Synthesis and properties of conducting organic/inorganic polyurethane hybrids

A series of polyurethane/polyaniline/silica organic/inorganic hybrids were synthesized via the conventional polyurethane (PU) prepolymer technique. Amine-endcapped polyaniline (PANI) with low molecular weight and higher solubility was firstly synthesized. This PANI oligomer was then used together with nano-silica bearing silanol groups as chain extenders to prepare the conducting polyurethane hybrids. The polyurethane hybrids were designated as PU-xPANI-ySiO₂ (x + y = 1). For comparison, the urethane-aniline block copolymer and the PU/silica hybrid were designated as PU-PANI and PU-SiO₂, respectively.The structures of PU-PANI, PU-SiO₂ and conducting polyurethane hybrids were confirmed by FT-IR, solid-state ¹³C, and ²⁹Si NMR spectra. In nano-silica containing organic/inorganic conducting polyurethane hybrids, UV-vis spectra revealed the maximum absorption bands similar to that of PU-PANI. X-ray diffraction patterns indicated that these samples are typical of semicrystalline/amorphous materials. SEM image of PU-0.5PANI-0.5SiO₂ showed that PANI was dispersed homogeneously and interconnected continuously in the insulating PU-silica matrix. TGA results of the polymer hybrids exhibited higher thermal stabilities and lower decomposition rates than that of PU-PANI both in nitrogen and air. Differential scanning calorimetry (DSC) studies indicated that the polyurethane hybrids had higher glass-transition temperatures (T_g) with the increase of PANI, but lower than that of PU-PANI. Stress-strain curves for all of the polyurethane hybrids showed the elastomeric behavior of typical polyurethanes. The surface resistivity values of all hybrids were about 10⁸ ∼ 10¹⁰ Ω/sq. and might meet the requirement of the anti-electrostatic materials.     

Nanoscale polyoxometalate‐based inorganic/organic hybrids

The latest advances in the area of polyoxometalate (POM)‐based inorganic/organic hybrid materials prepared by self‐assembly, covalent modification, and supramolecular interactions are presented. This Review is composed of five sections and documents the effect of organic cations on the formation of novel POMs, surfactant encapsulated POM‐based hybrids, polymeric POM/organic hybrid materials, POMs‐containing ionic crystals, and covalently functionalized POMs. In addition to their role in the charge‐balancing, of anionic POMs, the crucial role of organic cations in the formation and functionalization of POM‐based hybrid materials is discussed. DOI 10.1002/tcr.201100002     

Reaction kinetics and network characterization of UV-curing polyester acrylate inorganic/organic hybrids

Polyester acrylate inorganic/organic hybrids were prepared using a sol-gel precursor, coupling agent, and reactive diluent. The hybrids were cured via a UV-free radical initiator. Design of experiments (DOE) was utilized to investigate reaction kinetics and complex variable interactions. The effects of the silicate groups on the free radical photo-curing reaction kinetics were investigated utilizing a time-resolved Fourier transform infrared (FT-IR) spectroscopy and a differential scanning calorimeter equipped with a photocalorimetric accessory (photo-DSC). Microgel and inorganic network formation during the UV-initiated free radical crosslinking reactions was suggested to describe the complex gel-point behavior. It was proposed that the formation of the inorganic silicate groups retarded the organic crosslinking reactions. The UV-cured inorganic/organic hybrid films exhibited more homogeneous film morphology compared to the organic counterparts. In the hybrid films, a core-shell like inorganic/organic particle morphology was observed. The UV-crosslinked organic phase forms the core, whereas, the inorganic silicate forms the surrounding shell.     

Miscibility and hydrogen-bonding behavior in organic/inorganic polymer hybrids containing octaphenol polyhedral oligomeric silsesquioxane

In this study, we investigated the miscibility behavior and mechanism of interaction of poly(methyl mechacrylate) (PMMA), poly(vinyl pyrrolidone) PVP, and PMMA- co-PVP blends with octa(phenol)octasilsequioxane (OP-POSS). For the PMMA/OP-POSS binary blend, the value of the association constant ( K A = 29) was smaller than that in the poly(vinyl phenol) (PVPh)/PMMA ( K A = 37.4) and ethyl phenol (EPh)/PMMA ( K A = 101) blend systems, implying that the phenol groups of the OP-POSS units in the PMMA/OP-POSS blends interacted to a lesser degree with the CO groups of PMMA than they did in the other two systems. In addition, the ionic conductivity of a LiClO4/PMMA- co-PVP polymer electrolyte was increased after blending with OP-POSS.     

Local structure and near-infrared emission features of neodymium-based amine functionalized organic/inorganic hybrids

Nd(3+)-based organic/inorganic hybrids have potential application in the field of integrated optics. Attractive sol-gel derived di-urea and di-urethane cross-linked poly(oxyethylene) (POE)/siloxane hybrids (di-ureasils and di-urethanesils, respectively) doped with neodymium triflate (Nd(CF(3)SO(3))(3)) were examined by Fourier transform mid-infrared (FT-IR), Raman (FT-Raman), (29)Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and photoluminescence spectroscopies, and small-angle X-ray scattering (SAXS). The goals of this work were to determine which cation coordinating site of the host matrix (ether oxygen atoms or carbonyl oxygen atoms) is active in each of the materials analyzed, its influence on the nanostructure of the samples and its relation with the photoluminescence properties. The main conclusion derived from this study is that the hydrogen-bonded associations formed throughout the materials play a major role in the hybrids nanostructure and photoluminescence properties.     

Coordination assembly and characterization of red-emitting europium (III) organic/inorganic polymeric hybrids

Novel luminescent ternary organic-inorganic-polymeric hybrid material has been assembled by Eu(3+) complex incorporating into poly (methyl methacrylate) (PMMA) matrix. The functionalized silylated precursor PDC-Si derived from PDC (2,6-pyridinedicarboxylic acid chloride) behaves as the coordination units of Eu(3+) ion. The organic polymer was introduced into the system by directly dissolving PMMA in solution of Eu(PDC-Si)(3) complex and N-N-Dimethyl Formamide (DMF) with subsequent addition of tetraethoxysilane to promote hydrolysis and condensation. The structure and photophysical properties of the resulting hybrids are characterized by Fourier transform infrared spectra, X-ray diffraction (XRD), scanning electronic microscopy and photoluminescence spectra. The luminescence quantum yield was calculated based on the emission spectra and luminescence lifetimes. XRD reveals its amorphous structure. Efficient energy transfer process occurs between PMMA and Eu(3+), and replacement of water molecule by PMMA in the first coordination sphere was confirmed by comparing with the binary hybrid.     

SiO2–poly(amidoamine) dendrimer inorganic/organic hybrids

SiO₂–poly(amidoamine) (PAMAM) dendrimer hybrids were synthesized via (1) a Michael addition reaction between the dendrimer and 3‐(trimethoxysilyl) propyl acrylate, (2) the dissolution of the formed compound in methanol, and (3) the mixing of the latter solution with a methanol solution of partly hydrolyzed tetraethylorthosilicate (TEOS) and its casting on a glass substrate. ¹H NMR indicated that in the first step, 77% of the secondary amines were converted into tertiary amines when the fourth‐generation dendrimer was employed and 46% were converted when the second‐generation dendrimer was used. The final SiO₂–PAMAM dendrimer hybrids were obtained via the hydrolysis and condensation of the compound obtained via the Michael addition and the methanol solution of partly hydrolyzed TEOS. The compartmentalized structure of the hybrids due to the compartments of the dendrimers could be controlled by changing the dendrimer and the amount of TEOS. Scanning electron microscopy and transmission electron microscopy micrographs provided information about the structure of the hybrids. Like the PAMAM dendrimer, the SiO₂–PAMAM dendrimer hybrids exhibited a high metal ion complexing capacity because of the presence of the compartments of the dendrimer; they can be, however, much more easily handled, and, as demonstrated by thermogravimetric experiments, have much higher thermal resistance. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1443–1449, 2000     

Optical filters and resonant cavities based on di-ureasil organic–inorganic hybrids

Sol–gel derived poly(oxyethylene)/siloxane organic–inorganic di-ureasil hybrids containing different amounts (20–60% mol) of methacrylic acid (McOH) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films and transparent and shape controlled monoliths. Laser direct writing was used to create channel waveguides, Bragg gratings, Fabry–Perot cavities and optical filters. The resulting Fabry–Perot optical cavity displays a free spectral range of 16.55 GHz and a fringe intensity contrast of 5.35 dB. Optical rejection values between 6.7 and 10.4 dB were obtained by varying the amount of the Zr-OMc oxo-clusters.     

Organic and inorganic nanoparticle hybrids

Viruses are exemplary models in nanoassembly for their regular geometries, well characterized surface properties, and nanoscale dimensions. Armed with versatile tools aimed at site-directed mutagenesis to modify the virion's surface, conjugation chemistry for capsid coupling, and manipulation of nanoparticles, we have demonstrated nanoscale assembly of inorganic carbon nanotubes and quantum dots with engineered viruses to produce an intimate array of hybrid structures.     

UV-light irradiation preparation of soybean residue-based hydrogel composite from inorganic/organic hybrids for degradable slow-release N-fertilizer

Research on Chemical Intermediates - Biomass waste, which was the by-product generated along with the production of food, was transformed into high-value constituent in slow-release fertilizers....     

Lanthanide-centered inorganic/organic hybrids from functionalized 2-pyrrolidinone-5-carboxylic acid bridge: Covalently bonded assembly and luminescence

A series of organic-inorganic hybrid material with chemically bonding have been prepared through the precursor (PDCA-Si) derived from 2-pyrrolidinone-5-carboxylic acid, which exhibits a self-organization cooperation interaction under the coordination to RE³⁺ (Eu³⁺, Tb³⁺). The pure organic silica hybrids (PDCA-Si) without RE³⁺ presents the small particle size and main blue luminescence with maximum peak 462 nm occupying a broad band from 425 to 550 nm. When Eu³⁺ and Tb³⁺ are introduced, the particle size of the hybrids increases, indicating the coordination effect has influence on the microstructure of hybrids. Besides, the corresponding Eu and Tb hybrids (Eu-PDCA-Si, Tb-PDCA-Si) show the characteristic red and green luminescence of Eu³⁺ and Tb³⁺, respectively, which suggests that the efficient intramolecular energy transfer process take place between carboxylic groups and lanthanide ions take place. The luminescence lifetimes and quantum efficiencies of them are determined and energy transfer efficiency between PDCA-Si and Eu³⁺ (Tb³⁺) is calculated.     

Multifunctional inorganic/organic hybrid microgels

This review summarizes recent research dedicated to hybrid colloids combining inorganic nanoparticles and cross-linked polymer networks. We discuss aspects of synthesis, characterization, and application of systems with different morphologies and properties. Due to the large number of works in the field of composite materials, we focus on materials with responsive polymer components, which are dispersed in aqueous media.     

Light-activated hybrid organic/inorganic antimicrobial coatings

Light-activated antimicrobial coatings were obtained by the covalently immobilizing photo-sensitizers in a hybrid organic/inorganic matrix. These coatings were deposited via sol-gel chemistry using epoxy and methyl functional silanes. The light-activated chromophores used in this study were Methylene Blue, Toluidine Blue O, and Rose Bengal. The immobilized photo-sensitizers did not leach from the coatings. The mechanically durable hybrid coatings comprising 2.5% by weight of Rose Bengal had a good adhesion to the glass surface. These coatings were tested for the photo-deactivation of Escherichia coli and Staphylococcus aureus using illumination by a commercial fluorescent lamp. Log reduction of E. coli and S. aureus were >4 when illuminated by the fluorescent lamp in 1 and 3?h, respectively. Due to its high mechanical durability and chemical resistance, such light-activated hybrid coatings are promising candidates for indoor applications in healthcare facilities.

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Microstructure and interface in organic/inorganic hybrid composites1

In this article, the characterization of the microstructure and interface of hybrid composites is discussed. Poly(p‐phenylene biphenyltetracarboximide) was used as a matrix polymer and tetraethoxysilane was a precursor of silica. Polyimide/silica hybrid composites were prepared by sol–gel reaction and thermal imidization. Interfacial interaction as well as microstructure in polyimide/silica hybrid composites were well characterized by atomic force microscopy topology and small‐angle X‐ray scattering measurements. In addition, fluorescence spectroscopy was successfully applied in the studies to reveal the interfacial interaction in the hybrid systems. Copyright © 2000 John Wiley & Sons, Ltd.     

Light-controlled organic/inorganic P-N junction nanowires

P-N junctions are of great importance both in modern electronic applications and in understanding other semiconductor devices. Organic/inorganic P-N junction nanowires composed of functional organic molecules and inorganic molecules may be able to realize new or improved chemical and physical properties that were not observed in the individual component on nanosize and their bulk materials. We report herein the fabrication of the organic/inorganic semiconductor P-N junction nanowire and the remarkable performance on the light-controlled diode within a single hybrid P-N junction nanowire. Controlling the conductivity of the P-N junction nanowire by the light irradiation simply to achieve diode work indicates a new way to realize the photoelectric integration in a single nanowire device.     

Characterizing multiphase organic/inorganic/aqueous aerosol droplets

The partitioning of an immiscible and volatile organic component between the gas and aqueous condensed phases of an aerosol is investigated using optical tweezers. Specifically, the phase segregation of immiscible decane and aqueous components within a single liquid aerosol droplet is characterized by brightfield microscopy and by spontaneous and stimulated Raman scattering. The internally mixed phases are observed to adopt equilibrium geometries that are consistent with predictions based on surface energies and interfacial tensions and the volume fractions of the two immiscible phases. In the limit of low organic volume fraction, the stimulated Raman scattering signature is consistent with the formation of a thin film or lens of the organic component on the surface of an aqueous droplet. By comparing the nonlinear spectroscopic signature with Mie scattering predictions for a core-shell structure, the thickness of the organic layer can be estimated with nanometer accuracy. Time-dependent measurements allow the evolving partitioning of the volatile organic component between the condensed and vapor phases to be investigated.     

Synthesis of inorganic-organic hybrids by incorporation of inorganic components into organic polymer using metal alkoxides

Inorganic-organic hybrids have been synthesized by incorporation of the inorganic component of Ti(OC₂H₅)₄ into the organic polymer of ethyl cellulose. The inorganic-organic hybrids did not dissolve in toluene used as a solvent for the starting materials. The ethanol was formed as a by-product of the alcoholysis condensation reaction between Ti(OC₂H₅)₄ and ethyl cellulose. These results suggest that ethoxy groups of Ti(OC₂H₅)₄ react with hydroxy groups of ethyl cellulose to form cross-linking bonds of –O–Ti–O–. The reaction of Ti(OC₂H₅)₄ with ethyl cellulose was further investigated by Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectroscopic experiments revealed that the Ti–O bond state of Ti(OC₂H₅)₄ was changed by refluxing a toluene solution of Ti(OC₂H₅)₄ with ethyl cellulose. The inorganic-organic hybrids have an interesting dielectric property; their dielectric constant is higher than that of ethyl cellulose and that of a simple mixture of TiO₂ and ethyl cellulose.     

Synthesis and application of inorganic/organic composite materials

A new type of inorganic-organic composite has been developed using organic monomeric or polymerizable silanes (with appropriate organic groupings like double bonds or epoxides) as monomers or in situ prepared or separately added nano-scale ceramic or metal particles. Due to the small size of the particulate phase, these composites are still highly transparent but show properties at least partially to be attributed to the inorganic phase. The introduction of special functions into these materials has been used for the fabrication of interesting functions like non-linear optical properties, low surface free energy coatings, controlled release properties or special mechanical properties (scratch resistance).