Efficient preparation of 2-azulenylboronate and Miyaura-Suzuki cross-coupling reaction with aryl bromides for easy access to poly(2-azulenyl)benzenes

This paper describes an efficient preparation of 2-azulenylboronate (6) starting from 2-iodoazulene by halogen-metal exchange reaction using n-BuLi and subsequent quenching with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. The boronate 6 has been found to undergo Pd-catalyzed Miyaura-Suzuki cross-coupling reaction with a range of aryl bromides including aromatic poly bromides utilizing Pd₂(dba)₃-P(t-Bu)₃ as a catalyst and establishes a strategy to produce novel poly(2-azulenyl)benzenes, some of which are found to be insoluble in common organic solvents, however. The redox behavior of 2-arylazulenes and poly(2-azulenyl)benzenes was examined by cyclic voltammetry (CV) and compared with those of 6-azulenylbenzene derivatives reported previously.     

Perfluoropolyether-Silica Hybrids: Preparation and Surface Characterization

,-Triethoxysilane terminated perfluoropolyether-polycaprolactone block copolymers, TXCL(x)Si, were synthesised, characterised and subsequently reacted with tetraethoxysilane to prepare transparent organic-inorganic hybrid materials by using the sol–gel process. Surface characterization was carried out through contact angle measurements. All the materials investigated (independently on both the reaction time of the sol–gel reaction before coating application and the bulk organic-inorganic ratio) showed a strong hydrophobic character when compared with non-fluorinated and fully inorganic control materials. The highest water contact angles were obtained when TXCL(x)Si oligomer used for the preparation of the hybrid contained short hydrogenated polycaprolactone segments. In all cases, the surface tension values indicated that the very surface at the air-coating interface showed almost completely perfluoropolyether segments.     

Preparation and Optical Properties of Silica-Poly(ethylene oxide) Hybrid Materials

Structural evolution and optical properties of the silica-poly(ethylene oxide) hybrid films prepared from -glycidoxypropyltrimethoxysilane (GPTS) and 1-methylimidazol (MI) are studied. Polymerization of the epoxy groups is achieved by using 1-methylimidazol as a thermal curing agent. In liquid state ¹H &¹³ C NMR spectroscopy, it is found that silica condensation mainly occurs without epoxy ring opening. The epoxide polymerization is confirmed by using FT-IR, solid state CP-MAS ¹³C-NMR, and differential scanning calorimetry (DSC). The hybrid material is densified due to the epoxide polymerization as well as silica condensation with thermal curing. As a result, the thermal curing increases refractive index and extinction coefficient and shifts UV optical absorption edge to longer wavelength.     

Auto-Organisation in Silica-Based Organic-Inorganic Gels Obtained by Sol-Gel Process

A new type of hybrid material is prepared through sol-gel processing by the polycondensation of (MeO)₃Si–R–Si(OMe)₃ units containing a rigid organic anisotropic group R. The hybrid covalently bounded organic-inorganic gel shows an unexpected structural birefringence n (n = 2 × 10^–3). This birefringence is induced by a strain field anisotropy during gel aging as revealed by simultaneous dynamic light scattering and birefringence measurements. To better address the role of the strain field, we use a free interface sol-gel/air to control strain anisotropy and to measure the gel optical axis and its birefringence. We find that the birefringence is associated to a long-range orientational order of organic moieties induced by the strain anisotropy during the gel aging.     

Mesoporous hybrid organosilica containing urethane moieties

Mesoporous hybrid material containing urethane moieties in functionalized long chain organic group have been synthesized by using bis[3-(triethoxysilyl) propyl urethane]ethane (BTESPUE) and tetraethoxysilane as structural ingredients. The incorporation of BTESPUE within the framework of mesoporous material was confirmed by Fourier transform-infrared, X-ray photoelectron spectroscopy, solid-state NMR spectroscopy and thermogravimetric analysis. This material had a thick wall and uniform pore, which may be attributed to the hydrogen bonding inside framework due to urethane moieties.     

A FT-IR Study of the Synthesis of Boron Ormosils by Means of the Sol-Gel Process

Borosilicon ormosil materials can be prepared by using the sol-gel method. The precursors used for the synthesis were TEOS (tetraethylorthosilicate), TEB (triethylborate) and PDMS (silanol terminated polydimethylsiloxane). Four samples containing different boron amounts were prepared and reactions were studied by FT-IR spectroscopy. The spectra were deconvoluted and the time evolution of the most important bands was analysed in order to know the role of the boron in the reaction process. Different plots show that boron affects the self-condensation process of the hydrolysed TEOS molecules but does not have much influence in the way of the co-polymerization.     

Preparation and antibacterial activity of hybrid materials containing quaternary ammonium salts via sol-gel process

Organic-inorganic hybrid coatings containing quaternary ammonium salts (QAS) bonded to the organic-inorganic network were prepared from tetraethoxysilane and triethoxysilane terminated poly(ethylene glycol)-block-poly(ethylene) using a sol-gel process. They were applied as a thin layer (0.6-1 μm) to PE films and the antibacterial activity of the coated films was tested against both Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. Measurements at different contact times showed a rapid decrease of the viable count for both the tested strains. In particular, after 48 h of contact, a decrease of 96.4% and 99.1% of E. coli and S. aureus, respectively, was observed. The permanence of the antibacterial activity of the coated films was demonstrated through repeated washings and prolonged immersion in physiological saline solutions at 37 °C. Indeed, due to the removal of QAS moieties by the nucleophilic attack of water, the antibacterial activity after 24 h was strongly reduced when measured on samples submitted to several washings. However, a quite good antibacterial activity was observed even on the same samples after 96 h, probably due to a spontaneous partial restoring of the QAS on the surface. Very good transparency, quite good adhesion and high wettability are further features of these hybrid coatings.     

Hydrolysis and polycondensation of acid-catalyzed Phenyltriethoxysilane (PhTES)

The effects of acid catalyst, water content and reaction temperature on the hydrolysis and polycondensation of phenyltriethoxysilane (PhTES) were studied using ²⁹Si NMR spectroscopy. The sol catalyzed by hydrochloric acid showed the simultaneous progress of hydrolysis and polycondensation. In addition, the reaction rate was almost independent of reaction temperature. On the other hand, the polycondensation in the PhTES-derived sol mixed with an excess amount of water and acetic acid as a catalyst proceeded after completion of the hydrolysis. In the acetic acid-catalyzed system, the degree of the hydrolysis and polycondensation largely depends on the reaction temperature.     

Star Gels: New Hybrid Network Materials from Polyfunctional Single Component Precursors

New molecular precursors to inorganic/organic hybrid network materials have been designed and synthesized. The molecules comprise multiple trialkoxysilane-terminated arms linked to an organic core. When hydrolyzed, these materials form network structures whose network elements are interconnected with flexible crosslinks. Clear, compliant glasses and thick films have been generated from a number of these precursors. They are significantly tougher and less brittle than purely inorganic glasses or conventional purely organic thermosetting materials such as epoxy resins. The gels typically lose all surface-connected porosity during drying. Gelation rates for pure star gel precursors can be extremely high; the stars can also greatly enhance condensation rates for conventional sol-gel systems based on tetraalkoxysilanes.     

CONDUCTIVITY BEHAVIOR OF IONIC AI（OH）3-POLYACRYLAMIDE HYBRIDS IN AQUEOUS SOLUTIONS

The conductivity behavior of Al(OH)3-acrylamide hybrid polyacrylamide (hybrid PAAm) in distilled water was studied. A discontinuity phenomenon of the conductivity (k) versus concentration (c) curve of the hybrid PAAm in a certain concentration regime is found. This phenomenon is dependent on the molecular weight of the hybrid PAAm and on the particle size and content of the AI(OH)3 colloid in the hybrid PAAm. This phenomenon was accounted for assuming ionization of the hybrid PAAm.