Inspired by complementary hydrogen bonding interactions between nucleobase pairs in DNA, we incorporate guanine and cytosine on acrylic polymers using regioselective Michael addition. Free radical polymerization enabled the preparation of a series of <i>n</i>-butyl acrylate and nucleobase-functionalized acrylate copolymers. Thermogravimetric analysis (TGA) revealed higher weight stability of guanine-containing copolymers than the cytosine-containing copolymer counterparts. Variable temperature FTIR spectroscopy verified the presence of hydrogen bonding in both copolymer systems and their blends. Guanine copolymers exhibited enhanced mechanical performance that the 2 mol% guanine copolymer formed a free-standing film, whereas 2 mol% and 4 mol% cytosine copolymers flowed at room temperature. 4 mol% guanine copolymers exhibited a plateau regime that was observed in all cytosine copolymers according to dynamic mechanical analysis. In addition, the secondary tan delta transition after the plateau region at 70 °C corresponded to hydrogen bond dissociation within the guanine domains. Variable temperature Small-angle X-ray scattering unveiled microphase-separated morphology for both copolymers, in which guanine copolymers exhibited enhanced microphase separation than cytosine copolymers. The stronger hydrogen bonding interaction in GuA copolymer contributes to the enhanced microphase-separated morphology up to 180 °C. Lap shear testing revealed the transition of cohesive failure to adhesive failure through the incorporation of complementary hydrogen bonding interaction.

DNA-inspired guanine and cytosine-containing acrylic copolymers as supramolecular adhesives

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ACS Fall 2022

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