Octavinylsilsesquioxane Research Articles

A facile route to multifunctional cage silsesquioxanes via the photochemical thiol–ene reaction

Starting from octavinylsilsesquioxane (OVS), several multifunctional cage silsesquioxanes were successfully prepared by the photo–induced thiol–ene reaction with the corresponding commercially available thiols. These cage compounds were fully characterized by FTIR, NMR, ESI–MS and element analysis.

Preparation and characterization of a PVDF/EG-POSS hybrid ultrafiltration membrane for anti-fouling improvement

The octa vinyl silsesquioxane (OvPOSS) was used to synthesis POSS grafted ethylene glycol (EG) (EG-POSS). The hydrophilicity and anitifouling property of pure PVDF membrane was improved by incorporating EG-POSS in PVDF membrane.

Synthesis and Characterization of a POSS-PEG Macromonomer and POSS-PEG-PLA Hydrogels for Periodontal Applications

A novel water-soluble macromonomer based on octavinyl silsesquioxane has been synthesized and contains vinyl-terminated PEG 400 in each of the eight arms to promote water solubility. The macromonomer was characterized by NMR and FTIR and its aqueous solution properties examined. In water it exhibits an LCST with a cloud point at 23 °C for a 10 wt % aqueous solution. It is surface active with a CMC of 1.5 × 10(-5) M in water and in 20:80 v/v acetone/water the CMC is 7.1 × 10(-5) M, and TEM images showed spherical 22 nm aggregates in aqueous solution above the CMC. The macromonomer was copolymerized in a 20:80 v/v acetone/water mixture with a vinyl-terminated, triblock copolymer of lactide-PEG-lactide to form a library of cross-linked hydrogels that were designed for use as scaffolds for alveolar bone repair. The cross-linked copolymer networks were shown to contain a range of nm-μm sized pores and their swelling properties in water and PBS at pH 7.4 were examined. At pH 7.4 the hydrogel networks undergo a slow hydrolysis with the release of principally PEG and lactic acid fragments. The hydrogels were shown to be noncytotoxic toward fibroblast cultures at pH 7.4, both initially (days 1-5) and after significant hydrolysis had taken place (days 23-28).

Synthesis of hybrid dendritic molecules with diazaphospholidine oxide grafted at the surface of octavinylsilsesquioxane (OVS)

A range of dendritic molecules was made using the monodentate SEMI-ESPHOS phosphine oxide ligand, which was derivatised with a series of functional groups including bromide, vinyl, allyl and terminal alkyne. Several methods to attach the resulting precursors onto octavinylsilsesquioxane (OVS), ranging from hydrosilylation, Suzuki, Heck, Grubbs or Sonogashira coupling reactions, have been investigated. Cross-metathesis of SEMI-ESPHOS oxide dendrons containing vinyl end groups with OVS catalyzed by Grubbs' catalyst was proven to be effective in the formation of precursors for dendritic molecules based on OVS.

Silsesquioxane‐based nanocomposite dendrimers with photo‐luminescent and charge transport properties

The synthesis and characterization of octavinylsilsesquioxane (OVS)-based nanocomposite dendrimers with luminescent and charge transport properties are reported. The nanocomposite dendrimers were prepared in high yield using mild Heck chemistry of mono-haloaromatic compounds with the peripheral vinylsilane groups of OVS. Attachment of 2-naphthalene, 2-(9,9-dimethyl)fluorene, and 2-(4-phenyl)-5-(1-naphthyl)-1,3,4-oxadiazole resulted in materials with blue-violet emission (360-380 nm) and photo-luminescent quantum efficiencies (PLQEs) from 1 to 26%. Blue-green emission was observed for attachment of 1-pyrene, 9-anthracene, and N1-(4-phenyl)-N1,N4,N4-triphenylbenzene-1,4-diamine with PLQEs ranging from 23 to 50%. Despite the planar characteristics of the organic dendrons, the nanocomposite dendrimers are completely amorphous and have high glass transition temperatures (Tg) ranging from 115 to 186 degrees C with decomposition temperatures (Td) exceeding 450 degrees C. Matrix-assisted laser desorption ionization-time of flight shows that unlike traditional Heck chemistry, haloaromatic compounds are adding twice across the vinylsilane groups. Finally, organic light emitting diodes using the aromatic amine-based dendrimer as hole injection layers show 55% improvement in device efficiency over traditional materials (5.16 vs. 3.24 cd A(-1)) with brightness levels exceeding 40,000 cd m(-2).

Disorder of the sublattice of terminal groups and phase transition in octa (vinylsilsesquioxane)

Octa(vinylsilsesquioxane) is one of the members of a series of materials which are important for microelectronics, viz., the organylsilsesquioxanes with the general formula (RSiO/sub 1.5/)/sub n/, where R is an organic substituent, and exists in the form of a molecular crystal consisting of (C2H3SiO/sub 1.5)9 molecules. The almost cubic silicon-oxygen skeleton is slightly extended along the C3 axis. According to the data from x-ray diffraction analysis, at room temperature there is disordering of the terminal C/sub US / carbon atoms of the substituent in the compound: among three positions for substituents lying on the third-order axis and among two positions for those in positions which are not symmetry centers. However, the question of the nature of the disordering (whether it is static or dynamic) remained open. In the present work the authors used the method of proton NMR (PMR), NMR relaxation, and precision calorimetry to establish that dynamic disordering appears in octa(vinylsilsesquioxane) at T = 230K in the sublattice of the terminal groups of atoms and that it is accompanied by a phase transition in the system.