In-house simultaneous collection of small-angle X-ray scattering, wide-angle X-ray diffraction and Raman scattering data from polymeric materials

Abstract

An in-house X-ray scattering system, which can simultaneously measure small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) data, as well Raman scattering data, has been developed to study the phase transitions of polymeric materials. To date, these types of measurements have been limited to synchrotron radiation. The present system is an in-house SAXS system combined with a WAXD detector and a Raman spectrometer. A rotating-anode X-ray generator and multilayer optic are employed to provide a high-flux X-ray beam. Two two-dimensional hybrid pixel detectors are utilized for the rapid-scan time-resolved SAXS and WAXD measurements. The Raman unit consists of a compact probe with a near-infrared excitation laser operating at a wavelength of 1064 nm. This long-wavelength laser produces less fluorescence than conventional excitation lasers with wavelengths of 532 or 785 nm. The performance of this system was tested by investigating the thermally induced ferroelectric phase transition of vinylidene fluoride–trifluoroethylene (VDF-TrFE) copolymers. It has been demonstrated that the combination of SAXS, WAXD and Raman techniques gives useful information for revealing the relationship between the structural change in the crystal lattice and the morphological change in the lamellar stacking mode in polymer samples of complicated hierarchical structure.