A new polymacromonomer architecture with mixed branch segments of different lengths has been constructed through reshuffling of poly(tetrahydrofuran), poly(THF), segments in an electrostatic self-assembly and subsequent covalent fixation process. Thus, two types of electrostatically self-assembled polymacromonomer precursors 4a and 4b were prepared by the ion-exchange reaction between alpha-methoxy-omega-(N-phenylpyrrolidinium) poly(THF)s (la and Ib) (M-n = 3000 and 6200, respectively) and a poly(sodium acrylate) (DP = 52), respectively. By reshuffling of different poly(THF) segments in the two polymer precursors, 4a and 4b, a new electrostatically self-assembled precursor, 4[a,b], was obtained. The subsequent heat treatment of 4[a,b] effectively produced a covalently linked polymacromonomer, 5[a,b], having mixed branch segments through the ring-opening reaction of the pyrrolidinium salt groups in la and in Ib by carboxylate anions in the backbone poly(acrylate) component.