Design of Amphiphilic, Biodegradable Functionalized Polyoxazoline Hybrid-Block Graft Copolymers Using Click Reactions

Hybrid molecular brushes (HMBs), or bottlebrush polymers, are polymeric constructs containing a linear polymeric backbone and polymeric side chains with different chemical characteristics. Hybrid-block graft copolymers (HCPs) are similar to traditional HMBs, except their backbone consists of more than one polymer. We developed a facile method for the synthesis of a family of amphiphilic, biodegradable HCPs composed of two blocks: a hydrophilic block of poly(ethylene glycol) and a hydrophobic block of poly(2-oxazolines) modified by side chains of polycaprolactone. This was achieved by modification of the precursor 2-oxazoline monomers with a thiol-containing compound via a thiol-ene click chemistry reaction, followed by ring-opening polymerization of the monomer initiated by a poly(ethylene glycol) methyl ether tosylate macroinitiator. Lastly, polycaprolactone side chains were grafted via ring-opening polymerization yielding the amphiphilic HCPs. Herein, we determined the critical micelle concentration (cmc), showed the uptake and partitioning of beta-carotene in the micelles, and studied the brush architecture. The chemical structure, molecular weight, and morphology of the functionalized backbone, block copolymers, and HCPs were also determined.

Automated summary

Hybrid molecular brushes (HMBs) are polymeric constructs with a linear polymeric backbone and polymeric side chains, while hybrid-block graft copolymers (HCPs) have a backbone consisting of more than one polymer. In this study, we developed a facile method for synthesizing amphiphilic, biodegradable HCPs composed of a hydrophilic block of poly(ethylene glycol) and a hydrophobic block of poly(2-oxazolines) modified by side chains of polycaprolactone. We determined the critical micelle concentration, investigated the uptake and partitioning of beta-carotene in the micelles, and studied the brush architecture of the HCPs.