Crystal Structure of Poly(hexamethylene 2,6-naphthalate)

Abstract

The crystal structure of poly(hexamethylene 2,6-naphthalate) (PHN) was identified by X-Ray diffraction and molecular modeling. The possibility of stress- or temperature-induced crystal transformation is also examined. The unit cell of PHN was found to be triclinic (P1 space group) with dimensions of a = 6.70, b = 5.66, c = 18.40 A, α = 79.0°, β = 145.0°. γ = 90.0°, and crystal density was 1.313 g cm -3 . It was assumed from the observed density (1.298 g cm -3 ) that the unit cell contains one repeating unit of a polymer chain. The hexamethylene unit in PHN backbone takes nearly all-trans conformation. The packing mode is of the face-to-face type relative to the naphthalene rings. The PHN polymer does not undergo crystal transformation by temperature and/or stress.