Fig. 4
From: Nanostructured polymer films with metal-like thermal conductivity
Structural characterization using synchrotron X-ray scattering. a Illustration of the experimental setup and the orthorhombic unit cell of crystalline polyethylene. The incident beam is perpendicular to the drawn direction. The lattice constants were obtained as a = 7.42, b = 4.95, c = 2.54 Å, where c-axis is the chain direction. b Wide angle X-ray scattering (WAXS) patterns from the ×1, ×10, and ×110 films. Characteristic Bragg scattering by the {hk0}and {hk1} plane groups were observed. The {hk0} group appears perpendicular to the draw direction. c Small angle X-ray scattering (SAXS) patterns from the ×1, ×10, and ×90 films, which clearly show an isotropic-to-anisotropic transition. d First-order orientation parameter and the effective crystallinity obtained from WAXS. e Scattering intensity linecuts of the SAXS patterns along the draw direction. Two humps appeared at scattering vectors that differ by a factor of two, suggesting a periodic structure with a repeating unit consisting of alternating crystalline and amorphous phases (Supplementary Note 4). The humps moved toward a smaller q with increasing draw ratio, indicating an increase in the period length. f The fraction of amorphous region in one periodic unit as a function of draw ratio (Supplementary Fig. 14). The blue circles were directly extracted from the SAXS data, while the shaded zone marked the range (±40%) of fitted data which were used in the one-dimensional thermal model (Supplementary Note 5). The red squares recast the crystallinity data in Fig. 4d. Inset is the normalized electron density profile obtained from SAXS analysis (Supplementary Note 4)
