Surface Relaxations in Polymers

• Published in: Macromolecules Vol. 30; no. 25; pp. 7768 - 7771
• Main Authors: Liu, Y, Russell, T. P, Samant, M. G, Stöhr, J, Brown, H. R, Cossy-Favre, A, Diaz, J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.12.1997
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Surface properties; Monodispersed polymer; Surface properties; Amorphous polymer; Styrene polymer; Experimental study; Intramolecular mobility; Segmental movement; Molecular relaxation; Thin film
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma970869a

Near-edge X-ray absorption fine structure, NEXAFS, spectroscopy was used to investigate the relaxations of polystyrene, a typical amorphous polymer, near a free surface after the imposition of a small deformation. Using synchrotron radiation, the NEXAFS dichroic ratio was determined for both the Auger and total electron yield processes as a function of temperature to determine the orientation of the polymer in the first 1 and 10 nm from the free surface, respectively. Complete relaxation of the polymer was not seen for temperatures less than the bulk glass transition temperature. No evidence of enhanced mobility at the free surface was found. A planar relaxation of the polymer was found in the first nanometer from the free surface, whereas in the first 10 nm, the dominant relaxation was normal to the surface.