Synthesis of Bottlebrush Polymers by Z -/ E -Specific Living Ring-Opening Metathesis Polymerization, Exhibiting Different Thermal Properties.

Synthesis of bottlebrush polymers (BBPs) and block copolymers by Z -/ E -specific living ring-opening metathesis polymerization (ROMP) of N-substituted-norbornene-2,3-dicarboximides containing long alkyl chains ( n -octadecyl, n -tetradecyl, etc.) has been attained by the vanadium(V)-alkylidene catalysts V(CHSiMe 3 )(ArN)[OC(CF 3 ) 3 ](PMe 3 ) 2 [Ar = 2,6-Cl 2 C 6 H 3 ( 1 ), C 6 F 5 ( 2 )] and V(CHSiMe 3 )(2,6-F 2 C 6 H 3 N)(OC 6 Cl 5 )(PMe 3 ) 2 ( 3 ). The ROMPs using 1 afforded the BBPs with exclusive Z selectivity (98 to >99% cis ) even at high temperature (up to 80 °C) in the presence of PMe 3 , whereas the ROMPs using 3 gave the BBPs with high E selectivity (90% trans ). These ROMPs proceeded in a living manner (even at 80 °C using 1 ), affording various (amphiphilic) block copolymers while maintaining high E / Z selectivity. The resultant Z - and E -selective BBPs especially prepared from N -( n -octadecyl)norbornene-2,3-dicarboximide possessed different melting temperatures due to different degrees of interpolymer alkyl side chain interaction (side chain crystallization).