Thermally curable benzoxazine ring-containing polystyrene macromonomers were synthesized and characterized. 1,4-Dibromo-2,4-bis(bromomethyl)benzene and 1,4-dibromo-2-(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene. The resulting polymers were used in combination with 3-aminophenylboronic acid hemisulfate, for a Suzuki coupling. The obtained polymers, with amino groups in the middle or end of the chains, were reacted with formaldehyde and phenol to yield benzoxazine ring-containing macromonomers. In addition to the glass transition temperature of the polystyrene segment observed at ca. 105 degrees C, differential scanning calorimetry thermograms exhibit an exotherm at ca. 276 degrees C corresponding to the oxazine thermal polymerization. Both macromonomers undergo thermal curing with the formation of thermosets having polystyrene segments.