Supramolecular Triblock Copolymers Containing Complementary Nucleobase Molecular Recognition

Abstract

A novel difunctional alkoxyamine initiator, DEPN2, was synthesized and utilized as an efficient initiator in nitroxide-mediated controlled radical polymerization of triblock copolymers. Complementary hydrogen-bonding triblock copolymers containing adenine (A) and thymine (T) nucleobase-functionalized outer blocks were synthesized. These thermoplastic elastomeric block copolymers contained short nucleobase-functionalized outer blocks (M n ∼ 1K−4K) and n-butyl acrylate rubber blocks of variable length (M n ∼ 14K−70K). Hydrogen-bonding interactions were observed for blends of the complementary nucleobase-functionalized block copolymers in terms of increased specific viscosity as well as higher scaling exponents for specific viscosity as a function of solution concentration. In the solid state, the blends exhibited evidence of a complementary A−T hard phase, which formed upon annealing, and dynamic mechanical analysis (DMA) revealed higher softening temperatures. Morphological development of the block copolymers was studied using SAXS and AFM, which revealed intermediate interdomain spacings and surface textures for the blends compared to the individual precursors. Hydrogen-bonding interactions enabled the compatibilization of complementary hydrogen-bonding guest molecules such as 9-octyladenine.

Thymine- and Adenine-Functionalized Polystyrene Form Self-Assembled Structures through Multiple Complementary Hydrogen Bonds

“…There is much interest in supramolecular structures based on complementary multiple-hydrogen-bond arrays prepared from synthetic polymers presenting nucleotide bases on their side chains [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The binding forces in systems featuring multiple hydrogen bonds can be tuned, leading to inter-association equilibrium constants (K A ) ranging from several hundred up to more than 10 6 [21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

Advances in the Development of Supramolecular Polymeric Biomaterials

“…Introducing complementary guest molecules resulted in selective uptake into the nucleobase-containing domains, which may potentially extrapolate toward use in drug delivery and biological applications. 64 An interesting feature article on the incorporation of nucleobases and other complementary hydrogen bonding functionalities into well-defined block copolymers was reported. The design of synthetic macromolecules based on multiple noncovalent interactions is inspired by the way nature's biopolymers (nucleic acids and proteins) assemble into complex structures to achieve function.…”

Self-Assembled Structures of Diblock Copolymer/Homopolymer Blends through Multiple Complementary Hydrogen Bonds

“…The values of K A can be tuned from several hundreds to greater than 10 7 for polymer chains capable of forming multiple hydrogen bonding interactions [44][45][46][47][48][49]. The most important multiple hydrogen bonds are those found in complex biological systems, in particular, in DNA, a near-perfect example of a macromolecular structure in polymer science.…”