Phase Behavior of Adenine-Containing Block Copolymer

Abstract

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 (f PS) was investigated via small-angle X-ray scattering and transmission electron microscopy. With increasing f PS from 0.1 to 0.8, body-centered-cubic spheres of PS, hexagonally packed (HEX) cylinders of PS, lamellae, and HEX cylinders of PVBA were observed. Interestingly, PVBA-b-PS with f PS = 0.75 showed asymmetric lamellar microdomains. We also prepared a thin film of PVBA-b-PS on a substrate as a template for spatial arrangement of gold nanoparticles (AuNPs). When the surface of AuNPs was modified with thymine-containing polymer chains, AuNPs were selectively sequestered into PVBA microdomains through the complementary hydrogen bonding between thymine and adenine units.

Nucleobase-Containing Block Copolymers Having a High Interaction Parameter by Complementary Hydrogen Bonding

“…VBA and VBT monomers were synthesized according to the literature. ,, Styrene (Aldrich Chem., ≥99%) was purified using vacuum distillation over calcium hydride and the inhibitor in styrene was removed by passing through an activated alumina oxide column. 2-Cyano-2-propyl benzodithioate (CPBdT, Aldrich Chem., 97%) as a chain transfer agent (CTA) was used without further purification.…”

“…19,20 Previously, we reported that with increasing the volume fraction of the PS block (f PS ) in PVBAb-PS, body-centered cubic spheres of PS, hexagonally packed (HEX) cylinders of PS, lamellae, and HEX cylinders of PVBA were formed. 21 Also, χ between PS and PVBA was high (0.5 at 200 °C) due to hydrophobic PS and hydrophilic PVBA. 21 However, to improve further the sensing and catalytic performance, a high-density array of nanopatterns consisting of nucleobase-containing blocks having a smaller feature size is needed.…”

“…21 Also, χ between PS and PVBA was high (0.5 at 200 °C) due to hydrophobic PS and hydrophilic PVBA. 21 However, to improve further the sensing and catalytic performance, a high-density array of nanopatterns consisting of nucleobase-containing blocks having a smaller feature size is needed. This would be achieved by increasing further χ between PS and a nucleobase-containing block.…”

“…O’Reilly and co-workers synthesized a polystyrene (PS)- b -PVBA copolymer by templating polymerization of poly­[1-(4-vinylbenzyl)­thymine] (PVBT) . Long and co-workers reported that the PVBA- b -poly­( n -butyl acrylate)- b -PVBA triblock copolymer showed phase transition from cylindrical to lamellar microdomains by blending of uracil-containing phosphonium salt. , Previously, we reported that with increasing the volume fraction of the PS block ( f PS ) in PVBA- b -PS, body-centered cubic spheres of PS, hexagonally packed (HEX) cylinders of PS, lamellae, and HEX cylinders of PVBA were formed . Also, χ between PS and PVBA was high (0.5 at 200 °C) due to hydrophobic PS and hydrophilic PVBA …”

Nucleobase-containing polymer architectures controlled by supramolecular interactions: the key to achieve biomimetic platforms with various morphologies

“…6, A). 33,34 Furthermore, multiblock amphiphilic copolymers were designed by the sequential RAFT polymerization of thymine acrylate, n-butyl acrylate, and Please do not adjust margins Please do not adjust margins adenine acrylate using a bifunctional macro-CTA agent (Fig. 6, B).…”