Cleavable multiblock copolymer synthesized by ring-opening metathesis copolymerization of cyclooctene and macrocyclic olefin and its hydrolysis to give carboxyl-telechelic polymer

A novel cleavable multiblock copolymer was synthesized by ring-opening metathesis polymerization (ROMP) of cyclooctene (COE) and a flexible 27-membered macrocyclic olefin (MCO), which is acted as the spacer to collect the polymer structure block by block. MCO 2 was prepared via ring-closing metathesis of the long chain alkyldiene, and then 2 was wellconducted ROMP with COE to provide the multiblock copolymer [Poly(COE)-2]_m consisting of homo-Poly(COE) blocks and ringopened 2 segments with different molecular weights (M_n = 30.0 - 249.6 × 10³) and polydispersity index (PDI) within 1.45- .67 as variation of the feed ratio of COE to 2. The multiblock copolymer chain containing weak ester linkage can be cleaved under alkali condition to afford the carboxyl-telechelic Poly(COE) blocks with much lower molecular weights (M_n,_h 1/4 3.6-35.7 10³) and slight higher PDIs (1.65-1.88). The average block number on multiblock copolymer chain was obtained from the ratio of M_n toM_n,_h and was reached up to the value of 7-16.