Robust carboxylated polymer pores from a cyclic peptide template

Functionalized pores that are stable to chemical degradation are attractive for use in a variety of applications ranging from sensing to catalysis. Herein, robust polymer nanotube bundles decorated with carboxylate groups inside the pores have been developed in two steps from a cyclic peptide template containing polymerizable norbornene units. The cyclic peptide forms nanotube bundles of ca. 35 nm in diameter. Polymerization of the exposed norbornene units gives peptide–polymer hybrid nanotube bundles of ca. 100 nm diameter that have improved thermal and chemical stability compared to cyclic peptide nanotubes. Hydrolysis of the ester linkage connecting norbornene to the peptide scaffold and removal of the peptide provide robust polymer pores of ca. 100 nm that are not only chemically stable, but also have carboxylate groups in the pores. Such nanotube bundles with carboxylate groups can be potentially used for encapsulation of cations or biomimetic ion transport.