Synthesis of internal- and mid-alkyne functional polystyrene by atom transfer radical polymerization

Well-defined alkyne functional polystyrenes were prepared using α-bromoesters 2-bromo-2-methyl-propionic acid-4-hydroxy-but-2-ynyl ester (BPE) and 2-bromo-2-methylpropionic acid-but-2-ynyl diester (BPDE) as initiator by Cu-mediated Atom Transfer Radical Polymerization (ATPP) of styrene. The polymerization of styrene with BPE gives polystyrene containing internal-alkyne functionality whereas BPDE system gives polystyrene containing mid-alkyne functionality. In case of both α-bromoester initiators, the molecular weight of the polymer obtained was increased linearly against conversion keeping narrow molecular weight distribution. The molecular weight and molecular weight distribution of all the polymers were determined by Gel Permeable Chromatography (GPC) analysis. The structures of internal-alkyne and mid-alkyne functional polystyrenes were confirmed by 1H NMR spectroscopy.