A well-defined triblock copolymer (triBCP) was synthesized by sequential living polymerizations by using one ring-opening polymerization and two atom transfer radical polymerizations. Competitive hydrogen-bonding-induced microphase separations of epoxy resin and triBCP were investigated. The ordered microphase-separated morphologies were characterized by IR, DSC, TEM, and SAXS. In addition, we synthesized unprecedented μ-star copolymers presenting poly(N-octyl benzamide) (PBA) and poly(ε-caprolactone) (PCL) arms: a combination of chain-growth condensation polymerization, styrenics-assisted atom transfer radical coupling, and ring-opening polymerization, obtaining a well-defined PBA2PCL4 μ-star copolymer (Mn,NMR ≈ 12 620; PDI = 1.22). Preliminary examination of the PBA2-μ-PCL4 star copolymer revealed assembly nanofibers having a uniform diameter of ca. 20 nm.