Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging
AbstractWe have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate. (Figure presented) © 2012 American Chemical Society.
CitationOba T, Vacha M (2012) Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging. ACS Macro Letters 1: 784–788. Available: http://dx.doi.org/10.1021/mz3002269.
SponsorsThe authors thank Dr. Satoshi Habuchi (currently at KAUST, Saudi Arabia) for many helpful discussions. This work was supported by a Grant-in-Aid for Scientific Research No. 23651107 of the Japan Society for the Promotion of Science and by a Research Grant of Ogasawara Foundation.
PublisherAmerican Chemical Society (ACS)
JournalACS Macro Letters