Two-Dimensional 13C Magic Angle Turning NMR Analyses of Dynamics in Poly(2-hydroxypropyl ether of bisphenol A)

Abstract

Two-dimensional solid-state 13C magic angle turning (MAT) NMR spectroscopy, for measuring and separating the line shapes of chemical shift anisotropy (CSA) in respective 13C species, has been applied to the study of dynamics in amorphous poly(2-hydroxypropyl ether of bisphenol A) (PHR). From the temperature dependence of the CSA line shapes, the flip motion of the phenylene ring is quantitatively analyzed; the phenylene ring undergoes a π-flip motion with standard deviations, σ, of 25° and 30−35° at 27 and 90 °C, respectively. Accompanying the flip motion, the main-chain fluctuational motion is revealed from the temperature dependence of the CSA line shapes of the phenylene ring quaternary carbons. The cone angle of the main-chain fluctuation is 10−15° and 12−20° at 27 and 90 °C, respectively. On the basis of the main-chain motion, we propose a model to account for the coincidences of the frequencies and the activation energies of the phenylene ring π-flip motion and γ-relaxation. In the model, the main-c...