A SCANNING TUNNELING MICROSCOPY AND TRANSMISSION ELECTRON-MICROSCOPY STUDY OF POLY(ETHYLENE OXIDE) FILMS

We present images of poly(ethylene oxide) films cast onto freshly clea ved mica and prepared for analysis by coating with a platinum-carbon f ilm. A number of structural forms were observed, including globular, f ibrous, and branched types. The basic unit from which all of these str uctures were formed was a rope of diameter 20 nm. The branched feature s were observed to be formed from folds of this rope. Particularly str iking images were obtained from boundaries between domains, showing a sharp separation between regions of the sample in which the polymer is found in the fibrous and the branched forms, Examination of the same samples by transmission electron microscopy (TEM) revealed identical s tructures. However, comparison of the scanning tunneling microscopy (S TM) and TEM images demonstrates that the TEM images exhibit lower vert ical contrast and fail to provide some of the structural detail which is apparent in the STM images.