Thickness-dependent crystal orientation in poly(trimethylene 2,6-naphthalate) films studied with GIWAXD and RA-FTIR methods

• Published in: Polymer (Guilford) Vol. 49; no. 7; pp. 1961 - 1967
• Main Authors: Liang, Yongri, Zheng, Meizhu, Park, Ki Ho, Lee, Han Sup
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2008; Elsevier
• Subjects: Applied sciences; Crystal orientation; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Poly(trimethylene 2,6-naphthalate); Properties and characterization; RA-FTIR; Structure, morphology and analysis; RA-FTIR; Crystal orientation; Poly(trimethylene 2,6-naphthalate); Ultrathin films; Melt crystallization; Molecular orientation; Naphthalate polymer; Size effect; Spin-on coating; Experimental study; Isothermal crystallization; Thin film
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2008.02.012

The thickness dependence of the crystal orientation of poly(trimethylene 2,6-naphthalate) (PTN) films was clearly demonstrated using the methods of two-dimensional grazing incidence wide angle X-ray diffraction (2D GIWAXD) and grazing incidence reflection absorption FTIR (RA-FTIR) spectroscopy. The 2D GIWAXD results showed that for films thicker than 200nm, the “c” axis (main chain direction) and “b” axis of crystal unit cell are almost parallel to the sample surface, whereas for thin films the “c” axis is preferentially perpendicular to the film plane in the crystalline phase of isothermally crystallized PTN films. The anisotropic orientation of the naphthalene rings in the isothermally crystallized PTN film was also confirmed. By analyzing the relative absorbance of the parallel band (1602cm−1) to the one of perpendicular band (917cm−1), the thickness dependence of the crystal orientation suggested by the GIWAXD results was also confirmed. Furthermore, the naphthalene rings in the isothermally crystallized thick films were found to lie flat on the film plane. The chain orientations derived from the GIWAXD and RA-FTIR results in this work were found to be consistent with the “flat-on” and “edge-on” lamellar orientation for the thin and thick films, respectively, which has previously been reported in many polymer systems.