Self-assembly of block copolymers affords relatively simple and straightforward access to nanoscale ordered structures for surface lithography and development of high performance membranes. A continuing objective of self-assembly research is the creation of increasingly smaller feature sizes, which is dictated by the degree of polymerization (N). However, in order to compensate for the decrease of N, the chemical incompatability (χ) must increase significantly according to Florry-Huggins theory. Thus, the pursuit of “high χ, low N” block copolymers drives a significant amount of research efforts in the field.<br/><br/>Secondary interactions represent a common strategy to promote chemical incompatibility. Clickable nucleic acids (CNAs) demonstrate sequence specific, strong hydrogen bonding with complementary segments, promising great potential in self-assembly. Two CNA-containing diblock copolymers were synthesized through thiol-ene click chemistry and controlled radical polymerization (Figure 1a) with either a poly(thymine) (T) or poly(adenine) (A) CNA homopolymer block. The blend of these two diblock copolymers self-assembled into lamellar lines on a silica surface. Due to the low degree of polymerization (15 for T and 10 for A), the self-assembly (Figure 1b) achieved feature sizes smaller than 10 nm and 5 nm in AFM. Furthermore, simple dilution of the casting solution results in uniform feature sizes (9 nm) and orientation without any pre-patterned surfaces (Figure 1c). When blending CNA-containing diblock copolymers with single strand DNA, self-assembly occurs only when the complementary nucleic acid is present. Together, CNA-containing block copolymers synergized sub-5 nm self-assembled feature sizes and selective ordering with complementary sequence.

Sub-5 nm self-assembly with sequence specific molecular recognition

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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