The synthesis of polymers with ultra‐high molecular weight by combining ROMP and acyclic metathesis reaction

Abstract Ring opening metathesis polymerization (ROMP) is widely used to prepare functional materials with various topological structures. However, it is difficult to prepare polymers with ultra‐high molecular weight (UHMW) directly. We found a new method to prepare UHMW polymers by combining ROMP and acyclic metathesis reaction. First, monomer NB‐2OH was polymerized by ROMP with different feed ratio of NB‐2OH/G3, and obtained well‐defined polymers P(NB‐2OH) n ( n = 50, 200, and 463). Then acyclic metathesis reaction was used to synthesize UHMW polymers. The results indicated that polymer P(NB‐2OH) z with higher molecular weight ( M w = 6067.3 kg mol −1 ) and narrower distribution (PDI = 1.58) could be obtained at 80°C for 5 min, when P(NB‐2OH) 463 was used as raw material with H 2 SO 4 /G3 = 10/1. Compared with polymer P(NB‐2OH)1990 ( M w = 5343.1 kg mol −1 , PDI = 1.61) prepared by ROMP directly, the new method tremendously shortens reaction time, lowers the requirement for the purity of monomer and produces UHMW polymers with narrower distribution. The compositions of prepared polymers were also confirmed clearly by post‐modification and 1 H NMR characterization.