Visualizing Pattern Formation in Polymer Blends Using Near-Field Vibrational Infrared Imaging

In this presentation, the molecular sensitivity of scattering-type near-field scanning optical microscopy (s-SNOM) will be demonstrated by imaging an organic thin film with thickness gradient that continuously vary from zero to over 200 nm on different substrates. We will then present recent s-SNOM experimental results that show phase separation and nanoscale pattern formation in thin films of blended polymers. The evolution of nanoscale domains and hierarchical patterns as a function of composition will be discussed. The results may help to understand the sensitivity of s-SNOM chemical imaging at the molecular “finger print” region of electromagnetic radiation and to realize the capability of the technique to resolve nanoscale domains and phase separation in multicomponent organic thin films.