Amphiphilic Random Cyclocopolymers as Versatile Scaffolds for Ring-Functionalized and Self-Assembled Materials

Abstract

Building cyclic units into amphiphilic copolymers is promising to produce ring-functionalized and self-assembled materials with unique properties. In this work, we developed versatile self-assembly systems of amphiphilic random cyclocopolymers in organic and aqueous media and the solid state to create nanoaggregates and microphase separation materials functionalized by cyclic oligo(ethylene oxide) units. For this purpose, random cyclocopolymers consisting of hydrophilic oligo(ethylene oxide) rings and hydrophobic alkyl groups were synthesized, into which the in-chain ring units were introduced via the cyclocopolymerization of divinyl monomers carrying oligo(ethylene oxide) spacers. Typically, a cyclocopolyacrylamide bearing hydrophobic butyl groups self-assembled into nanoaggregates in chloroform and recognized a dibenzylammonium salt as a guest molecule with the in-chain rings, while the cyclocopolymer also formed thermoresponsive micelles in water and nanoaggregates and showed lower critical solution temperature-type solubility. Random cyclocopolymers carrying octadecyl groups afforded crystallization-driven microphase separation of their pendants in the solid state, giving sub-5 nm lamellar structure materials with the alternating layers of hydrophilic rings and crystalline octadecyl groups.