To validate our hypothesis, a series of polystyrenes with different chain lengths were first synthesized by ATRP using PDI-diBr (for comparison) and PDI-tetraBr, resulting in linear PDI-diPSs and four-arm PDI-tetraPSs, respectively (Figure ). Styrene was selected as the monomer due to its weak electron-donating ability, which may induce a moderate charge transfer process while minimizing the interference to the PDI aggregate emission. All polymers showed controlled polymer chain length (degree of polymerization, DP = 15 -100) and narrow polydispersity (Đ = 1.1 -1.2).