Structure-Property Studies

Structure-Property Studies.— NyIon-2 polymers and copolymers, poly-(2,5-dimethylterephthalamides), wholly aromatic polyamides containing methyl-substituted phenylene linkages, and copolyamides based on caprolactam and hexamethyleneadipamide have been studied and properties related to structure. 

Carbon-13 n.m.r. sequence analysis on aliphatic homo and co polyamides the nylon 6,6 type have been reported.  

Properties of polyamide-poly(ethylene terephthalate) mixtures have been evaluated with particular reference to viscosity, glass transition temperatures, and thermal stability studies. 

Nylon 12 has been studied by solution casting from a phenol-ethanol mixture and shown to isomerize from the y to the a form. The permeation character istics of nylon 12 monbranes have also been evaluated and shown to be related to structural features associated with uptake of water by the casting solution, and the composition of the water-methanol mixed solvent used as the gelation medium. 

Copolymer systems have also been studied and properties related to molecular structure and chain composition.  

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Oligomers as Model Compounds for Structure-Property Studies 563... 

Randic, M. (1991) Resolution of ambiguities in structure-property studies by use of orthogonal ized descriptors../. Chem. Inf. Comput. Sci. 31, 311-320. 

In any structure/property studies on potential applications of lignins, an important parameter is the molecular weight and molecular weight distribution (MWD). In recognition of this fact, a substantial number of papers... 

Solov ev, V.P Vamek, A. Anti-HIV activity of HEPT, TIBO, and cyclic urea derivatives Structure-property studies, focused combinatorial library generation, and hits selection using substructural molecular fragments method. J. Chem. Inf. Comp. Sci. 2003,43 (5), 1703-1719. 

Epoxy networks may be expected to differ from typical elastomer networks as a consequence of their much higher crosslink density. However, the same microstructural features which influence the properties of elastomers also exist in epoxy networks. These include the number average molecular weight and distribution of network chains, the extent of chain branching, the concentration of trapped entanglements, and the soluble fraction (i.e., molecular species not attached to the network). These parameters are typically difficult to isolate and control in epoxy systems. Recently, however, the development of accurate network formation theories, and the use of unique systems, have resulted in the synthesis of epoxies with specifically controlled microstructures Structure-property studies on these materials are just starting to provide meaningful quantitative information, and some of these will be discussed in this chapter. 

A tremendous number of various fragments are used in structure-property studies atoms, bonds, topological torsions , chains, cycles, atom- and bond-centered fragments, maximum common substructures, line notation (WLN and SMILES) fragments, atom pairs and topological multiplets, substituents and molecular frameworks, basic subgraphs, etc. Their detailed description is given below. 

This chapter will not belabor in great detail the synthesis and structure-property behavior of those systems that have been prepared within our laboratory. Rather, some of the basic concepts involved in preparing these hybrid sol-gel materials will be reviewed. An overview of methods, including those routes taken by other researchers, will be presented. However, greater emphasis will be given to those materials that we have prepared, primarily because only limited structure-property studies have been carried out by other workers in the field. Further details of our studies on many of the hybrid materials (initially denoted as ceramers ) can be found elsewhere (i-9). 

In this area some interest has lain firstly in the semi-synthesis of alkaloids from certain natural intermediates and secondly in functional group transformations in structural/property studies. 

Clerc, J.T. and Terkovies, A.L. (1990). Versatile Topological Structure Deseriptor for Quantitative Structure/Property Studies. Anal.Chim.Acta,235, 93-102. 

Grossman, S.C. (1985). Chemical Ordering of Molecules A Graph Theoretical Approach to Structure-Property Studies. Int.J.QuantChem., 28,1-16. 

Lucic, B., Nikolic, S., Trinajstic, N., Juric, A. and Mihalic, Z. (1995c). A Structure-Property Study of the Solubility of Aliphatic Alcohols in Water. Croat.Chem.Acta, 68,417-434. 

Randic, M. (1991f). Resolution of Ambiguities in Structure-Property Studies by Use of Orthogonal Descriptors. J.Chem.Inf.ComputSci.,31, 311-320. 

Randic, M. (1993c). Novel Molecular Descriptor for Structure-Property Studies. Chem.Phys. Lett., 277,478-483. 

Randic, M. and Trinajstic, N. (1993b). Viewpoint 4 - Comparative Structure-Property Studies the Connectivity Basis. J.Mol.Struct (Theochem), 284, 209-221. 

Anderson, D. G. Akinc, A. Hossain, N. Longer, R. Structure/property studies of polymeric gene delivery using a library of poly (beta-amino esters). Mol. Then 2005, 11, 426-434. 

Estrada, E., Ivanciuc, O., Gutman, I., Gutierrez, A. and Rodriguez, L. (1998) Extended Wiener indices. A new set of descriptors for quantitative structure-property studies. New J. Chem., 22, 819-822. 

Funar-Timofei, S., Kurunczi, L. and lliescu, S. (2005) Structure—property study of some phosphorus-containing polymers by computational methods. Polym. Bull, 54, 443-449. 

Grossman, S.C. (1985) Chemical ordering of molecules a graph theoretical approach to structure-property studies. Int. J. Quant. Chem., 28, 1-16. 

That work has been extended to provide even further reductions in the dielectric constants of aromatic condensation polyimides by physically incorporating selected diamic acid additives into low dielectric constant polyimide systems. The monomer selection for the synthesis of these additives was based on the results of the Langley structure-property studies on lowering the dielectric constant of polyimides.CL)... 

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