Regioselective Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes with Ether Side Chains
2016
Kobayashi, Shingo | Fukuda, Kousaku | Kataoka, Maiko | Tanaka, Masaru
Allyl-substituted cyclooctenes with ether side-chains [methoxy, methoxy-terminated oligo(ethylene glycol)s, and tetrahydrofurfuryloxy group] were prepared as monomers and polymerized by ring-opening metathesis polymerization (ROMP) using Grubbs second-generation catalyst. In all cases, the ROMP of allyl-substituted monomers proceeded in a regio- and stereoselective manner to afford polymers with remarkably high head-to-tail regioregularity with high trans-stereoregularity. The regio- and stereoregularity of polymers were affected by the bulkiness of the substituent, and the ROMP of tetrahydrofurfuryloxy-substituted cyclooctene exhibited nearly perfect regio- (head-to-tail = 99%) and stereoselectivity (trans-double bond = 99%). Chemical hydrogenation of obtained polymers afforded model poly(ethylene-co-vinyl ether)s with precisely placed ether branches on every eighth backbone carbon. Differential scanning calorimetry (DSC) was used to study the thermal properties, and the hydrophilicity of polymers was evaluated by water contact angle measurement. The surface hydrophilicity of unsaturated polymers was effectively tuned by changing the side-chain length of oligo(ethylene glycol) groups while maintaining the hydrophobic character unchanged for saturated versions.
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