Functionalized Polyethylene Synthesis Via ADMET Chemistry

Linear Copolymers of Ethylene and Polar Vinyl Monomers via Olefin Metathesis−Hydrogenation: Synthesis, Characterization, and Comparison to Branched Analogues

“…In addition to the “randomness” provided by their asymmetry, the comonomers contribute an even number of carbons to the polymer chain, similar to what would occur in true chain-addition copolymerization (each 22-carbon monomer, after loss of its two terminal carbons during ADMET, formally contributes nine ethylene units and one polar vinyl comonomer unit). The carboxylic acid monomer 2-(dec-9-enyl)-tridec-12-enoic acid ( 1 ) was synthesized by nucleophilic substitution of the dianion of dodec-11-enoic acid onto 11-bromoundecene; 11c, the corresponding methyl ester, methyl 2-(dec-9-enyl)-tridec-12-enoate ( 2 ), was synthesized by reaction of the carboxylate salt of 1 with methyl iodide . The analogous hydroxyl-substituted monomer docosa-1,21-dien-11-ol ( 3 ) was synthesized by CeCl 3 -mediated addition of undecen-11-yl magnesium bromide to 10-undecenal 16 (low yields and side products plague the conventional magnesium-mediated Grignard reaction).…”

“…The analogous hydroxyl-substituted monomer docosa-1,21-dien-11-ol ( 3 ) was synthesized by CeCl 3 -mediated addition of undecen-11-yl magnesium bromide to 10-undecenal 16 (low yields and side products plague the conventional magnesium-mediated Grignard reaction). Alcohol 3 may be acetylated under standard conditions to afford the acetate monomer, acetic acid 1-(dec-9-enyl)-dodec-11-enyl ester ( 4 ) 11b. All of these monomers may be purified by flash chromatography; 1 and 3 can also be crystallized from cold hexanes.…”

“…Similarly, ROMP/hydrogenation of 1,2-difunctionalized cycloalkenes has been employed to model polyethylenes with high contents of regio- and stereoregular alcohol and amine substituents. 6c, The post-polymerization functionalization of polyalkenamers by Rh-catalyzed hydroformylation,6b and of polyalkenamers and borane-substituted cyclooctene monomers by hydroboration/oxidation, have also been used to prepare linear functional polyethylene analogues with varying polar contents. The Wagener group has developed a versatile strategy utilizing acyclic diene metathesis polymerization (ADMET) of symmetrically substituted α,ω-dienes to make model polyolefins bearing a wide range of substituents at precise intervals along the chain (Scheme ) . The low polar content functional polyethylenes obtained through this method have compositions equivalent to 7−11 mol % polar comonomer incorporation and methylene run lengths of r = 18, 20, 22, or 26.…”

“…Chain-addition copolymers can contain very long run lengths and broad run length distributions, even at high comonomer contents, which play a major role in controlling crystallinity and physical properties. Furthermore, even at relatively long run lengths, the regular structures of “precisely” branched ADMET copolymers exert unique influences on solid-state structure and produce unusual thermal behavior. 11b-e,i-l,n,o, …”

Modeling Ethylene/Methyl Methacrylate and Ethylene/Methacrylic Acid Copolymers Using Acyclic Diene Metathesis Chemistry

“…Other studies focused on the preparation of model copolymers of ethylene with carbon monoxide ( 3 ), vinyl acetate ( 4a − d ), methyl acrylate ( 5a , b ), ethyl acrylate ( 6 ), styrene ( 7 ), vinyl chloride ( 8 ), and isobutylene ( 9 ). These ADMET polymers were made using symmetric α,ω-diene monomers followed by hydrogenation of the unsaturated polymer (see Figure ); − several hydrogenations were done using a tandem ADMET polymerization/heterogeneous hydrogenation method developed by Watson . Consistent with the methyl branch study mentioned above, the model functionalized polyethylenes ( 3 − 9 ) exhibit sharper, more defined melting endotherms and T m 's lower than their chain-made counterparts (except for 9a , which is completely amorphous).…”