Synthesis and Characterization of Four‐Arm Star Polystyrene Based on a Novel Tetrafunctional RAFT Agent

Reversible addition fragmentation chain transfer polymerization (RAFT) is a very versatile polymerization technique whereby the topology of the final polymer can be tailored using specific RAFT agents. The tetrafunctional RAFT agent, tetrabenzyl(1,3‐dithietane‐2,2,4,4‐tetrayl)­tetracarbanotrithioate, has not previously been used to synthesize polymers. Poly­styrene (PS) is synthesized using this tetrafunctional RAFT agent and advanced characterization is performed using spectroscopic and separation methods. In situ ¹H nuclear magnetic resonance spectroscopy (NMR) and size‐exclusion chromatography (SEC) are used to determine the topology of the resultant PS. The polymerization is followed by in situ ¹H NMR, using styrene‐d₈ rather than hydrogenous styrene. In situ ¹H NMR spectra show that the RAFT agent is incorporated into the polymer as a terminal group. Aminolysis of the star‐shaped PS is performed and the SEC and NMR results before and after aminolysis are compared. These results indicate that the expected star‐shaped topology of the polymer is achieved.