To enable controlled growth of polymer chains from the PDI scaffold, a bidirectional ATRP initiator was first synthesized by functionalization of PDI with two hydroxyl groups and then coupling with α-bromoisobutyryl groups, resulting in PDI-diBr (Figure ). However, due to its poor solubility (~0.5 mg mL -1 in chloroform), the synthesis yield was only ~14%. To address this issue, we synthesized a PDI derivative with four hydroxyl groups by using 3-aminopropane-1,2diol for the amidation, followed by the functionalization with four α-bromoisobutyryl groups, resulting in a tetra-directional ATRP initiator, PDI-tetraBr (Figure ). Thanks to its much better solubility (~4 mg mL -1 in chloroform), PDI-tetraBr was easily obtained under mild conditions with a yield of ~46%. The structures of both initiators were confirmed by H and C nuclear magnetic resonance (NMR) spectroscopies (Figures and).