The sequential and concurrent polymerizations of an ABC monomer (gamma-(epsilon-caprolactone) 2-bromo-2-dimethylpropionate) with a BCD monomer (alpha-hydroxyethyl methacrylate) are introduced. This novel polymerization method is a versatile concept to branched copolymers. The two monomers that polymerize by different chemistries, ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP), bear initiating centers that are for the type of chemistry that is on the opposite monomer. In this way, a branched copolymer is realized without going through a traditional multistep procedure. The branching density can be altered simply by the addition of the appropriate AB (epsilon-caprolactone) and/or CD (methyl methacrylate) monomers.