The synthesis of bottlebrushes with improved longer side chains by combining grafting through and grafting from methods

Abstract

Bottlebrushes have intensive applications in photonics, surfactants, supersoft elastomers, medical imaging, drug delivery and nanomaterials owing to their unique morphology and properties. While the traditional grafting from method required low monomer conversion to avoid gelation, and resulted shorter side chain length. Compared with the traditional grafting from method, the bottlebrushes with improved longer side chains were successfully prepared by combining grafting through and grafting from methods. In this approach, RAFT and ROMP polymerizations were used in sequence to synthesize a series of main chains: including PNB-PMA7, PNB-PMA13 and PNB-PMA25. RAFT polymerization was then used to prepare bottlebrushes with different kinds of main chains under the same conditions. In the meantime, homo-polymerization of PMA was appeared inevitably, which was related to the polymerization time. Owing to the greater molecular weight of PNB-PMA13 and PNB-PMA25, the polymerized solutions transformed into gel in shorter time, and resulted to the lower proportion of homo-polymerization (<11%). Compared with PNB-SCS as main chain, the side chain’s degree of polymerization increased from 41 to 80 when PNB-PMA13 was used as main chain.