Surface Dynamics in Rubbed Polymer Thin Films Probed with Optical Birefringence Measurements. Schwab, Alexander D.; Agra, Dena Mae G.; Kim, Jae-Hoon; Kumar, Satyendra; Dhinojwala, Ali. Department of Polymer Science, University of Akron, Akron, OH, USA. Macromolecules (2000), 33(13), 4903-4909. CODEN: MAMOBX ISSN: 0024-9297. Journal written in English. CAN 133:120911 AN 2000:375549 CAPLUS

Measurements of optical birefringence were used to probe the relaxation of rubbed ultrathin polystyrene (PS) films on glass substrates. The glass transition temp., Tg, of the films dropped by 15-20 K as the film thickness decreased from 10 mm to 5.8 nm. Expts. on thick films (.apprx.10 mm) revealed that mols. closer to the polymer-air interface relax more quickly than mols. farther from the interface. These results are explained in the context of past exptl. studies of thermal properties of similar ultrathin polymer films.