Characterization of Polymer Morphology by Scattering Techniques

Institut Charles Sadron, CNRS-Universite de Strasbourg, Strasbourg, France 

Thanks to the newly built neutron large-scale facilities, successes in polymer science were immediate in the mid-1970s [9]. Neutron scattering experiments gave the first direct confirmation of the Gaussian behavior of polymer chains in the solid state as was predicted earlier by Flory [10]. They further revealed the chain conformation in semi-dilute solutions, which confirmed the relevancy of extending scaling 

Polymer Morphology Principles, Characterization, and Processing, First Edition. Edited by Qipeng Guo. 2016 John Wiley Sons, Inc. Published 2016 by John Wiley Sons, Inc. 

A monograph centered on polymer morphology should undoubtedly include a chapter on these techniques. This chapter is therefore focused on the possibilities offered by X-ray and neutron scattering/diffraction for determining the structure of polymer systems. These techniques are often complementary as X-ray photons and neutrons do not see matter the same way. The difference of neutrons versus X-rays lies in the way they interact with atoms X-rays interact with the electron cloud, while neutrons interact with the nucleus. Neutrons have an unquestionable advantage over X-rays when polymers are at stake thanks to the difference in scattering amplitude between hydrogen and deuterium, as is detailed below. 

The field of radiation scattering studies of polymers is a vast one, and cannot be treated in only one chapter. Consequently, this chapter is restricted to specific examples that are intended to present the potentialities of the scattering techniques. It is divided into three main sections a short presentation of the minimum theory to understand the concepts, the discussion about the notion of contrast factor, and finally a series of relevant examples taken from various systems. 

---

A wide variety of analytical techniques, such as wide-angle X-ray scattering (WAXS), FTIR, DSC, thermogravimetric analysis (TGA), solid-state NMR and mass spectrometry, are used to characterize the structures of polymer samples coalesced from their CD-IC crystals. The results of these observations are always compared with those obtained for as-received or as-synthesized, or melt or solution processed samples of the same polymers. In this manner, we attempt to assess process-dependent differences in their organization, such as morphologies, crystallinities and even the conformations adopted by their constituent polymer chains. 

The aspects of two phase polymer blends which most interest the physical scientist are those which concern the morphology and the interface. The interface is characterized by the interfacial tension and interfacial thickness and these affect the mixing process, morphology and properties. The morphology can be characterized by various techniques such as microscopy and scattering methods. A full description of the engineering and mechanical aspects of polymer blends is to be found in Volume 7, Chapter 4. 

---