Preparation of homopolymers, copolymers or block copolymers of monomer units cycloolefinic

The invention relates to the production of homopolymers, co-copolymers or block copolymers from cycloolefinic monomer units characterized in that polymerization occurs in the presence of a catalyst of general formula (I), and optionally in the presence of an additive, wherein the substituents and indices have the following meaning: M is a metal from group VIII B of the periodic table of elements; E1, E2 are independently from each other an element from group V A of the periodic table of elements; Z is a bridging structural unit; Ar stands for annelated aryl units independent of each other; L1, L2 stands for formally uncharged Lewis base ligands; X means monovalent or bivalent anions; k means 1 or 2; l, m, n represent 1 or 2, whereby m x n = 1.