Entropically driven ring-opening metathesis polymerization (ED-ROMP) of macrocyclic olefin-containing oligoamides

Abstract The synthesis and entropically driven ring-opening metathesis polymerization (ED-ROMP) of a range of olefin-containing macrocyclic oligoamides using Grubbs “second generation” metathesis catalyst has been investigated. The macrocycles were prepared from α,ω-divinylamides by two methods. First, directly by ring-closing oligomerization at high dilution. Second, by a two-step procedure using acyclic diene metathesis (ADMET) polymerization followed by cyclo-depolymerization at high dilution. When one of the terminal vinyl groups was close to the amide group very little polymerization took place. This was probably due to the vinyl group reacting with the metathesis catalyst, followed by the amide carbonyl group coordinating strongly to the metal center, so inhibiting catalysis. When very concentrated solutions of the olefin-containing macrocyclic oligoamides in tetrahydrofuran at 56 °C were treated with Grubbs ‘second generation’ olefin metathesis catalyst, they readily underwent ED-ROMPs to give homopolymers or copolymers with DPs of >70. A copolymer with both amide and ester repeat units was prepared.