Orthogonal click chemistry methods for preparing amphiphilic polyproline block copolymers: Synthesis and self-assembly

Polyproline-based homo- and diblock copolymers featuring clickable side chains-specifically, alkyne and allyl-have been successfully synthesized using water-assisted controlled ring-opening polymerization. These precursor polymers were then quantitatively modified through azide-alkyne and thiol-ene click chemistry. Sequentially, triethylene glycol monomethyl ether azide (a hydrophilic component) and octane thiol (a hydrophobic component) were grafted onto the pre-cursor block copolymer via orthogonal click reactions. The resulting side-chain-modified polyproline (PLP) amphiphilic co-polymers maintain a PPII helical conformation similar to native polyproline in aqueous environments. Additionally, the self-assembly behaviour of these amphiphilic block copolymers was examined using various analytical techniques, including dynamic light scattering (DLS), transmission electron microscopy (TEM), fluorescence spectroscopy, and confocal microscopy. Imaging through TEM and fluorescence studies indicated that the self-assembled amphiphilic polyprolines display a vesicular morphology. Moreover, incorporating side-chain functionalities into the polyproline backbone enhances the fine-tuning and control of material properties, opening the door to potential applications.