Structural characterization of polymers

Smith et al. [1.127] reviewed the dielectric relaxation spectroscopy (DRS) as a method for structural characterization of polymers and proteins providing, among others, information about the water content and states of water. 

Two theoretical approaches for calculating NMR chemical shift of polymers and its application to structural characterization have been described. One is that model molecules such as dimer, trimer, etc., as a local structure of polymer chains, are in the calculation by combining quantum chemistry and statistical mechanics. This approach has been applied to polymer systems in the solution, amorphous and solid states. Another approach is to employ the tight-binding molecular orbital theory to describe the NMR chemical shift and electronic structure of infinite polymer chains with periodic structure. This approach has been applied to polymer systems in the solid state. These approaches have been successfully applied to structural characterization of polymers... 

The microindentation hardness technique has been used for many years for the characterization of such classical materials as metals, alloys, inorganic glasses, etc. Its application to polymeric materials was developed in the 1960s. The potential of this method for structural characterization of polymers was developed and highlighted to a large extent by the studies carried out in the Instituto de Estructura de la Materia, CSIC, Madrid. 

R. Saladino, V. Neri, A. R. Pelhccia, R. Caminiti, C. Sadun, Preparation and structural characterization of polymer-supported methyl rhenium trioxide systems as efficient and selective catalysts for the epoxidation of olefins, J. Org. Chem. 67, 1323-1332 (2002). 

This review deals with several types of polymer hosts that have been investigated. These include polyethylene oxide and its several modified forms, comb like polymers such as polyacrylates and inorganic polymers such as polyphosphazenes and polysiloxanes. Various instrumental techniques have been employed in the structural characterization of polymer electrolytes. The structural information obtained from methods such as Extended X-ray Absorption Fine Structure (EXAFS), X-ray diffraction methods, vibrational spectroscopy and nuclear magnetic resonance (NMR) have also been discussed. 

Structural Characterization of Polymers in Solution by Quasielastic Laser Light Scattering... 

Early structural characterization of polymers focused on solution properties and their relationship to molecular weight (Dawkins, 1986 Booth and Price, 1989 Yamakawa, 1971 Flory, 1969). Subsequently spectroscopic and chromatographic techniques were developed, and reviews are widely available (Tanaka, 1991 Campbell and White, 1989 Baldwin and Ver Strate, 1972 Hsu, 2004 Stuart, 2002 Koenig, 1999). This chapter describes various characterization techniques, including discussion of the classical methods of analysis, as well as NMR, SANS, and so on. The main modifications for the fourth edition include the addition of newer methods and results and an update of the references. 

Morgan AB, Gilman JW, Jackson CL (2001) Macromolecules 34 2735 Becker O, Varley RJ, Simon GP (2002) Polymer 43 4365 Becker O, Cheng Y-B, Varley RJ, Simon GP (2003) Macromolecules 36 1616 Vaia RA (2000) Structural Characterization of Polymer-Layered Silicate Nanocomposites, in Polymer-day nanocomposites, Pinnavaia JT, Beall GW (eds), John WUey Sons, p 229... 

Masenelli-Varlot, K., Vigier, G., and Vermogen, A. 2007. Quantitative structural characterization of polymer-clay-nanocomposites and discussion of an "ideal" microstructure, leading to the highest mechanical reinforcement. 

Vaia, R. A. 2000. Structural characterization of polymer-layered silicate nanocomposites. In Polymer-Clay Nanocomposites, T. J. Pirmavaia and G. W. Beall (eds.), pp. 229-263. Chichester, U.K. John Mley Sons. 

I. Ando, S. Kuroki, H. Kiarosu, T. Yamanobe, NMR chemical shift calculations and structural characterizations of polymers. Prog. Nucl. Magn. Reson. Spectrosc. 39 (2001) 79-133. 

Linares A., Acosta, J. L. (2004). Structural characterization of polymer blends... 

Catania (Italy) Author of more than 50 publications and of 18 international invited lectures. He is currently working in the field of characterization of polymers and copolymers. He is an editorial board member of Rapid Communications in Mass Spectrometry. Research interests Structural characterization of polymers by mass-spectrometric techniques MALDI for the analysis of polymers and copolymers chain statistics applied to copolymer sequence analysis MonteCarlo simulations Bivariate distributions of chain size, and composition in high conversion copolymers. 

Saladino, R., Neri, V., Pelliccia, A., et al. (2002). Preparation and Structural Characterization of Polymer-Supported Methylrhenium Trioxide Systems as Efficient and Selective Catalysts for the Epoxidation of Olefins, J. Org. Chem., 67, pp. 1323-1332 Saladino, R., Neri, V., Pelhccia,... 

This possibility is extremely useful for the structural characterization of polymer blends. The optical properties of the polymer layer can be described by a so-caUed effective dielectric function, which is a suitable average of the dielectric functions of the two components. Three averaging effective medium approximation (EMA)s -the linear, Maxwell-Garnett and Bruggeman EMAs - are widely used for this purpose [9]. These approximations differ in their spectral densities for a given volume fraction. 

R-6 Tsuge S. Structural characterization of polymers by pyrolysis-gas chromatography. 71 Anal Chem 1981 1 87-90. 

However, the structural characterization of polymers by NMR does not lend itself to an easy quantitative determination of the polymers being studied. Indeed, it is well known that the carbon atoms exist in different hybridization states with different relaxation times. Moreover, due to the Overhauser effect, decoupling by irradiation of the protons modifies the population of the excited atoms. Consequently, it is difficult to consider that the intensity of the signals is directly proportional to the population of carbon atoms which they represent. Nevertheless, for the determination of tacticity, one generally considers that all stereosensitive carbon atoms are in the same hybridization state and that the intensities of their signals are an accurate measure of the content in different x-ads. Figure 3.6 shows... 

Masenelli-Varlot K., gier G., Vermogen A., Gauthier C., Cavaille J. Y. (2007), Quantitative Structural Characterization of Polymer/Clay Nanocomposites and Discussion of an Ideal Microstructure Leading to the Highest Mechanical Reinforcement. J Polym Sci Part B Polym Phys, 45,1243-51. 

We suppose that introduction of new structural characterization of polymers as a new physical characteristic of polymeric nature essentially broadens general problems of scientific research of polymers. It principally increases possibilities of regulation of mechanical, thermal, electric, optical, and other properties, giving an impetus to creation of new scientific directions as it has already happened on the example of GB optics. The essential characteristic of this position except gradient is the angle between stmctural orientation and the direction of the gradient. We can regulate it in the interval 90° - 0°. 

Many reviews have been published on the application of IR spectroscopy to polymers, and you should examine them if you are concerned with a specific polymer system or application (see the general references at the end of this chapter). The numerous applications of IR spectroscopy to the study of polymers far exceed our limited time and space. The basic IR spectroscopic methods of structural characterization of polymers will be discussed in this chapter, and a few pedagogical examples will be given to illustrate the applications of IR spectroscopy. 

High resolution solution NMR is a most important tool for the structural characterization of polymers. The spectral selectivity is the most important advantage of NMR. Unfortunately, the spectral sensitivity is low. The S/N can be increased by signal averaging and the use of higher magnetic fields. However, both of these techniques are costly. It is clear that we will continue to see an increase in the applications of NMR to the characterization of polymers. 

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