Structural Investigation of Poly(ethylene furanoate) Polymorphs

alpha and beta crystalline phases of poly(ethylene furanoate) (PEF) were determined using X-ray powder diffraction by structure resolution in direct space and Rietveld refinement. Moreover, the alpha' structure of a PEF sample was refined from data previously reported for PEF fiber. Triclinic alpha-PEF a = 5.729 angstrom, b = 7.89 angstrom, c = 9.62 angstrom, alpha = 98.1 degrees, beta = 65.1 degrees, gamma= 101.3 degrees; monoclinic alpha'-PEF a = 5.912 angstrom, b = 6.91 angstrom, c = 19.73 angstrom, alpha = 90 degrees, beta = 90 degrees, gamma = 104.41 degrees; and monoclinic beta-PEF a = 5.953 angstrom, b = 6.60 angstrom, c = 10.52 angstrom, alpha = 90 degrees, beta = 107.0 degrees, gamma = 90 degrees were determined as the best fitting of X-ray diffraction (XRD) powder patterns. Final atomic coordinates are reported for all polymorphs. In all cases PEF chains adopted an almost planar configuration.