Novel organic–inorganic hybrid materials from renewable resources: Hydrosilylation of fatty acid derivatives

Novel hybrid organic–inorganic materials were prepared from 10‐undecenoyl triglyceride and methyl 3,4,5‐tris(10‐undecenoyloxy)benzoate via hydrosilylation. 1,4‐Bis(dimethylsilyl)benzene, tetrakis(dimethylsilyloxy)silane, and 2,4,6,8‐tetramethylcyclotetrasiloxane were used as crosslinkers. The hydrosilylation reaction was catalyzed by Karstedt's catalyst [Pt(0)–divinyltetramethyldisiloxane complex]. The networks were structurally characterized by Fourier transform infrared spectroscopy, ¹³C NMR, and ²⁹Si magic‐angle‐spinning NMR. The thermal properties of these hybrids were studied with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The obtained materials showed good transparency and promising properties for optical applications. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6295–6307, 2005     

Design of In Vitro Bioactive Hybrid Materials from the First Generation of Amine Dendrimers as Nanobuilding Blocks

In this work, the first generation of poly(propyleneimine) dendrimers were functionalized with alkoxysilane terminal groups and subjected to one of two different sol–gel process that followed two different catalytic pathways, that is base‐ or acid‐catalyzed pathways. Thus, two series of new organic–inorganic hybrid materials were obtained in the form of monolithic pieces with differences in terms of both morphology and silanol content, which originated from the different sol–gel pathway that was followed. Moreover, calcium ions were added into the hybrid composition to promote in vitro bioactivity and phosphorous sources were used during the sol–gel step to obtain an earlier bioactive response. Characterization of these organic–inorganic hybrid materials was performed by means of thermogravimetric and elemental analyses, Fourier transform infrared spectroscopy (FTIR), solid state ¹³C, ²⁹Si and ³¹P magic‐angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, N₂‐adsorption isotherms, mercury‐intrusion porosimetry, and ζ‐potential measurements. The in vitro bioactivity of the dendritic hybrid networks was evaluated by soaking the materials in simulated body fluid and the results were explained in terms of the composition of the hybrids and the sol–gel route that was followed to prepare them.     

Synthesis and characterization of organic–inorganic hybrid block copolymers containing a fully condensed ladder‐like polyphenylsilsesquioxane

A series of inorganic–organic hybrid block copolymers were synthesized via atom transfer radical polymerization using a fully condensed, ladder‐like structured polyphenylsilsesquioxane end‐functionalized macroinitiator. The inorganic portion, ladder‐like polyphenylsilsesquioxane, was synthesized in a one‐batch, base‐catalyzed system, whereas organic hard and soft monomers, styrene, and n‐butyl acrylate, were polymerized and copolymerized on the ends of the linear, inorganic backbone. Synthesized hybrid diblock, triblock, and random copolymers were characterized by ¹H NMR, ²⁹Si NMR, gel permeation chromatography, static light scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Hybrid block copolymers were well‐defined with low polydispersity (<1.4) and exhibited enhanced thermal properties in the form of increased glass transition and degradation onset temperatures over their organic analogues.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Reversible Light‐Driven Polymerization of Polyoxometalate Tethered with Coumarin Molecules

A new photosensitive polyoxometalate (POM) organic–inorganic hybrid compound has been prepared by covalently tethering coumarin moieties onto a Mn–Anderson cluster. This compound has been fully characterized by ¹H NMR, ¹³C NMR, FTIR, and UV/Vis spectroscopy, and ESI‐MS. This organic–inorganic hybrid compound can undergo reversible light‐driven polymerization and this process has been characterized in detail.     

Organic–inorganic hybrid networks by the sol–gel process and subsequent photopolymerization

Organic–inorganic hybrid materials were prepared by a convenient two‐step curing procedure based on sol–gel condensation and subsequent photopolymerization. Novel bismethacrylate‐based hybrid monomers with pendant, condensable alkoxysilane groups were prepared by Michael addition and possessed number‐average molecular weights between 580 and 1600 g/mol. The formation of inorganic networks by sol–gel condensation of the alkoxysilane groups in the presence of aqueous methacrylic acid was monitored with rheological measurements. The condensation conversion was monitored with solid‐state ²⁹Si cross‐polarization/magic‐angle spinning NMR spectroscopy. Subsequent photopolymerization led to organic–inorganic hybrid networks and low volume shrinkage, ranging from 4.2 to 8.3%, depending on the molecular weight of the hybrid monomer applied. Highly filled composite materials with glass filler fractions greater than 75% showed attractive mechanical properties with Young's moduli of 2700–6200 MPa. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4274–4282, 2001     

Preparation and properties of organic–inorganic hybrid gel films based on polyvinylpolysilsesquioxane synthesized from trimethoxy(vinyl)silane

Polyvinylpolysilsesquioxane (PVPS) organic–inorganic hybrid gel films comprising polyethylene and siloxane backbone linkages were prepared through two routes: trimethoxy(vinyl)silane (VTS) was first subjected to radical polymerization of the vinyl groups, followed by acid‐catalyzed hydrolytic polycondensation of the trimethoxysilyl groups (route A) to afford PVPS; in the second route PVPS was prepared in reverse order (route B). PVPS gel films were transparent and homogeneous. We find that the mechanical and heat‐resisting properties correlate both to the degree of polymerization and the degree of cross‐linking. Copyright © 2003 John Wiley & Sons, Ltd.     

Conductivity and characterization of polyurea electrolytes with carboxylic acid

Polyurea, which was synthesized from 4,4′‐diphenylmethane diisocyanate, Jeffamine‐ED2001 (weight‐average molecular weight: 2000), and 3,5‐diaminobanzoic acid (DABA) were doped with lithium perchlorate (LiClO₄) as the polyelectrolyte. Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and ⁷Li magic‐angle spinning (MAS) solid‐state NMR were used to monitor changes in the morphology of polyurea electrolytes corresponding to the concentration of LiClO₄ dopants. DSC showed the glass‐transition temperature of the hard and soft segments increases with salt concentration. FTIR indicated the carboxylic group of DABA coordinates with the Li⁺ ion, and the ordered hydrogen‐bonded urea carbonyl groups are destroyed when the salt concentration exceeds 0.5 mmole of LiClO₄ (gPUrea)^?1. The ⁷Li MAS solid‐state NMR investigation of the polyurea electrolytes revealed the presence of two Li⁺ environments at lower temperature. Impedance spectroscopy measurements showed that the conductivity behavior followed the Arrhenius equation, and the maximum conductivity occurred when the crystalline structure of polyurea was disrupted. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 4007–4016, 2003     

Proton transportation in an organic–inorganic hybrid polymer electrolyte based on a polysiloxane/poly(allylamine) network

A new class of proton‐conducting polymer was developed via the sol–gel process from amino‐containing organic–inorganic hybrids by the treatment of poly(allylamine) with 3‐glycidoxypropyltrimethoxysilane doped with ortho‐phosphoric acid. The polymer matrix contains many hydrophilic sites and consists of a double‐crosslinked framework of polysiloxane and amine/epoxide. Differential scanning calorimetry results suggest that hydrogen bonding or electrostatic forces are present between H₃PO₄ and the amine nitrogen, resulting in an increase in the glass‐transition temperature of the poly(allylamine) chain with an increasing P/N ratio. The ³¹P magic‐angle spinning NMR spectra indicate that three types of phosphate species are involved in the proton conduction, and the motional freedom of H₃PO₄ is increased with increasing P/N ratios. The conductivity above 80 °C does not drop off but increases instead. Under a dry atmosphere, a high conductivity of 10^?3 S/cm at temperatures up to 130 °C has been achieved. The maximum activation energy obtained at P/N = 0.5 suggests that a transition of proton‐conducting behavior exits between Grotthus‐ and vehicle‐type mechanisms. The dependence of conductivity on relative humidity (RH) above 50% is smaller for H₃PO₄‐doped membranes compared with H₃PO₄‐free ones. These hybrid polymers have characteristics of low water content (23 wt %) and high conductivity (10^?2 S/cm at 95% RH), making them promising candidates as electrolytes for fuel cells. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3359–3367, 2005     

Formation of a crosslinked POSS network by an unusual hydrosilylation: Thermo‐oxidative stabilization of the α‐cristobalite phase in its amorphous regions

A semicrystalline inorganic–organic hybrid crosslinked network containing polyhedral oligomeric silsesquioxane (POSS) cores was constructed by the unusual hydrosilylation of the terminal vinyl groups of an internal acetylene‐containing silane linker by a POSS monomer. Products from the thermal treatments of this network in either argon or air at 250, 550, and 1000 °C, respectively, were characterized by Fourier transform infrared, Solid‐state ¹³C and ²⁹Si magic angle spinning NMR, X‐ray diffraction and XPS analyses. The highly symmetrically functionalized POSS silica clusters, in the fluorite silica phase, in the network were found to remain unchanged on thermal treatment possibly due to the shielding of the silica core by the functionalities and a cancellation of thermal stresses on the silica core. Stabilization of the metastable α‐cristobalite phase, which is typically formed on cooling by a β‐ to α‐transition of the β‐cristobalite phase formed above 1400 °C, was observed in the amorphous regions in the network sample treated only to 1000 °C in air. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Catalytic Effects of Aluminum Butoxyethoxide in Sol-Gel Hybrid Hard Coatings

Hybrid inorganic-organic hard coatings on PMMA substrate were obtained by sol-gel reaction of 3-glycidoxypropyltrimethoxysilane(GPTS), tetramethyl orthosilicate(TMOS) and aluminum butoxyethoxide (Al(OEtOBu)₃). The catalytic effect of aluminum butoxyethoxide on inorganic condensation and epoxide polymerization has been studied by ¹³C, ²⁹Si nuclear magnetic resonance spectroscopy and by Fourier transformed infrared spectroscopy. Hardness of hybrid inorganic-organic materials were measured by nanoindentor and mainly influenced by the extent of epoxide polymerization and inorganic condensation of their coating catalyzed by aluminum butoxyethoxide.     

Diol‐Linked Microporous Networks of Cubic Siloxane Cages

A new class of inorganic–organic hybrid porous materials has been synthesized by a reaction between octa(hydridosilsesquioxane) (H₈Si₈O₁₂), which has a double‐four‐ring (D4R) structure, and various diols, such as 1,3‐propanediol (PD), 1,4‐cyclohexanediol (CHD), and 1,3‐adamantanediol (AD). Solid‐state ²⁹Si magic‐angle‐spinning NMR spectroscopic analysis confirmed that most of the corner Si? H groups reacted with diols to form Si‐O‐C bonds with retention of the D4R cage. Nitrogen adsorption–desorption studies showed that the products are microporous solids with high BET surface areas (up to ≈580 m² g^?1 for CHD‐ and AD‐linked products). If n‐alkanediols are used as linkers, the surface area becomes smaller as the number of carbon atoms is increased. The thermal and hydrolytic stability of the products strongly depend on the type of diol linkers. The highest stabilities are found for the AD‐linked products, which are thermally stable up to around 400 °C and remain intact even after being soaked in water for 1 day. In contrast, the PD‐linked product is easily hydrolyzed in water to give microporous silica. These results offer a new route toward a series of silica‐based porous materials with unique structures and properties.     

In situ Alkylation of 4,4′‐Vinylenedipyridine for Inorganic‐Organic Iodides/Iodidomercurates

Solvothermal reactions of HgI₂, 4,4′‐vinylenedipyridine, and HI in alcoholic solution (methanol, ethanol, or pentanol) gave rise to a family of organic‐inorganic hybrid complexes, formulated as [C₁₄H₁₆N₂][I₄]^2– ( 1 ), [C₁₆H₂₀N₂][HgI₄] ( 2 ), and [C₂₂H₃₂N₂][HgI₄]₄ ( 3 ). Single‐crystal X‐ray diffraction reveals that all three compounds are discrete structures, including the inorganic anion [I₄]^2– or [HgI₄]^2– and an organic cation, where the resulting organic cations were generated in situ alkylation reactions of 4,4′‐vinylenedipyridine with alcohols, with cleavage of the alcoholic C–O bond followed by a one‐step in situ N‐alkylation reaction of 4,4′‐vinylenedipyridine in acidic HI solution. X‐ray powder diffraction (XRD), ¹H NMR and ¹³C NMR, energy‐dispersive X‐ray (EDS), IR, as well as UV/Vis/NIR spectroscopy, elemental analysis, and thermogravimetric analysis (TGA) were used to characterize the complexes.     

An expedient ‘click’ approach for the synthetic evaluation of ester‐triazole‐tethered organosilica conjugates

The present work articulates the synthesis of a new series of organo‐functionalized triethoxysilanes derived from versatile carboxylic acids and 3‐azidopropyltriethoxysilane in excellent yields. A proficient and convenient route implicating the Cu(I)‐catalysed 1,3‐cycloaddition of organic azide with terminal alkynes, labelled as click silylation, has been developed for the generation of ester‐triazole‐linked alkoxysilanyl scaffolds ( 4a – f ). All the synthesized compounds have been thoroughly characterized using elemental analysis and Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopic techniques. Importantly, the fabricated alkoxysilanes are potentially amenable for an in situ sol–gel condensation reaction with silica nanospheres leading to the incorporation of organic functionality via covalent grafting onto the nanostructured particle system. As a proof of concept, a one‐pot preparation of organic–inorganic hybrid nanoparticles is presented using bis‐silane 4 f . The efficiency and selectivity of the prepared nanocomposite towards metal ions is highlighted using adsorption experiments, and the immobilized nanoparticles present a high sensing efficiency towards Cu²⁺ and Pb²⁺ ions while demonstrating better response than that of the bulk material.     

Synthesis,characterization, and proton‐conducting properties of organic–inorganic hybrid membranes based on polysiloxane zwitterionomer

The synthesis and characterization of a series of zwitterionic hybrid membranes based on a zwitterionic siloxane precursor (ZS) are described. Flexible, transparent, optically homogeneous films were prepared. With the further incorporation of poly(ethylene glycol) (PEG), the hybrid films became more flexible but translucent. The structure of the inorganic sides was probed with solid‐state ²⁹Si NMR spectroscopy, and the organic sides and the chemical process involved were characterized with solid‐state ¹³C cross‐polarization/magic‐angle spinning NMR. A higher content of ZS led to higher proton conductivity of the hybrid electrolytes. Moreover, the proton conductivity was enhanced by the addition of the plasticizing component of PEG to the hybrid matrix; this was ascribed to the increased water uptake and free volume of the hybrid matrix and the dissociation of sulfonic acid groups. The proton conductivity of these hybrid membranes could be increased up to 3.5 × 10^?2 S/cm by the temperature and relative humidity being increased to 85 °C and 95%, respectively. The proton‐conduction behavior of these hybrid membranes is also briefly discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3444–3453, 2006     

Inorganic–Organic Heteropolyacid–Gold(I) Hybrids: Structures and Catalytic Applications

Gold(I)‐polyoxometalate hybrid complexes 1 – 4 ([PPh₃AuMeCN]_xH_4?xSiW₁₂O₄₀, x=1–4) were synthesized and characterized. The structure of the primary gold(I)–polyoxometalate 1 (x=1) was fully ascertained by XRD, FTIR, ³¹P and ²⁹Si magic‐angle spinning (MAS) NMR, mass spectroscopy, and SEM–energy dispersive X‐ray spectroscopy (EDX) techniques. Moreover, this complex exhibited better catalytic activity and selectivity compared with standard, homogeneous, gold catalysts in the new rearrangement of propargylic gem‐diesters.     

X‐ray Diffraction and Solid‐State NMR Studies of a Germanium Binuclear Complex

A compound formulated as (C₄H₁₂N₂)[Ge₂(pmida)₂(OH)₂] ? 4 H₂O (where pmida^4?=N‐(phosphonomethyl)iminodiacetate and C₄H₁₂N₂²⁺=piperazinedium cation), containing the anionic [Ge₂(pmida)₂(OH)₂]^2? complex, has been synthesised by the hydrothermal approach and its structure determined by single‐crystal X‐ray diffraction analysis. Several high‐resolution solid‐state magic‐angle spinning (MAS) NMR techniques, in particular two‐dimensional ¹H–X(¹³C,³¹P) heteronuclear correlation (HETCOR) and ¹H–¹H homonuclear correlation (HOMCOR) experiments incorporating a frequency‐switched Lee–Goldburg (FS‐LG) decoupling scheme, have been employed for the first time in such a material. Using these tools in tandem affords an excellent general approach to study the structure of other inorganic–organic hybrids. We assigned the NMR resonances with the help of C ??? H and P ??? H internuclear distances obtained through systematic statistical analyses of the crystallographic data. The compound was further characterised by powder X‐ray diffraction techniques, IR and Raman spectroscopy, and by elemental and thermal analyses (thermogravimetric analysis and differential scanning calorimetry).     

Unusual inorganic phase formation in ultraviolet‐curable organic–inorganic hybrid films

Inorganic–organic hybrid materials were prepared with a cycloaliphatic epoxide adduct of linseed oil with tetraethylorthosilicate (TEOS) oligomers via a cationic UV‐curing process. The TEOS oligomers were prepared in the presence of water and ethanol with hydrochloric acid as a catalyst. The TEOS oligomers were characterized with ¹H and ²⁹Si NMR and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Hybrid films were cured, and the dynamic mechanical and thermal properties of the hybrid films were evaluated as a function of the TEOS oligomer content. The morphology of the hybrid films was examined with atomic force microscopy, transmission electron microscopy, and small‐angle light scattering. The microscopy and dynamic mechanical data indicated that the hybrid films were heterogeneous materials with various inorganic particle sizes dispersed within the organic matrix. In addition, ²⁹Si solid‐state NMR spectroscopy was used to investigate the coupling between the silicate region and organic regions. A schematic model is proposed to address structural features of hybrid materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1607–1623, 2005     

Effect of the synthetic method and support porosity on the structure and performance of silica‐supported CuBr/pyridylmethanimine atom transfer radical polymerization catalysts. I. Catalyst preparation and characterization

Silica‐supported CuBr/pyridylmethanimine (PMI) complexes that facilitate the atom transfer radical polymerization of methyl methacrylate have been prepared and characterized. Four different synthetic routes, including multistep‐grafting (M1), two‐step‐grafting (M2), one‐pot (M3), and preassembled‐complex (M4) methods, have been evaluated on three different silica supports (mesoporous SBA15 with 48‐ and 100‐Å pores and nonporous Cab‐O‐Sil EH5). The resulting solids have been characterized by a battery of techniques, including thermogravimetric analysis/differential scanning calorimetry, FT‐Raman spectroscopy, ¹³C and ²⁹Si magic‐angle‐spinning and cross‐polarity/magic‐angle‐spinning spectroscopy, low‐temperature nitrogen physisorption, and elemental analysis. The combination of elemental analysis and spectroscopic results has indicated that a variety of different surface species likely exist for most catalysts, including copper species that are both monocoordinated and biscoordinated by PMI ligands, and PMI‐free copper bromide species interacting with the silica surface. M4 appears to give a material that has the smallest amount of the uncomplexed ligand (by FT‐Raman spectroscopy) and is, therefore, the most homogeneous. After M4, the metallation efficiency decreases in the order M2 ≥ M3 > M1, with M1 giving a material with a highly heterogeneous surface composition. The ligand loading on all the catalysts has been determined to be approximately 1 mmol/g of SiO₂, with Cab‐O‐Sil‐supported materials giving much higher ligand densities because of its lower surface area. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1367–1383, 2004     

Preparation and characterization of novel negatively charged hybrid membranes

Charged hybrid membranes with anionic‐ or cationic‐exchange groups have attracted increasing interest due to their higher thermal stabilities and structural flexibilities which are considered suitable for use in some harsh conditions, such as higher temperature and strongly oxidizing circumstances, for industrial applications. To develop new routes to synthesize the negatively charged hybrid membranes, a series of hybrid membranes were prepared via free radical polymerization of glycidylmethacrylate (GMA) and γ‐methacryloxypropyl trimethoxy silane (MPTMS) monomers, and ring‐opening of epoxide to create negatively charged ? SO₃H groups in the polymer chains. The fundamental properties of these prepared membranes were characterized through TGA, ion‐change capacity (IEC), and MALDI–TOF mass spectra. TGA showed that the thermal degradation temperature of these membranes could reach up to 300°C and the temperature of the first endothermic peak decreased with an increase in the content of ? SO₃H groups. IEC measurements showed that their IECs were within the range of 0.22–0.35 mmol g^?1. MALDI–TOF spectrometry indicated that the incorporation of GMA into the hybrid matrix could improve the structural stability of the membranes. These findings demonstrated that the ion‐exchange properties and structural stability of negatively charged hybrid membranes can be conveniently controlled by adjusting the GMA moiety in the hybrid matrix. Copyright © 2009 John Wiley & Sons, Ltd.     

Practical Synthesis of [n]Cycloparaphenylenes (n=5, 7–12) by H2SnCl4‐Mediated Aromatization of 1,4‐Dihydroxycyclo‐2,5‐diene Precursors

Cyclic precursors of cycloparaphenylenes (CPPs) containing 1,4‐dihydroxy‐2,5‐cyclohexadien‐1,4‐diyl units are prepared by modifying a synthetic method developed by Jasti and co‐workers for the synthesis of corresponding 1,4‐dimethoxy derivatives. Reductive aromatization of the diyl moieties by SnCl₂/2 HCl takes place under mild conditions and affords the CPPs in good yields, incorporating 5 or 7–12 phenylene units. Highly strained [5]CPP is synthesized in greater than 0.3 g scale. ¹¹⁹Sn NMR spectroscopy clarifies the in situ formation of an ate complex, H₂SnCl₄, upon mixing a 2:1 ratio of HCl and SnCl₂, which serves as a highly active reducing agent under nearly neutral conditions. When more than 2 equivalents of HCl, in relation to SnCl₂, are used, acid‐catalyzed decomposition of the CPP precursors takes place. The stoichiometry of HCl and SnCl₂ is critical in achieving the desired aromatization reaction of highly strained CPP precursors.