inorganic hybrid macroporous coatings and films

We demonstrate a facile and efficient method for fabricating multifunctional superhydrophobic organic–inorganic hybrid macroporous coatings and films with robust environmental stabilities involving the electrospinning of phenylsilsesquiazane (PhSSQZ) in the presence of polystyrene (PS). The resulting freestanding PhSSQZ/PS webs, which featured hierarchical fibrous structures with the unique chemical properties of PhSSQZ, provided a practical material with potential uses in many applications including structural coatings, oil–water separation membranes, and high-performance air filters. The materials maintained their fibrous structures and superhydrophobicity even after heat treatment at 600 °C under an ambient atmosphere, which is among the highest level reported up to date for solution-processed superhydrophobic surfaces with soft materials. The solvent resistance and mechanical strength of the PhSSQZ/PS webs were significantly enhanced through the structured siloxane network due to thermally induced hydrolysis of PhSSQZ and condensation of the resulting silanols. The properties of this novel material suggest that the present approach will advance our knowledge and capability to design and develop multifunctional smart materials with robust superhydrophobicity and macroporosity.     

Three-components organic–inorganic hybrid materials as protective coatings for wood: Optimisation,synthesis, and characterisation

The present work explores new solutions for the development of functional flame-resistant hybrid coatings for wood, by using oxocluster-reinforced hybrid materials. Hybrid coatings and bulk materials were produced by photopolymerisation of 3-methacryloxypropyltrimethoxysilane (MAPTMS) with methylmethacrylate (MMA) in the presence of the dimeric oxocluster (Zr₆O₄(OH)₄(OOCCH₂CHCH₂)₁₂(n-PrOH)]₂·4(CH₂CHCH₂COOH), (Zr12), characterised by the presence of 12 vinylacetate groups for each molecules. The molar ratios among silane, MMA monomer and oxocluster were changed to optimise the best performing formulation. The final molar ratio chosen for the spray deposition of the coatings under inert atmosphere and for the preparation of the bulk specimens was MAPTMS:MMA:Zr12 = 1:3:0.008. Attenuated Total Reflectance-Fourier Transform Infra Red (ATR-FTIR) spectroscopy and Differential Scannig Calorimetry (DSC) were used in time-resolved fashion to optimise the photopolymerisation time, resulting to be 20 min. The polymerisation of the organic part and the condensation of the siloxane groups were investigated by the combined use of DSC, Fourier Transform Infra-Red (FTIR) and solid state Nuclear Magnetic Resonance (NMR) spectroscopies, showing that, whereas a complete organic polymerisation degree was reached, the condensation of the silica component was not completed. Dynamical Mechanical Spectroscopy (DMS) evidenced that: (1) the copolymerisation of the silane with the Zr12 oxocluster without MMA yields materials with very poor mechanical thermo-properties; (2) the Zr12 oxocluster copolymerised with MMA gives very stiff but fragile hybrids; (3) the ternary system yields instead flexible materials, which are endowed with outstanding thermo-mechanical properties. The optimised formulation was used for the deposition of coatings on wood (Larex), which were analysed by Scanning Electron Microscopy (SEM), contact angles measurements and tested toward flame-resistance.     

Preparation of a new nano-layered materials and organic–inorganic nano-hybrid materials, Zn–Si LDH

Layered double hydroxides are nano-ordered layered compounds. Layered double hydroxide (LDH) well known for its ability to intercalate anionic compounds has been prepared conventionally only with divalent and trivalent cations. In this study, Zn–Si LDH consisting of divalent and tetravalent cations was prepared, and reacted with organic acids and formed nano-hybrid materials. X-Ray diffraction patterns of the prepared LDH (Zn–Si–CO₃) showed that interlayer spacing of the LDH was 0.67 nm and increased to be 4.2 nm in the case of stearate anion as the guest. The spacing 0.67 nm was small compared to the usual LDH (Zn–Al–CO₃) of 0.76 nm in the case of carbonate anion as the guest. Also, DTA, TG and DTG analyses indicated that the electrostatic force between the layers and carbonate anions increased where the carbonate anions in Zn–Si LDH decomposed at 259 °C while those in Zn–Al–CO₃ decomposed at 230–240 °C.     

Negatively charged organic–inorganic hybrid silica nanofiltration membranes for lithium extraction

Effective extraction of lithium from high Mg~(2+)/Li+ratio brine lakes is of great challenge. In this work, organic–inorganic hybrid silica nanofiltration(NF) membranes were prepared by dip-coating a 1,2-bis(triethoxysilyl)ethane(BTESE)-derived separation layer on tubular TiO_2 support, for efficient separation of LiC l and MgCl_2 salt solutions. We found that the membrane calcinated at 400 °C(M1–400) could exhibit a narrow pore size distribution(0.63–1.66 nm) owing to the dehydroxylation and the thermal degradation of the organic bridge groups. All as-prepared membranes exhibited higher rejections to LiCl than to MgCl_2, which was attributed to the negative charge of the membrane surfaces. The rejection for LiCl and MgCl_2 followed the order: LiCl N MgCl_2, revealing that Donnan exclusion effect dominated the salt rejection mechanism. In addition, the triplecoated membrane calcined at 400 °C(M3–400) exhibited a permeability of about 9.5 L·m~(-2)·h~(-1)·bar~(-1) for LiCl or MgCl_2 solutions, with rejections of 74.7% and 20.3% to LiCl and MgCl_2,respectively, under the transmembrane pressure at 6 bar. Compared with the previously reported performance of NF membranes for Mg~(2+)/Li+separation, the overall performance of M3–400 is highly competitive. Therefore, this work may provide new insight into designing robust silica-based ceramic NF membranes with negative charge for efficient lithium extraction from salt lakes.     

Synthesis of high performance organic–inorganic composite via click coupling of block polymer and polyhedral oligomeric silsesquioxane

Novel hybrid systems based on poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) and a polyhedral oligomeric silsesquioxane (POSS) have been synthesized via click chemistry. Different compositions of SEBS-functionalized POSS were obtained from the reaction of azide-functionalized styrene units of SEBS with alkyne-functionalized POSS molecules. Characterization of SEBS-functionalized POSS by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance spectroscopy revealed that the POSS molecules were successfully attached to the phenyl group of the SEBS polymer chain following the click reaction. Homogeneous dispersion of POSS molecules in the polymer matrix was demonstrated by scanning electron microscopy. The POSS molecule showed excellent compatibility with polymer matrix, and as a consequence the remarkable enhancement of mechanical properties (breaking stress = 44%, modulus = 285%) and thermal stability for the resulting composite films was achieved. The reinforcing effect is ascribed to both the compatible homogeneous dispersion of POSS in the matrix and the covalent bond between SEBS and POSS molecules arising from the click coupling.     

Synthesis of some novel silicone-imide hybrid inorganic–organic polymer and their properties

Synthesis and properties of poly(imide-siloxane) hybrid polymers (PIS), having alternate diimide and disiloxane units, based on 1,3-bis(succinyl anhydride)1,1,3,3-tetraorganodisiloxane (I or II) have been described. Polymers have been synthesized by the precursor synthesis i.e., poly(amic acid), using siloxanes (I or II) and 4,4′-diaminodiphenylmethane (DDM) or 4,4′-diaminodiphenylsulphone (DDS) in N,N-dimethylacetamide (DMAc) followed by thermal imidization. FT-IR, thermal (TGA and TMA), solvent resistant and dielectric properties of the compounds have also been studied. The glass transition, thermal stability and char yields of these hybrid polymers increased appreciably. These materials also showed very good solvent resistant properties in protic and aprotic solvents.