Phase separation and self-assembly of cyclic amphiphilic block copolymers with a main-chain liquid crystalline segment†
Abstract
A series of linear and cyclized amphiphilic block copolymers consisting of poly(acrylic acid) (AAm) and main-chain liquid crystalline (LC) poly(3-methylpentamethylene-4,4′-bibenzoate) (BBn) segments were newly synthesized. Solid state morphology was investigated by X-ray scattering. Linear AA21BB9AA21, cyclic AA33BB10, and cyclic AA51BB18 formed lamellar microdomains, where the BBn segment of cyclic AA51BB18 formed a smectic CA phase. On the other hand, cylinder-type microdomains were formed by linear AA44BB9AA44 and cyclic AA100BB9. These amphiphilic block copolymers were self-assembled in water to form vesicles or cylindrical micelles, depending on the polymer concentration of the initial THF solution. The response of these nanostructures against an electric field demonstrated that the vesicles formed from linear AA25BB14AA25 and cyclic AA51BB18 turned into substantially larger aggregates, likely due to the reorganization of the LC segment in the bilayer.