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From Polymerization Inhibition to Controlled Ring‐Opening Metathesis Polymerization of Macromonomers with Tertiary Amine Groups: The Effect of Spacer Chain †
Author(s) -
Zhao Tengda,
Zhu Kongying,
Yu Xiaoliang,
Yuan Xiaoyan,
Ren Lixia
Publication year - 2021
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.202100152
Subject(s) - romp , macromonomer , chemistry , polymer chemistry , polymerization , ring opening metathesis polymerisation , tertiary amine , metathesis , amine gas treating , ruthenium , methacrylate , polymer , organic chemistry , catalysis
Main observation and conclusion Ring‐opening metathesis polymerization (ROMP) is a powerful toolbox in preparation of bottlebrush polymers for its high activity. However, the ROMP of macromonomers with repeating tertiary amine groups, for example, poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA), is inhibited due to the coordination of nitrogen atom with ruthenium center ([Ru]) in the third generation Grubbs catalyst (G3). In this work, norbornenyl functionalized polystyrene‐block‐PDMAEMA (NB‐PS‐ b ‐PDMAEMA) macromonomers with different length of polystyrene (PS) spacers are prepared. The PS spacers provide non‐coordinating local environment to protect [Ru] in G3 from coordinating with tertiary amine groups. Kinetic studies show that the PS spacer with polymerization degree (DP) of 15 is enough to protect G3, and the polymerization is controlled. However, the PS spacer with DP of 5 is inhibited within 10 min. In situ proton nuclear magnetic resonance studies show that the [Ru] in G3 is active during the ROMP of NB‐PS 15 ‐ b ‐PDMAEMA 39 , which is inactive gradually for NB‐PS 5 ‐ b ‐PDMAEMA 42 . In comparison, the ROMP of NB‐PDMAEMA macromonomer without spacer chain is inhibited and the G3 catalyst is inactive from the beginning. By introducing non‐coordinating spacer chain with enough length, the ROMP of macromonomers with tertiary amine groups is controlled, which provides a new strategy for the preparation of bottlebrush polymers with functional amine groups.