Impact of Aspect Ratio Control of Nanorod Surfactants on Shaping Block Copolymer Particles

Self-assembly of block copolymers (BCPs) within interface-engineered emulsion droplets is a simple and powerful tool in producing shape-controlled polymeric particles. In this talk, we describe the influence of nanorod (NR) length on manipulating interfacial properties of BCP particles. A series of cylinder- and lamella-forming polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and aspect ratio-controlled NRs were used, where the ratio of the NR length to the size of the NR-hosting domain (l/L) was tunable in a range from 0.07 to 2.40. Selective arrangement of NRs on the P4VP domain of the particle surface enabled the production of lens-shaped particles and striped ellipsoidal particles. In particular, the value of l/L was the key parameter in determining the location of the NRs in the BCP particles. Lens-shaped particles were produced only for 0.36 ≤ l/L ≤ 0.96, whereas ellipsoidal particles were formed for much wider range of l/L ≥ 0.83 without upper limit. This difference is attributed to larger entropic penalty for the NRs confined within the cylinders than that within the lamellae. The dynamics of NRs at the interface boundary of BCP particles was also investigated by performing a dissipative particle dynamics simulation of the NRs within a confined BCP emulsion system.