Small-Angle X-Ray Scattering of Polymer Systems

Polymers are considered macromolecular chains of high molecular weight formed by monomers bonded covalently. They can be obtained from natural sources or from synthetic processes through different polymerization routes [1]. A number of both natural and synthetic polymers are able to form regular arrangements, that is, crystalline entities, under either quiescent or deformed states. Cellulose and natural 

Thermoplastic polymers are synthetic polymers that become plastic on heating and harden on cooling. PE, iPP, PET, and polyamides, among others, are typical examples of this type of polymers. Depending on the chemical and molecular structure and processing variables, they may or may not crystallize. Thermoplastic polymers that are able to crystallize have a significant amount of amorphous material, and therefore they are known as semicrystalline thermoplastic polymers. 

Handbook of Polymer Synthesis, Characterization, and Processing, First Edition. Edited by Enrique Saldivar-Guerra and Eduardo Vivaldo-Lima. 2013 John Wiley Sons, Inc. Published 2013 by. John Wiley Sons, Inc. 

Polymer crystals can be obtained from either dilute solutions or amorphous states (glassy or molten) [2, 3], Crystallization from dilute solutions usually gives polymer single crystals. Fischer, Keller, and Till reported the formation of polymer single crystals from dilute solutions 

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The problem of small-angle X-ray scattering of lamellar systems will be treated in the following chapters mainfy by means of biomembiane assets. Nevertheless, the concepts should generalfy ap fy to other lamellar systems, such as polymer systems. 

The former problem is a general problem not only for polymers but also for any other materials (atomic or low molecular weight systems). Although nucleation is a well-known concept, it has never been confirmed by direct observation due to the low number density of the nuclei to be detected with present experimental techniques, such as small angle X-ray scattering (SAXS). Therefore, one of the most important unresolved problems for basic science is to obtain direct evidence to solve the nucleation mechanism of any material. 

Hashimoto, T. (1985). Time resolved small-angle X-ray scattering studies on kinetics and molecular dynamics of order-disorder transition of block polymers. In Physical optics of dynamic phenomena and processes in macromolecular systems, (ed. B. Sedlacek), p. 106. Walter de Gruyter, Berlin. 

Powder formation in an LCVD system is a reflection of the polymer deposition mechanism. The size and number of particles may be taken as a measure of the polymerization-deposition mechanism or the status of an LCVD system. At one extreme is exclusive powder formation, as reported by Liepins and Sakaoku [7] at the opposite extreme is the formation of a continuous film in which no visible particles can be found. Even in the latter case, however, the work of Havens et al. [12] involving the use of small-angle X-ray scattering indicates that detectable domains... 

It has been predicted by theory that the polyelectrolyte stars can form different kinds of ordered structures in solutions at high concentrations. Likos et al. [93,94] pointed out the different crystal structures for polyelectrolyte stars with certain arm numbers and densities (see Fig. 11). This has been used to explain the anomalous structure with the concentrated polyelectrolyte star solutions. Ishizu et al. [95] successfully demonstrated this ordering by small angle X-ray scattering (SAXS) for concentrated PAA star solutions with arm number 30 and 97 (displayed in Fig. 12). No such phenomenon was seen for the polyelectrolyte star polymers under scrutiny here. The reason for this may be located in the finite polydispersity of the present systems that may suppress the formation of ordered phases. 

The l(Mig period of the regularly packed microdomains, as illustrated in Fig. 9.12, can be determined by the small-angle X-ray scattering. One may make a scaling analysis on the equilibrium domain sizes from the calculation of free energy changes as follows. In comparison to the macrophase-separated polymer blends, the microphase-separated diblock copolymer system contains mainly two... 

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