Process for preparing polymers by means of ring-opening polymerization

Process for preparing polymers by means of ring-opening metathetic polymerization, comprising the following steps:

• a. providing a reaction mixture consisting of a cycloalkene or a cycloalkene mixture,
• b. adding a ruthenium compound of the general formula RuX1X2L1aL2b (I) where
• a=0 or 1, b=1 or 2, such that a+b=2;
• X1, X2=independently selected anionic ligands;
• L1=uncharged π-binding ligand;
• L2=N-heterocyclic carbene of the formula IIa, IIb or IIc
• where
• R and R′ are each independently selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, phenyl and p-methoxyphenyl;
• and
• R1 and R2 are each independently selected from the group consisting of hydrogen, (C1-C18)-alkyl, (C3-C8)-cycloalkyl, (C3-C7)-heterocycloalkyl, (C6-C14)-aryl, and (C3-C14)-heteroaryl;
• where
• R and R′ are each independently selected from the group consisting of H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, phenyl and p-methoxyphenyl;
• and
• R1, R2, R3, R4, R5, R1a, R2a, R3a, R4a, R5a are each independently selected from the group consisting of H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl and methoxy;
• where
• R is selected from the group consisting of H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, phenyl and p-methoxyphenyl;
• and
• R′ and R″ are each independently selected from the group consisting of hydrogen, (C1-C18)-alkyl, (C3-C8)-cycloalkyl, (C3-C7)-heterocycloalkyl, (C6-C14)-aryl, and (C3-C14)-heteroaryl;
• c. adding a chain transfer agent in a molar ratio in the range from 1:5 to 1:1000 based on the cycloalkene or the sum total of the cycloalkenes in the cycloalkene mixture,
• d. converting at a temperature within a range from 0° C. to 250° C.