SCHEDULED MAINTENANCE
Solvent-control over monomer distribution in the copolymerization of 2-oxazolines and the effect of a gradient structure on self-assembly†
Abstract
One-pot synthesis of gradient copolymers by statistical copolymerization represents an elegant route to amphiphilic copolymers as a basis for micellar systems. Herein, we propose a robust strategy to control the monomer distribution along the gradient copolymer chain by appropriate selection of the polymerization solvent. The gradient formation was investigated for copolymerizations of the hydrophilic 2-methyl-2-oxazoline (MeOx) and the hydrophobic 2-phenyl-2-oxazoline (PhOx) using sulfolane and acetonitrile as the polymerization solvents revealing a striking difference. In sulfolane, a quasi-block (CP2) like character was observed, whereas acetonitrile led to a more gradient-like (CP3) copolymer. The monomer distribution was found to have an impact on the micellization behavior of both amphiphilic copolymers, which was also compared with the analogous block copolymer (CP1). CP1 led to the formation of the smallest micelles, followed by a somewhat larger structure formed by CP2, while CP3 self-assembles into significantly larger nanoparticles. These findings open up a route to new amphiphilic copolymer systems with precisely fine-tuned architecture.
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