Synthesis and Aqueous Self-Assembly of ABCD Bottlebrush Block Copolymers
Eman Ahmed, C. Tyler Womble, Marcus Weck
Abstract
Tetrablock bottlebrush copolymers with three incompatible hydrophobic domains and one hydrophilic domain are prepared by a grafting-through approach using living ring-opening metathesis polymerization from norbornene end-functionalized hydrophilic, lipophilic, fluorophilic, and siliphilic macromonomers. The lipophilic and fluorophilic macromonomers are synthesized by the atom-transfer radical polymerization of styrene and pentafluorostyrene, respectively. The hydrophilic and siliphilic macromonomers are obtained by Steglich esterification of a norbornene-based carboxylic acid with monohydroxy-terminated poly(ethylene glycol) and poly(dimethylsiloxane), respectively. Bottlebrush copolymers are prepared with variations in the block sequence and block ratio and self-assembled in aqueous media. “Hamburger-like,” “worm-like,” and “trefoil-like” morphologies are observed through a cryogenic transmission electron microscope.