Unusual properties

In addition to tire standard model systems described above, more exotic particles have been prepared witli certain unusual properties, of which we will mention a few. For instance, using seeded growtli teclmiques, particles have been developed witli a silica shell which surrounds a core of a different composition, such as particles witli magnetic [12], fluorescent [13] or gold cores [14]. Anotlier example is tliat of spheres of polytetrafluoroetliylene (PTFE), which are optically anisotropic because tire core is crystalline [15]. 

All Group IV elements form both a monoxide, MO, and a dioxide, MO2. The stability of the monoxide increases with atomic weight of the Group IV elements from silicon to lead, and lead(II) oxide, PbO, is the most stable oxide of lead. The monoxide becomes more basic as the atomic mass of the Group IV elements increases, but no oxide in this Group is truly basic and even lead(II) oxide is amphoteric. Carbon monoxide has unusual properties and emphasises the different properties of the group head element and its compounds. 

Pinacol possesses the unusual property of forming a crystalline hexahydrate, m.p. 45°, and the pinacol is separated in this form from the unreacted acetone and the tsopropyl alcohol. The magnciaium is conveniently amalgamated by dissolving mercuric chloride in a portion of the acetone mercury is then liberated by the reaction ... 

Polyamides from diamines and dibasic acids. The polyamides formed from abphatic diamines (ethylene- to decamethylene-diamine) and abphatic dibasic acids (oxabc to sebacic acid) possess the unusual property of forming strong fibres. By suitable treatment, the fibres may be obtained quite elastic and tough, and retain a high wet strength. These prpperties render them important from the commercial point of view polyamides of this type are cabed nylons The Nylon of commerce (a 66 Nylon, named after number of carbon atoms in the two components) is prepared by heating adipic acid and hexamethylenediamine in an autoclave ... 

Many of the unusual properties of the perfluorinated inert fluids are the result of the extremely low intermolecular interactions. This is manifested in, for example, the very low surface tensions of the perfluorinated materials (on the order of 9-19 mN jm. = dyn/cm) at 25°C which enables these Hquids to wet any surface including polytetrafluoroethene. Their refractive indexes are lower than those of any other organic Hquids, as are theh acoustic velocities. They have isothermal compressibilities almost twice as high as water. Densities range from 1.7 to 1.9 g/cm (l )-... 

Within the scope of the original definition, a very wide variety of ionomers can be obtained by the introduction of acidic groups at molar concentrations below 10% into the important addition polymer families, followed by partial neutralization with metal cations or amines. Extensive studies have been reported, and useful reviews of the polymers have appeared (3—8). Despite the broad scope of the field and the unusual property combinations obtainable, commercial exploitation has been confined mainly to the original family based on ethylene copolymers. The reasons for this situation have been discussed (9). Within certain industries, such as flexible packaging, the word ionomer is understood to mean a copolymer of ethylene with methacrylic or acryhc acid, partly neutralized with sodium or zinc. 

Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

The unusual properties of xanthan undoubtedly result from its stmctural rigidity, which in turn is a consequence of its Linear, ceUulosic backbone that is stiffened and shielded by the trisaccharide side chains. The conformation of xanthan in solution is a matter of debate. It does appear that the conformation changes with conditions. 

This journal issue features the many unusual properties of carbon nanotubes. Most of these unusual properties are a direct consequence of their ID quantum behavior and symmetry properties, including their unique conduction propertiesjll] and their unique vibrational spectra[8]. 

These unusual properties of fluorocarbons reflect theu nonpolar character, low polarizability, and overall relatively weak intermolecular attractions Saturated perfluoro-terr-ammes and -dialkyl ethers also closely resemble fluorocarbons rather than typical amines or ethers in their physical properties [4,... 

Osmium makes a sluggish carbonyl hydrogenation catalyst but has the unusual property of reducing a, -unsaturated aldehydes to the unsaturated alcohol in good yield (85). The system has proved erratic high selectivity can only be obtained through prereduction of the catalyst just before use. 

Atwood, J. L., Atwood, J. D., Inorganic Compounds with Unusual Properties, Advances in Chemistry Series No. 

Water has many unusual properties in addition to its high boiling point. As pointed out in Chapter 8, it has a very high specific heat, 4.18 J/g °C. Its heat of vaporization per gram, 2.26 kj/g, is the highest of all molecular substances. Both of these properties reflect the hydrogen-bonded structure of the liquid. Many of these bonds have to be broken when the liquid is heated all of them disappear on boiling. 

The rapid development of macromoiecular chemistry has recently brought to light a number of most interesting problems related to the synthesis of polymers with unusual properties. The chemistry of polyconjugated systems undoubtedly occupies a leading place among these problems. 

G.L. Wilkes, Synthesis of Novel Polymers with Unusual Properties by Radical Polymerization , USARO Rept, Contract DA-ARO-D-31-124-73-G27, Princeton Univ, Princeton (1974)... 

The chemistry of plutonium is unique in the periodic table. This theme is exemplified throughout much of the research work that is described in this volume. Many of the properties of plutonium cannot be estimated accurately based on experiments with lighter elements, such as uranium and neptunium. Because massive amounts of plutonium have been and are being produced throughout the world, the need to define precisely its chemical and physical properties and to predict its chemical behavior under widely varying conditions will persist. In addition to these needs, there is an intrinsic fundamental interest in an element with so many unusual properties and with so many different oxidation states, each with its own chemistry. 

Because of its stability and unusual properties, the crystal growth of TiB2 is the most studied process of boride preparation by CVD. It is interesting from both a scientific and an engineering viewpoint, and because of the availability, low cost and... 

A protein, designated cyctochrome c", isolated from the methylotrophic bacterium Methylophilus methylotrophus, has been studied extensively because of its unusual properties and was found to have an average molecular mass of 14293.0 Da and to contain 124 amino acid residues. The A-terminal sequence to residue 62 had been determined and the heme binding site had been located at Cys-49 and Cys-52 [12]. Further studies were concerned with determining the remainder of the sequence. 

Some inorganic molecules containing metal-oxygen bonds have unusual properties (Scheme 11). In disiloxane, Si-O-Si angles between the single bonds are wider than those of ethers. The bond angle is 144.1° for HjSi-O-SiHj [127] and 111.5° for H3C-O-CH3 [128]. The Si-Si bond distance in the three-membered... 

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