Popout transitions in weakly stretched single-chain multi-block copolymers in poor solvents

We show that weakly stretched single-chain multi-block copolymers in poor solvents experience sudden changes in the number of domains when the end-to-end elongation distance of the chain is changed. The simplest symmetric transition of this type, occurring for a four-block copolymer, is analyzed using self-consistent field theory (SCFT) simulations and a simple free-energy model. The very simple model provides a surprisingly good description of the critical elongation at which the transition occurs as a function of the polymer characteristics.