STUDIES OF THE PHASE-STRUCTURE OF POLY(TETRAMETHYLENE OXIDE) BY VT/MAS C-13 NMR

The phase structure of poly(tetramethylene oxide) (PTMO) crystallized from the melt was investigated at –100 to 0 °C using high-resolution solid-state13C NMR with a variable-temperature/magic-angle spinning system. By using the differences in the longitudinal and transverse magnetic relaxation times, we found that solid PTMO consists of a crystalline phase, a crystalline-amorphous interphase, and an amorphous phase. For the crystalline component the α-methylene resonance, appearing at 72.9 ppm, exhibits two different T1C’s, 209 and 9.3 s, at 0 °C. In contrast, the resonances related to the amorphous and interfacial components, which are at 70.9 and 72.0 ppm, respectively, display the same T1C of 0.15 s but different T2C values of 7.8 and 0.099 ms, respectively. Similar results are obtained for the β-methylene carbon. The line-shape analysis of the total spectrum containing all the components shows that the mass fractions of the crystalline component, the crystalline-amorphous interphase, and the amorphous phase are 0.60, 0.22, and 0.18, respectively. The lamellar thickness is determined as 145 Å from SAXS. From these values, thicknesses of the crystalline, interfacial, and amorphous components are estimated to be 87, 16, and 26 Å, respectively. © 1990, American Chemical Society. All rights reserved.