Nanoscale Subsurface Morphologies in Block Copolymer Thin Films Revealed by Combined Near-Field Infrared Microscopy and Mechanical Mapping

Block copolymer (BCP) thin films are commonly characterized by techniques that either lack nanometric spatial resolution or the ability for subsurface characterization. In this work, we combine scanning near-field optical microscopy and atomic force microscopy mechanical mapping to probe the subsurface composition of poly(styrene-block-tert-butyl acrylate) thin film with nanometric spatial resolution and compare our results to a theoretical description. Our work demonstrates a novel imaging approach for interrogating the internal morphology of BCP thin films. A better understanding of subsurface morphologies will enable better design principles for nanolithography and templating thin films for photonics, photovoltaics, and tissue engineering.