Entropy-driven phase behavior of all-DNA associative polymers.

Area of Science:

• Polymer Science
• Supramolecular Chemistry
• Biomaterials Science

Background:

• Associative polymers (APs) feature reversible interactions between specific
• sticker
• sites, influencing their phase behavior.
• The thermodynamics of AP network formation depend on binding contributions, with entropy playing a key role in highly bonded systems.

Purpose of the Study:

• To numerically investigate DNA-based associative polymers as an experimentally viable system.
• To explore how binding site topology affects the phase behavior of associative polymers.
• To compare the phase behavior of APs with single sticker types versus distinct alternating sticker types.

Main Methods:

• Numerical investigation of DNA associative polymers with poly-T spacers.
• Comparison of two architectures: single sticker type (AA)6 and alternating sticker types (AB)6.
• Analysis of bond distributions and polymer conformations at low temperatures.

Main Results:

• The (AA)6 system remains homogeneous at low temperatures, while the (AB)6 system undergoes phase separation.
• Phase separation in the (AB)6 system is primarily driven by entropic factors.
• Different topological constraints in intra- vs. inter-molecular bonding contribute to the entropic driving force.

Conclusions:

• DNA associative polymers provide a controllable platform for studying polymer network thermodynamics.
• Binding site architecture significantly influences the phase behavior of associative polymers.
• The findings align with predictions from simpler models, validating the DNA AP system for experimental studies.