Phase Behavior of Adenine-Containing Block Copolymer

Nucleobase-containing polymers have received great attention for their complementary multiple hydrogen bonding between nucleobases. However, their polymerization is difficult due to poor solubility in a solvent. In this study, we successfully synthesized adenine-containing block copolymers, poly(9-(4-vinylbenzyl)adenine)-block-polystyrene (PVBA-b-PS), using reversible addition–fragmentation chain transfer (RAFT) polymerization in polar solvents of dimethyl sulfoxide and N,N-dimethylformamide and characterized them by size exclusion chromatography and nuclear magnetic resonance spectroscopy. We measured the temperature dependence of the Flory–Huggins interaction parameter (χ) between PVBA and PS as χ = 0.3847 + 55.763/T. The χ was very large (∼0.5 at 200 °C). The phase behavior of PVBA-b-PS with various volume fractions of PS block (fPS) was investigated via small-angle X-ray scattering and transmission electron microscopy. With increasing fPS from 0.1 to 0.8, body-centered-cubic spheres of PS, hexagonally...