Transformation of the Bromine End Group into Thiol in (Meth)acrylic Polymers Synthesized by Atom Transfer Radical Polymerization

The halogen end group of polymers prepared via atom transfer radical polymerization (ATRP) can be converted into other functional groups by different chemical modifications. Herein, a new method to modify the bromine end group into a thiol functionality in (meth) acrylic polymers synthesized by ATRP is reported for the first time. Thus, the bromine end group of several poly(methyl methacrylate)s was successfully converted into a thioacetate and then in a mercapto group by a controlled hydrolysis. This end-functionalization was confirmed introducing in situ a fluorescent group by thiol-ene click reaction with a synthetic alquene tethered to a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) fragment. In addition, two model reactions in which bromide ATRP initiators were transformed into new thiol-functionalized molecules proved that this methodology can be applied to either methacrylic or acrylic polymers synthesized by ATRP.