Novel phase structure

Ti-UTD-8 Novel phase structure TEOT Fumed silica Cp 2CoOH Large pore molecular sieve, with one-dimensional channels 175 °C, 6 days Balkus, 1995 (45b)... 

Acrylics can also be bulk polymerized. One method for bulk polymerization involves coating a mixture of acrylic monomers along with a photoinitiator onto a film and uv curing to form the adhesive in place. Also being solventless, this can be an attractive method for making thick coatings. In addition, novel phase structure can be imparted by in place curing in some instances [eg, bicontinuous microemulsions (25)]. 

Chirality has become arguably the most important topic of research in liquid crystals today. The reduced symmetry in these organized phases leads to a variety of novel phase structures, properties, and applications. Molecular asymmetry imparts form chirality to liquid crystal phases, which is manifested in the formation of helical ordering of the constituent molecules of the phase. Similarly, molecular asymmetry imposes a reduction in the space symmetry, which leads to some phases having unusual nonlinear properties, such as ferroelectric-ity and pyroelectricity. 

Chovancova-Lovell, V. Pekarovicova, A. Fleming, P. 2006. Novel phase change inks for printing three-dimensional structures. J. Imaging Sci. Technol. 50 550-555. 

Fujimoto et al. [77] synthesized a novel phase by coupling a dodecylamino-substituted P-cyclodextrin (P-CD) to 3-glycidoxypropyl-derivatized silica gel. The surface coverage of this phase was reported as 0.37 xmol/m, which amounts to a surface coverage of 2.6 xmol/m for C12 chains (seven chains per fi-CD). An increase in shape selectivity was observed when compared with a conventional Cis monomeric phase as determined by selectivity differences between j9/m-terphenyl, j9/o-terphenyl, and coronene/phenanthro[3,4-c]phenanthrene solute pairs and was attributed to the localized high ligand density as constrained by the fi-CD platform structure. 

The potential for novel phase behaviour in rod-coil block copolymers is illustrated by the recent work of Thomas and co-workers on poly(hexyl iso-cyanate)(PHIC)-PS rod-coil diblock copolymers (Chen etal. 1996). PHIC, which adopts a helical conformation in the solid state, has a long persistence length (50-60 A) (Bur and Fetters 1976) and can form lyotropic liquid crystal phases in solution (Aharoni 1980). The polymer studied by Thomas and co-workers has a short PS block attached to a long PHIC block. A number of morphologies were reported—wavy lamellar, zigzag and arrowhead structures—where the rod block is tilted with respect to the layers, and there are different alternations of tilt between domains (Chen et al. 1996) (Fig. 2.37). These structures are analogous to tilted smectic thermotropic liquid crystalline phases (Chen et al. 1996). 

Improved catalytic performance, selectivity and resistance to fusion, over bismuth molybdate catalysts was reported by McClellan (90) for catalysts obtained by chemically combining bismuth, molybdenum, phosphorus, and silica. After calcination at 450°C, the bismuth phosphomolybdate-on-silica catalyst showed an X-ray pattern of mainly crystalline Bi2(Mo04)3 which subsequently was converted to a new, substantially amorphous, phase after calcination at 800°C. Substantially morphous meant that the X-ray diffraction lines were broad diffuse bands of low intensity. The pattern of lines for this novel phase indicated a scheelite structure. A special interaction of silica with bismuth molybdate was also suggested by Callahan et al. (91). 

This first section focuses on three major areas library generation method (mixtures and single compounds) chemistry (solid-phase and solution synthesis) and quality/speed (analytical and automation). Finally, the section ends with a chapter reviewing examples where combinatorial chemistry/rapid organic synthesis has been used for discovering novel lead structures for pharmaceutical purposes. 

A novel class of crystalline, microporous aluminophosphate phases has been discovered. It represents the first class of molecular sieves with framework oxide compositions free of silica. The new class of materials encompasses some fourteen reported three-dimensional microporous framework structures, and six two-dimensional layer-type structures. The three-dimensional structures include structural analogues of the zeolites sodalite and erionite-offre-tite. The novel phases can be synthesized hydro-thermally in the presence of organic amines and quaternary ammonium templates. The template is entrapped or clathrated within the crystallizing aluminophosphate network. After thermal decomposition of the template the three-dimensional molecular sieves have the general composition of Al303 1.0 ... 

Common approaches for the tailoring of nonmetallic (ceramic) materials properties involve topochemical methods (those where the crystal structure remains largely unaffected) and the preparation of phases in which one or more sublattices are alloyed. In principle, such materials are within the realm of CALPHAD. On the other hand, as has already been stated, extrapolation does not really aid the discovery of new or novel phases, with unique crystal structures. Furthermore, assessed thermochemical data for the vast majority of ceramic systems, particularly transition metal compounds, are presently not available in commercial databases for use with phase diagram software. This does not necessarily preclude the use of the CALPHAD method on these systems However, it does require the user to carry out their own thermodynamic assessments of the (n — 1 )th-order subsystems and to import that data into a database for extrapolation to nth-order systems, which is not a trivial task. 

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