Binuclear Schrock-Type Alkylidene-Triggered ROMP and Cyclopolymerization of 1,6-Heptadiynes: Access to Homopolymers and ABA-Type Block Copolymers

The molybdenum-based binuclear Schrock-type initiator 1,4-{Mo(N-2,6-(2-Pr) 2 C 6 H 3 )[OCMe(CF 3 ) 2 ] 2 CH} 2 C 6 H 4 ( 1 ) was used for the ring-opening metathesis polymerization (ROMP) of norborn-2-ene (NBE) and for the cyclopolymerization of a series of 1,6-heptadiynes, i.e., dimethyl dipropargylmalonate ( M1 ), diethyl dipropargylmalonate ( M2 ), di- tert -butyl dipropargylmalonate ( M3 ), 4-(ethoxycarbonyl)-1,6-heptadiyne ( M4 ), 4,4-bis(hydroxymethyl)-1,6-heptadiyne ( M5 ), and 4-(hydroxymethyl)-1,6-heptadiyne ( M6 ) to form the corresponding M n −X− M n block copolymers. The polymerization systems M1 - 1 (monomer M1 polymerized by the action of initiator 1 ) and M2-1 fulfilled the criteria of a class IV and class V living system, respectively. Poly- M1, poly- M2, poly- M3, and poly- M4 consisted of 40%, 50%, 58%, and 32% 1,2-(cyclopent-1-ene)vinylenes and 60%, 50%, 42%, and 68% 1,3-(cyclohex-1-ene)methylidenes, respectively. Finally, the block copolymers M2 25 - b - M1 25 -CH-1,4-C 6 H 4 -CH- M1 25 - b - M2 25, M1 35 - b - M2 35 -CH-1,4-C 6 H 4 -CH- M2 35 - b - M1 35, M1 25 - b -NBE 35 -CH-1,4-C 6 H 4 CH-NBE 35 - b - M1 25, M2 40 - b -NBE 26 -CH-1,4-C 6 H 4 -CH-NBE 26 - b - M2 40, NBE 50 - b - M1 35 -CH-1,4-C 6 H 4 -CH- M1 35 - b -NBE 50, and NBE 30 - b - M2 25 -CH-1,4-C 6 H 4 -CH- M2 25 - b -NBE 30 were prepared. Using AFM, films of M1 25 -CH-1,4-C 6 H 4 -CH- M1 25 were found to be homogeneous, while phase separation was observed for M1 25 - b -NBE 35 -CH-1,4-C 6 H 4 -CH-NBE 35 - b - M1 25 .