Analysis of polymers using electron energy-loss spectroscopy (EELS)
thesisposted on 2019-07-31, 03:59 authored by Ruchi Pal
Morphology determination of polymeric systems is important for the understanding of the structure-property relationships. Transmission electron microscopy (TEM) is a key tool for direct imaging of a structure at nanoscales, but often has contrast problems with polymers. Traditional solutions involve the use of heavy element stains to generate contrast. Advances in electron-based spectroscopy such as Electron Energy-Loss Spectroscopy (EELS), have enabled spectroscopic measurements directly in the TEM, resulting in high contrast and spatial resolution, without staining. This thesis deals with the study of energy-loss near-edge structure (ELNES) of the carbon K-edge in polymers. The chemical fingerprinting of several polymers was carried out via analysis and interpretation of the ELNES of their carbon Kedge. The fingerprinting analysis could help in effective mapping of nano-structures, and the involved interfaces, within multiphase polymeric systems. Finally, EELS was used to measure interfacial width in a polycarbonate-polystyrene bilayer by employing STEM-SI (scanning TEM-spectrum imaging).