Structure—property correlations

A wide range of nitroxidcs and derived alkoxyamincs has now been explored for application in NMP. Experimental work and theoretical studies have been carried out to establish structure-property correlations and provide further understanding of the kinetics and mechanism. Important parameters are the value of the activation-deactivation equilibrium constant K and the values of kaa and (Scheme 9.17), the combination disproportionation ratio for the reaction of the nilroxide with Ihe propagating radical (Section 9.3.6.3) and the intrinsic stability of the nitroxide and the alkoxyamine under the polymerization conditions (Section 9.3.6.4). The values of K, k3Cl and ktieact are influenced by several factors.11-1 "7-"9 ... 

Tian et al. [56] have studied poly(G-caprolactone)-silica and Sengupta et al. [57] have investigated nylon 66-silica hybrid systems and have observed that the phase separation started when Si/H20 mole ratio is increased above 2 and the resultant hybrid films become opaque. Gao [11] has reported similar observations on sol-gel-derived ionomeric polyethylene-silica system. A wide range of literatures is not available on this topic of mbber-silica hybrid nanocomposites, though Bandyopadhyay et al. [34,35] have reported the hybrid formation with different TEOS/H2O mole ratios from ACM and ENR and also demonstrated detailed structure-property correlation in these systems. The hybrids have been prepared with 1 1, 1 2, 1 4, 1 6, 1 8, and 1 10 TEOS/H2O mole ratios. Figure 3.14 shows the morphology of the ACM-silica hybrid composites prepared from different TEOS/H2O mole ratios. 

J. K. Borchardt and A. R. Strycker. Olefin sulfonates for high temperature steam mobility control Structure-property correlations. 

Physical metallurgy is concerned with the scientific study of materials. Phase transformations, recovery and recrystallization, precipitation hardening, structure-property correlations, characterization of microstructure by microscopy (optical, electron and field-ion), are some specific examples among the many topics covered under physical metallurgy. 

Kopinke F, Georgi A, Mackenzie K (2001) Sorption of pyrene to dissolved humic substances and related model polymers. 1. Structure-property correlation. Envion Sci Technol 35 2536-2542... 

Heteropolycondensation of Bis-silanols, III, with Diacetoxysilanes. Heteropolycondensation of bis-silanols, III, was investigated since this approach appeared to offer a relatively rapid preparative route to a number of various siloxane-modified poly(arylene carbonates) which were required in order to obtain structure-properties correlations for such polymers. 

The most important step in a structure-property correlation is to discover the set of relevant structural parameters that control the property, as well as any related and readily available property parameters. The identification of these parameters may be suggested by theoretical understanding or by empirical observations of experimental measurements. There are some generally useful methods to discover the independent variables [x,] for a specific property in a set of molecules, such as the boiling points of the normal paraffins. 

W. Radke, Chromatography of polymers, in Macromolecular Engineering Structure-Property Correlation and Characterization Techniques, vol. 3, K. Matyjaszewski, Y. Gnanou, L. Leibler, eds., Wiley-VCH, Berlin, Germany, 2007 A.M. Striegel, J.J. Kirkland, W.W. Yau, D.D. Bly, Modem Size-Exclusion Liquid Chromatography, Wiley, Hoboken, New Jersey, 2009. 

Bezeredi A, Mudra I, Pukanszky B, Structure/Property Correlations in Nucleated PP... 

Canadell, E. and Whangbo, M.-H. (1991). Conceptual aspects of structure-property correlations and electronic instabilities with application to low dimensional transition-metal oxides. Chem. Rev. 91, 965-1034. 

For appropriate comprehension of morphology and the concomitant structure-property correlations in nanocomposites, knowledge of the state and extent of nanofiller dispersion in the matrix is of paramount importance. Numerous methods have been reported in the literature in this regard, for instance, WAXD [6, 38], SAXS [8, 39], SANS [40], SEM, [6, 41], AFM [7, 42], HRTEM, STEM, EELS [43], SSNMR [44], EPRS [45], UV/vis/NIR, FTIR [46], Raman spectroscopy... 

Research in the area of new synthetic metal (synmetal) superconductors continues to be stimulated by rapid developments in the chemistry and physics of these materials.1 Synmetals are unique in that they have metallic properties even though they contain no metals. However, this field remains very much materials limited because, as yet, it is not possible to predict which new materials will exhibit metallic properties. This situation is improving because structure-property correlations have been developed recently that may be used to predict likely candidates for superconductivity in the 4,4 j5,5 -tetramethyl-2,2 -bi-l-3-diselenolylidene, often called the tetra-methyltetraselenafulvalene (TMTSF) class of materials.2... 

Brocchini S, James K, Tangpasuthadol V, Kohn J. Structure-property correlations in a combinatorial library of degradable biomaterials. J Biomed Mater Res 1998 42 66-75. 

One of the obvious objectives of metal ion incorporation into polymers is to modify the essential bulk properties of these polymers with regard to miscellaneous end-uses. To this end however, structure-property correlations although useful, are difficult to achieve, particularly when high polymer networks are involved. This section will highlight how metal-ion incorporation can affect thermal stability, electrical and other useful properties of the polymer systems of which they are part... 

The molecules shown in Figure. 7 represent nnlv a few of the materials that have been studied In LB film form. Nonetheless, a great deal more needs iti be done to tup (he vast wealth of opportunities available with organic systems. There will inevitahly be short-term opportunistic attempts aimed at discovering molecules for specific devices. However, there is a more pressing need for a systematic approach (hat will yield rules governing structure-property correlations, so us 10 enable scientists confidently to predict the molecular architecture of monolayer assemblies. See also Macromolecular Science. 

Structure-property correlations in primary expls have been addressed via IR spectroscopy (Ref 55). The time for deflagration to detonation as a function of chemical structure for the compd methylnitrotetra-pyrrole was investigated and the presence of the nitro group confirmed by IR analysis... 

Guimont et al, Structure—Property Correlations in Primary Explosives , SRI-TPR-75-2 (1975) 56) H.L. Barreveld, The Analysis... 

C.M. Tarver et al, Structure/Property Correlations in Primary Explosives , SRI-FR-76-2, Stanford Res Inst, Menlo Park, Contract N00024-... 

In the following sections, examples will be given of how structure-property correlations of these types have been used to make materials that are useful in technology or medicine. 

It can be stated that networks based on a simple formulation (one monomer reacting with a comonomer), obtained from the step-polymerization process will exhibit a homogeneous structure. This is the case for epoxy-amine networks (the most studied) and polyurethane networks that have been used very often as ideal networks for structure-property correlations. 

The results obtained were extended to novel series of photochromic systems. The important objectives for the future research include a) synthesis of new compounds b) more extensive and more detailed investigation of their physico-chemical properties in order to find structure-property correlations and c) modification of already known systems by incorporating them physically or chemically into liquid crystals or polymers in order to develop new effective materials based on the novel photochromic molecules. 

With respect to the various spectroscopic methods not discussed so far there are four methodologically different concepts of molecular modeling (i) quantum-mechanical methods which result structural and electronic information (ii) MM-based structural modeling, followed by a single-point MO-based computation of the electronic properties (iii) spectra simulation with given electronic parameters in cases, where structural parameters (e.g., distances such as used in protein modeling, see above) are involved in the simulation (iv) structure property correlations. The latter approach will be discussed briefly at the end of this Section (redox potentials) and in Section 4. 

In another example, Chavali et al. demonstrated that 2D connectivity indices can give good structure/property correlations in molybdenum-catalyzed epoxidation [53,54]. They used the Computer Aided Molecular Design (CAMD) environment, a powerful computational tool used in product design. The method uses optimization techniques coupled with molecular design and property estimation methods, generating those molecular structures that match a desired set of properties. 

The optical and PL spectroscopies have been undertaken to understand the structure-property correlations of this important family of triplet-emitting polymers. The red shift in the absorption features upon coordination of the metal groups is consistent with there being an increase in conjugation length over the molecule through the metal center. The trade-olf relationship between the phosphorescence parameters (such as emission wavelength, quantum yield, rates of radiative and nonradiative decay) and the optical gap will be formulated. For systems with third-row transition metal chromophores in which the ISC efficiency is close to 100%,76-78 the phosphorescence radiative (kr)y, and nonradiative (/cm)p decay rates are related to the measured lifetime of triplet emission (tp) and the phosphorescence quantum yield ([Pg.300]

As stated above, no information about the actual microscopic coupling mechanism can be extracted from the exchange energy Jex. As a consequence, numerous studies have explored the relevant structure-property correlations of dinuclear transition metal complexes LaM(/r-Lb)M Lc, namely the relation between the value of /ex and the geometry of the M(/r-Lb)M link. 

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