Scattering Techniques X-Ray, Light, and Neutron

The entropy associated with placement of the junctions is reduced by the stricture of the A-B junctions at the interface, while the conformational entropy is reduced by the restriction of chain motions within the confines of the domain boundaries.This is the ordered state and is characteristic of di-blocks as well as network-forming block copolymers. This ordered state can be detected by observing the periodicity of the A-domain-interphase-B-domain stucture by the scattering of x-rays, light, or neutrons. The order-disorder transition temperature, Tc, is measured by these techniques. 

This chapter deals with two rather separate topics spectroscopic methods involving vibrational spectroscopy, i.e. infrared (IR) and Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and a few other spectroscopic techniques and methods using scattering of various waves including X-rays, light and neutrons. 

There are of course many other techniques with which to study polymer systems. These include, for example, stress-strain curve analysis for the study of mechanical properties, thermal methods such as DSC and DTA, which focus on bulk properties of the system. In addition there are an ever growing variety of techniques which provide information at the molecular level. Surface phenomena can be studied by SIMS, ESCA and other electron spectroscopies as well as ATR-infrared techniques. Other properties can be studied by ESR, NMR, X-ray, light, and neutron scattering. 

The internal structure of polyelectrolyte block copolymer micelles such as their core radius Rc and micellar radius Rm can be determined by a variety of methods involving static and dynamic light scattering (SLS, DLS), small-angle X-ray (SAXS) and neutron scattering (SANS) as well as imaging techniques such as transmission electron microscopy (TEM) or atomic force mi-... 

CT provides no information on the chemical speciation of a material, only its physical structure. Light scattering techniques are of little use in the majority of silicones due to their high filler content, however X-ray diffractrometry and neutron scattering techniques can be utilized to probe filler content, dispersion and morphology [9-11] (see Figure 11.4). 

The experimental techniques for the study of conformational branched properties in solution are the same as used for linear chains. These are, in particular, static and dynamic light scattering, small angle X-ray (SAXS) and small angle neutron (SANS) scattering methods, and common capillary viscometry. These methods are supported by osmotic pressure measurements and, nowadays extensively applied, size exclusion chromatography (SEC) in on-line combination with several detectors. These measurements result in a list of molecular parameters which are given in Table 1. 

Asbestos can be determined by several analytical techniques, including optical microscopy, electron microscopy, X-ray diffraction (XRD), light scattering, laser microprobe mass analysis, and thermal analysis. It can also be characterized by chemical analysis of metals by atomic absorption, X-ray fluorescence, or neutron activation techniques. Electron microscopy methods are, however, commonly applied for the analysis of asbestos in environmental matrices. 

Various methods have been proposed to measure the thickness of an adsorbed polymer layer. Depending on the method, a different property of the layer is determined. For example, hydrodynamic and electroklnetlc techniques probe the extension of the tails and give a thickness which may exceed considerably the average thickness as obtained from ellipsometry or from the reflected or scattered intensity of visible light, of X-rays, or of neutron radiation. In this section we can touch upon Just a few aspects of the various techniques. 

Scattering techniques, such as light, x-ray, and neutron scattering, are extensively used to investigate various structural features of polymeric systems, including crystalline order and crystallinity, conformation, local structure, domain sizes, etc. 

The volume fraction profile can be obtained by scattering and reflection techniques. X-ray and neutron scattering are employed if the substrate is particulate, and X-ray, neutron, and light reflection is used when the substrate is a flat, homogeneous surface. 

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