Role of solvent quality on the morphology of concentrated block copolymer thin films

In the last two decades, self-assembled block copolymer (BCP) thin films have received major interest as they have found applications in nanoelectronics, batteries, membrane filtration and drug delivery. There are experimental methods for tuning phase behavior of self-assembled block copolymer as each one brings some advantage into the way of controlling the self-assembly process. While solvent vapor annealing has been found to be very useful, there is no clear framework on how to control the different parameters such as solvent quality, temperature, and annealing vapor pressure for achieving a desired morphology in copolymers. Moreover, for the case of symmetric triblock or higher block copolymers, the formation of loop/bridge conformation can have a significant impact on the morphology and mechanical properties of the material where experimental limitations still exist in characterizations of loop/bridge conformations. In the present work, we employed a coarse-grained molecular dynamics simulation to investigate the effects of solvent quality and chain stiffness on the phase behavior of symmetric ABA triblock copolymer focusing on loop/bridge conformations for different morphologies. The results demonstrate the correlation between the solvent quality, chain conformations and phase behavior of the ABA copolymer.