Functionalized polyethylene via acyclic diene metathesis polymerization: Effect of precise placement of functional groups

The preparation of a variety of model functionalized polyethylenes using step polymerization techniques is described. Specifically, the synthesis and preliminary thermal characterization of sequence-ordered ethylene-co-acrylate, -co-styrene, and -co-vinyl chloride polymers with precisely defined ethylene run lengths is reported. Unsaturated precursor polymers with pendant groups separated by a precise number of carbons are prepared by acyclic diene metathesis (ADMET) polymerization, which upon hydrogenation of the olefin linkages become formally ethylene/polar monomer copolymers. The only variable in the microstructure of these copolymers is the identity of the pendant group allowing the strict comparison of various `comonomers' on melting point. The synthesis of the necessary symmetric diene monomers with central pendant alkoxycarbonyl, phenyl, and chloride groups is outlined. Preliminary thermal analysis shows these copolymers to melt sharply with a trend of increased melting point depression with increasing steric bulk of the pendant group.