Polyacrylonitrile (PAN)-based copolymers are widely recognized as crucial precursors for the production of high-performance carbon fibers. In pursuit of broadening the array of PAN-type copolymers, we embarked on the synthesis of monomers adorned with diverse side-chain functionalities (Figure ). Our initial endeavors involved the preparation of monomers bearing various phenyl substituents-specifically, methyl, bromo, and trifluoromethyl groups. These new monomers were readily polymerized, yielding a series of corresponding copolymers (Co-2-Co-4). The method was extended further to include copolymers with benzylic moieties, five-and six-membered carbocycles, as well as oxy-heterocycle (Co-5-Co-8). The introduction of dual electron-donating substituents around cyano moiety led to the generation of copolymers featuring quaternary carbon centers (Co-9). During this process, not only was the cyano migration tactic efficacious, but also the steric hindrance exhibited minimal disruption to the copolymerization. Additionally, the thermal attributes of these copolymers were assessed by DSC and TGA (Figures S15- ). It is noteworthy that the Tg of all polymers has only one value. This consistency in Tg not only underscores the homogeneity within the polymer structure but also serves as testament to the successful implementation of our strategic approach to constructing sequence-defined copolymers.