Block bottlebrushes represent a class of macromolecular surfactants with advantages over traditional linear block copolymers and short-molecule surfactants for stabilizing oil/water interfaces. While the impact of architectural features such as backbone length, side chain length, and grafting density on bulk properties is well established, their behavior at liquid-liquid interfaces remains largely unexplored. Extensive molecular simulations were performed to assess the effect of varying side chain length and hydrophilic/hydrophobic ratio at increasing surface concentration on bottlebrush interfacial conformations by means of various structural metrics like the radius of gyration, end-to-end distances, and backbone orientation. At higher surface concentrations, the backbone does not adopt a rigid rod-like structure but acquires some flexibility induced by inner sidechain interactions and interactions with nearby polymers. The hydrophilic/hydrophobic ratio in the block bottlebrush appears to play a minimal role in the interfacial behavior compared to the effect induced by the sidechain length, which suggests that sidechains may have a bigger impact on how block bottlebrushes will perform at liquid-liquid interfaces. The effect of molecular parameters to Interfacial tension reduction was also quantified. Understanding these structure-property relationships provides a platform for designing bottlebrush architectures that could serve as the next-generation soft materials with superior emulsion stability and tailored interfacial characteristics.
