Norbornene substituted with amine groups gives rise to ring-opening polymerization, with W(CO)5(CPh2) or W(CO)3(mes) (mes = mesitylene) associated with C2H5AlCl2 and molecular oxygen. With a 1:1 mixture of the exo and endo isomers, turnover of ca. 350 mol of monomer/mol of W are observed. The polymer obtained, which is almost insoluble in most organic solvents, is soluble in polar media (water, alcohols) after quaternization of the amine group. They can also be more soluble if a molecular weight regulator such as 1-pentene is used. The cis/trans ratio of double bonds in the polymer is close to unity, indicating a statistical coordination of the monomer to the metallocarbene fragment. It is also possible to obtain a copolymer between the functionalized norbornene and norbornene or cyclopentene. With norbornene it is possible to incorporate up to 90% of functionalized norbornene in the copolymer. With cyclopentene a 1:1 copolymer is obtained. No higher incorporation of cyclopentene can be achieved probably for steric reasons.
ASJC Scopus subject areas
- Organic Chemistry