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, M-n = 5000 g mol(-1)) and poly(styrene) (PS, M-n = 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 c ontrol 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.