Monomer Sequence Regulation in Main and Side Chains of Vinyl Copolymers: Synthesis of Vinyl Oligomonomers via Sequential Atom Transfer Radical Addition and Their Alternating Radical Copolymerization

We propose a novel strategy of monomer sequence regulation in main and side chains of vinyl copolymers using sequential atom transfer radical addition (ATRA) for maleimide-ended sequence-regulated vinyl oligomonomers and their alternating radical copolymerization with styrene. To establish this strategy, a series of sequence-regulated vinyl oligomers were prepared by the ATRA of styrene (S) or methyl acrylate (A) to a halide-possessing A or S unit (methyl alpha-bromopropionate or 1-phenylethylhalide). The obtained halide-ended sequence-regulated vinyl oligomers were converted into maleimide-ended oligomonomers by S(N)2 reaction with the potassium salt of furan-protected maleimide (M) followed by deprotection. The maleimide-ended oligomonomers were then radically copolymerized with styrene in an alternating fashion to result in sequence-regulated vinyl copolymers consisting of a controlled monomer sequence (SA, AS, AA, and SS) in the side chain and an alternating sequence (MS) in the main chain. The solubility of the copolymers depended on not only the monomer composition but also the sequence of the side chains, whereas the thermal properties were negligibly affected by the side-chain monomer sequences.