Imaging phase-separated domains in conducting polymer blend films with near-field scanning optical microscopy

We present high-resolution images with near-field scanning optical microsco py to study phase separation in polymer films of poly(styrene) and poly(3-o ctyl-thiophene). Transmission and transmitted fluorescence near-field scann ing optical microscope images were taken for direct visualization of the in termediate steps of phase separation in a regime where small domain sizes p revent investigation by conventional microscopy. The interpretation of near -field data on samples with large or varying film thickness or topography a re also discussed, and a method for recognizing topographically induced art ifacts in a quantitative way is suggested. (C) 2001 Optical Society of Amer ica.