Nucleobase functionalized supramolecular polymer enables the longevity and recyclability of thermoplastic elastomers due to the formation of physical crosslinks through hydrogen bonding (H-bonding). This work described the influence of H-bonding distribution on the thermoplastic properties and self-assembly of nucleobase functionalized triblock copolymers. RAFT polymerization afforded the synthesis of A-(AB)-A type acrylic triblock copolymers containing cytosine and ureido-cytosine (UCy) functionality. <sup>1</sup>H NMR confirmed the random incorporation of CyA and nBA through the monomer reactivity ratio estimation. DSC revealed the microphase- separated structure of cytosine and UCy-functionalized copolymers, where the glass transition temperature of the central block is similar to that of its random copolymer macro-CTA. Thermomechanical and morphological analysis addressed the effect of the central block H-bonding on self-assembly and microphase-separated morphology. Dynamic mechanical analysis (DMA) revealed multiple tan delta transitions correlating to the glass transition and H-bonding dissociation in the central and external blocks. The UCy-functionalized triblock copolymer possessed an extended plateau window on DMA compared to the cytosine analog. Cytosine- functionalized triblock copolymers exhibited a cylindrical microphase-separated morphology on small-angle X-ray scattering, while UCy-functionalized copolymers showed less ordered structure due to the enhanced H-bonding interaction. Incorporating UCy functionality into the soft block features improved tensile strength, extensibility, and toughness compared to the random analog. Thus, these A-(AB)-A nucleobase-functionalized block copolymers demonstrated the improved mechanical properties for application as thermoplastic elastomers.

Tailoring solid state properties of quadruple hydrogen bonding containing block copolymers

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.