Solvent annealing block copolymer

Annealing of a PS-PB-PS block copolymer in toluene solvent vapor

This movie shows a polystyrene - polybutadiene - polystyrene triblock copolymer film annealing during exposure to toluene solvent vapor as imaged with the Cypher ES AFM. When films are originally formed by spin casting from solution, block copolymers are known to organize into various microphase morphologies. However this morphology might not be the lowest energy state, so annealing often results in significant restructuring. The movie begins just as toluene vapor enters through the closed cell. These are 4 µm scans, so you can see not only changes to the microstructure but also near the end a couple holes open up as the film delaminates from the silicon substrate. We then digitally zoom into a smaller area and examine the microphase morphology changes in more detail.