Part I Three-wave Resonance GIXD of Surface/Interface In-plane Reflection; Part II X-ray Diffraction Study of C60-based star model polymer

• Main Authors: Yi-Shan Huang, 黃玉山
• Other Authors: Shih-Lin Chang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/89058513175532091504

博士 === 國立清華大學 === 物理學系 === 87 === In the first part, three-wave resonance grazing incidence x-ray diffraction is realized for the first time by tuning the x-ray photon energy to match the incident wavevector with the coplanar momentum transfers of crystal surface in-plane reflections. Near the resonance energy, the observed specularly diffracted intensities decreasing at lower energies and increasing at higher energies or vice versa reveal the effects of reflection phases due to the coherent interaction of x-ray surface waves. This experiment thus provides a new way of direct phase determination for surface in-plane reflections. In the second part, a time-dependent x-ray scattering study is presented of the kinetics of the C60-based star polymer containing 6 urethane-connected polyether and the star model polymers containing 4, 3, and 2 urethane-connected polyether arms. By varying the temperature from 40℃ to -40℃, the order-disorder phase transition (recrystallization) of the polymers has been observed. Two crystalline domains with the periodicities of 4.5±0.6 A and 3.7±0.4 A were detected. The domain sizes ranging from 70 A to 250 A, the transition temperatures from -15℃ to 25℃ and the maximum percentage of recrystallization from 13% to 34% increase as the number of polyether arms increases. The x-ray scattering peaks of the order phase grow up as , where and are the initial intensity and the proportional intensity modulus, respectively. The relaxation time of the order phase is varying as a power law with respect to the reduced temperature : seconds for the C60-based star polymer containing 6 urethane-connected polyether; seconds for the star model polymer containing 4 urethane-connected polyether arms.