Additionally, kinetic studies confirmed the chain-growth free radical polymerization behavior, resulting in polymers with a high molecular weight even at low conversion. Encouraged by these results, we then directed our efforts towards exploring the scope of these sequenceregulated polysulfones (Figure ). If a pentyl group was attached adjacent to the benzothiazole sulfonyl group, the resulting polymer exhibited a sequence equivalent to poly(vinylbenzothiazole-heptene-sulfone) (P3). Monomers with thiazole as the migration group yielded insoluble polymers, which hindered our ability to characterize the products (P4). The solubility could be increased through methyl substitution on the vinyl positions. SEC analysis revealed that the polymers had a Mn of 32.7 k with a dispersity of 2.82 (P5). However, benzoxazole-sulfonyl monomers produced insoluble polymer products (P6). By incorporating an additional methine group, we observed the occurrence of 1,5-aryl group migration, allowing us to obtain polysulfones with varied lengths of repeating units-a feat that is particularly difficult to accomplish with existing chain-growth polymerization methods (P8). In contrast, 1,3 or 1,6aryl migration did not take place when using monomers with modified alkyl spacers. Furthermore, using thiophene, pyridine, or pyrimidine as migration groups failed to yield any polymers. In summary, we have successfully developed a novel free radical polymerization process for α-olefins involving aryl group migration. This unique approach enables the synthesis of a diverse range of ABC sequence-regulated polysulfones in a "SO2-free" manner, surpassing the limitation of traditional polysulfones which can only achieve two alternating sequences. By extending this strategy to monomers with additional methine spacers, we can access polysulfones with varying main chain compositions. We firmly believe that our aryl group migration radical polymerization strategy will open up new possibilities