Green Manipulation of Microdomain Structures in Block Copolymer Thin Films using Density Fluctuating Supercritical Carbon Dioxide

Self-assembling block copolymers are now commonly utilized to obtain well-defined arrays of nanoscopic structures in polymer thin films. Here, we introduce the use of supercritical carbon dioxide (scCO$_{2})$ as an environmentally ``green'' alternative to typical external fields, i.e. high temperature annealing, used to enhance the ordering of the nano-arrays. Various scCO$_{2 }$conditions, including the density fluctuation ridge where anomalous swelling behavior and miscibility can be witnessed in homopolymer thin films, were used for poly(styrene-\textit{block}-butadiene-\textit{block}-styrene) (SBS) triblock copolymer thin films. The surface structures of the SBS thin films were then investigated by using GISAXS and AFM. The details of this experiment will be discussed in the talk.