Precise Control over Molecular Blocks to Achieve Robust Mechanical Properties of Bioinspired Nucleobase-Containing Polymers

Inspired by nature, materials scientists are highly motivated to achieve efficient control over building blocks at the molecular level for the fabrication of robust materials. Highly specific supramolecular hydrogen bonding between complementary nucleobases provides us with a straightforward and feasible route to precisely placing molecular motifs in polymer materials. In this work, we have demonstrated that precise supramolecular hydrogen-bonding pairing of nucleobase-containing monomers endows the attained polymer network with prominent mechanical properties, including high toughness, outstanding energy dissipation, excellent damping capacity, and good crack resistance. Complementary nucleobases adenine- and thymine-containing monomers with long alkyl chains were prepared, and the influence of distinct solvents on their hydrogen bond (H-bond)-forming capacity was explored. The H-bond-supporting solvent such as chloroform gives a high association constant of 36.0 M-1, while the H-bond-competitor solvent such as N,N-dimethylformamide generates a weak binding of only 2.8 M-1. The covalent "locking" of the precise supramolecular pairing of building blocks results in the formation of well-defined networks with a high supramolecular cross-linking density and activation energy, manifesting outstanding mechanical properties. This work reports an efficient route to constructing robust polymer materials by precisely controlling the hydrogen-bonding pairing of bioinspired nucleobase-containing building blocks.