Co-polymerization of maleimides and vinyl ethers: A structural study

We report on the thermally-induced and photoinduced polymerization of the electron-donating divinyl ether di(4-vinyloxybutyl)succinate (DVBS) and the electron accepting 1,5-bis(maleimido)-2-methylpentane (BMMP) and their monofunctional analogues, dodecylvinyl ether (DDVE), N-methyl-maleimide (NMM), and N-phenylmaleimide (NPM). We focus on the stoichiometry of the monomer constituents consumed in the polymerization and the structural identity and bonding configuration(s) of the polymer products. For both BMMP-DVBS and NMM-DDVE, FTIR and 1H NMR data indicate 1:1 stoichiometry for the resulting polymer. For both systems, the polymers are of the alternating donor and acceptor form (DA)n. This result holds for both photoinduced and thermally induced reactions. Structural NMR studies of polymers synthesized from both mono- and difunctional monomers indicate the presence of both cis and trans conformers of the acceptor at the D-A bond. This finding indicates that thermodynamic factors alone are not sufficient to explain the ratio of the conformers and either steric factors or features specific to the transition state play a significant role in determining the conformational distribution of the polymer.