Automated large-scale synthesis of supramolecular oligo(p-benzamide) block copolymers

A fully automated large-scale synthesis procedure has been developed that allows the preparation of supramolecular rod−coil copolymers on a 100 g scale. The new reaction cycle allows the stepwise growth of oligo(p-benzamide)s onto the chain end of amine-terminated polymers. Amine-terminated poly(ethylene glycol) (PEG, Mn = 5000 g mol-1) and poly(styrene) (PS, Mn = 2950 g mol-1) were prepared, and an octa(p-benzamide) oligomer block was grown from the chain end in an automated computer-controlled reaction cycle. Plotting the apparent molecular weight of the PEG copolymer against the number of reaction cycles revealed a linear relationship, which emphasized the high level of control this method offers. The block copolymers show strong aggregation in nonpolar solvents such as chloroform. Remarkably, transmission electron microscopy images of drop-cast chloroform solutions show perfectly uniform rodlike micelles for the PEG and the PS copolymer.