Before doing so maleimide driven systems have been considered in an alternative third step, as Roth and coworkers have shown that the copolymerization of maleimide derivatives and DOT produces very efficiently an alternating copolymer. The combination of maleimide derivatives, MMA and DOT seems thus interesting to incorporate DOT into a PMMA chain, as the copolymerization of maleimide and methacrylate derivatives has been reported as well. We specifically have chosen in this third step phenyl maleimide (PhMal) as comonomer, knowing that the phenyl moiety can be monitored via double detection SEC (UV at 254 nm). Extra UV detection at 330 nm can discriminate the insertion of the thioester moiety from DOT to the aromatic detection for both PhMAl and DOT at 254 nm, although strictly the direct (absolute) comparison of the signal at 254 and 330 nm cannot be done since the absorption coefficient ε is different.