Fig. 4

Schematic representation of structure-function of copolymer-membrane interaction. Triblock copolymer membrane stabilization occurs via insertion of the hydrophobic PPO core block (red) and balanced by flanking of the two hydrophilic PEO blocks (blue) that are required to prevent complete translocation across the membrane. Without a second flanking PEO chain, diblock copolymers can also insert into the membrane, but insertion is at least in part dictated by the PPO end group. Here, the more hydrophobic end group, such as –C(CH₃)₃ (†), driving insertion and anchoring and the more hydrophilic end groups, such as –OH, retained at the solvent-polar head group interface. Variation in PEO (blue) and PPO (red) block lengths alters the hydrophobic/hydrophilic balance that is required for optimal membrane insertion and stabilization. Too high a PPO/PEO ratio and large size PPO group drives the copolymer deeper into the membrane and further exacerbates damage to the membrane