Facile Syntheses of Cylindrical Molecular Brushes by a Sequential RAFT and ROMP "Grafting-Through" Methodology

Facile syntheses of cylindrical molecular brushes by a sequential reversible addition fragmentation chain transfer (RAFT) and ring opening metathesis polymerization (ROMP), RAFT and ROMP 'grafting through' methodology has been reported. The dual ROMF active and RAFT chain transfer agent containing both a norbornene and trithiocarbonate functionality, NB-TTC, was prepared in 89% yield by esterification. The practical advantages of this strategy include time efficiency and air insensitivity. The final brush polymer structures retain the trithiocarbonate end groups, so that it would be possible to follow with further 'grafting from' chain growth, because the ROMF active norbornenyl group is introduced into the initial RAFT chain transfer agents. The brushes bearing carboxylic acid groups also may be used for further chemical modifications, in addition to their observed pH responsive transformations.