Materials Literature
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Viscosity tuning of preceramic polymers, in order to adapt them to various applications, has been elaborated by the authors. Thermal and photochemical crosslinking adjusts the viscosity of the polyureasilazane Ceraset in the range from 0.05 up to 20 Pas; the low viscous Ceraset can be used for the reaction molding of…
We studied the crystallization behavior in a diblock copolymer/homopolymer blend system exhibiting “dry-brush” phase behavior in the melt. A nearly symmetric poly(ethylene oxide)- block -polybutadiene (PEO- b -PB) was blended with a PB homopolymer (h-PB) having approximately the same molecular weight as that of the PB…
The structural stability of mesoporous molecular sieves organically functionalized by a direct method has been investigated in terms of the stability against moisture treatment and mechanical pressure. Incorporation of organic groups directly attached to Si atoms by the use of organosilanes results in an enhancement o…
Abstract Environmental factors such as oxygen, temperature, and microbial species may have significant effects on decomposition of biodegradable polymers. A representative biodegradable, thermoplastic polymer, poly(3‐hydroxybutyrate‐ co ‐hydroxyvalerate) (PHBV), was decomposed in an aqueous medium under controlled lab…
Summary The surface chemistry of Eucalyptus grandis wood pulp fibres was investigated using the sessile drop apparent contact angle, XPS and TOF-SIMS techniques. Pulp fibres were studied using different chemical pulping conditions. The pulping affected the surface coverage of lignin and extractives, as indicated by XP…
Experiments designed to mimic cell receptor structures on biomaterial surfaces showed that slow evaporation of water-based suspensions containing polystyrene nanospheres created translucent nanostructured films enclosed by highly regular ring shaped patterns. Our finding represents a novel method to functionalize biom…
Covalently cross-linked, three-dimensional nanodomained networks were prepared from radially layered poly(amidoamine−organosilicon) (PAMAMOS) copolymeric dendrimers containing hydrophilic polyamidoamine (PAMAM) interiors and reactive hydrophobic organosilicon (OS) exteriors. Two different types of curing chemistries w…
The dynamics of photoinduced formation of electron and hole centers at the surface of MgO powder has been investigated in situ using EPR spectroscopy. Monochromatic excitation of the sample with 282 nm photons leads to creation of well-separated electron and hole centers at the surface. Polychromatic (200−900 nm) irra…
Reaction of M(OAc)(2).xH(2)O (M = Mn, Cu, or Cd) with di-tert-butyl phosphate (dtbp-H) in a 1:2 molar ratio in methanol followed by slow crystallization of the resultant solid in MeOH/THF medium results in the formation of three new polymeric metal phosphates [M(dtbp)(2)](n)() [M = Mn, 1 (beige); M = Cu, 2 (blue)] and…
Encapsulation of chiral ruthenium porphyrin [RuII(D4-Por*)CO] in modified mesoporous silica supports such as MCM-41 and MCM-48 achieves active catalysts for asymmetric epoxidation of alkenes by 2,6-dichloropyridine N-oxide and intramolecular cyclopropanation, which is the first example of chiral metalloporphyrin suppo…
The novel nickel-substituted, dimeric phosphotungstate [Ni(3)Na(H(2)O)(2)(PW(9)O(34))(2)](11-) (1) has been synthesized and characterized by IR spectroscopy, elemental analysis, and electrochemistry. X-ray single-crystal analysis was carried out on Na(11)[Ni(3)Na(H(2)O)(2)(PW(9)O(34))(2)].21.25H(2)O, which crystallize…
Gold nanoparticles supported on highly hydrophobic ethane bridged Ti incorporated mesoporous organosilica are reported for enhanced vapor phase epoxidation of propene using H2 and O2.
Tungstophosphoric acid (H3PW12O40) effectively activates hexamethyldisilazane for the selective silylation of primary, secondary, tertiary and phenolic hydroxy groups under solvent-free conditions at 55–60 °C.
Si and SiC filler loaded silane/polysiloxane slurries were used for the fabrication of ceramic tapes in the Si-O-C-(N) system. Single and multilayer tapes, as well as light weight structures, were fabricated by the doctor blade process. Increasing the Si to SiC filler ratio led to higher porosities in case of pyrolysi…
Abstract The influence of Joule heating treatments and carbon black (CB) on the electrical and thermal behavior of epoxy resin composites is well described in this article. The effect of CB and Joule heating on network structure characteristics, such as shrinkability, interparticle distance between conductive particle…
Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepared by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size a…
This paper describes large thick flattened multiwalled carbon nanotubes (MWCTs) that have been synthesized using the precursors Co(CO) 3 NO or Fe(CO) 5 . TEM and HRTEM clearly show that even thick MWCNTs (more than 30 layers) can be collapsed or partially flattened. The transition from circular to flattened was observ…
The stability and electronic structure of a single monatomic Al wire has been studied using the ab initio pseudopotential method. The Al wire undergoes two structural rearrangements under compression, i.e., zigzag configurations at angles of $140^o$ and $60^o$. The evolution of electronic structures of the Al chain as…
The crystallization and subsequent polymorphic transformation from the β to the α form of glycine has been studied using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. The crystal structure and morphology of β glycine have been determined, and the influence of solvent, s…
Based on the generalized valence bond picture, a Schwinger boson mean field theory is applied to the symmetric SU(4) spin-orbital systems. For a two-leg SU(4) ladder, the ground state is a spin-orbital liquid with a finite energy gap, in good agreement with recent numerical calculations. In two-dimensional square and…