Entropy-driven phase behaviour of all-DNA associative polymers
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866915496401567744 |
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| author | Guerra, Francesco Tosti Marini, Federico Sciortino, Francesco Rovigatti, Lorenzo |
| author_facet | Guerra, Francesco Tosti Marini, Federico Sciortino, Francesco Rovigatti, Lorenzo |
| contents | Associative polymers (APs) with reversible, specific interactions between ``sticker'' sites exhibit a phase behavior that depends on a delicate balance between distinct contributions controlling the binding. For highly-bonded systems, it is entropy that mostly determines if, on increasing concentration, the network forms progressively or \textit{via} a first-order transition. With the aim of introducing an experimentally-viable system tailored to test the subtle dependence of the phase behavior on the binding site topology, here we numerically investigate AP polymers made of DNA, where ``sticker'' sites made by short DNA sequences are interspersed in a flexible backbone of poly-T spacers. Due to their self-complementarity, each binding sequence can associate with another identical sticky sequence. We compare two architectures: one with a single sticker type, $(AA)_6$, and one with two distinct alternating types, $(AB)_6$. At low temperature, when most of the stickers are involved in a bond, the $(AA)_6$ system remains homogeneous, while the $(AB)_6$ system exhibits phase separation, driven primarily by entropic factors, mirroring predictions from simpler bead-spring models. Analysis of bond distributions and polymer conformations confirms that the predominantly entropic driving force behind this separation arises from the different topological constraints associated with intra- versus inter-molecular bonding. Our results establish DNA APs as a controllable, realistic platform for studying in the laboratory how the thermodynamics of associative polymer networks depends on the bonding site architecture in a clean and controlled way. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_04482 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Entropy-driven phase behaviour of all-DNA associative polymers Guerra, Francesco Tosti Marini, Federico Sciortino, Francesco Rovigatti, Lorenzo Soft Condensed Matter Associative polymers (APs) with reversible, specific interactions between ``sticker'' sites exhibit a phase behavior that depends on a delicate balance between distinct contributions controlling the binding. For highly-bonded systems, it is entropy that mostly determines if, on increasing concentration, the network forms progressively or \textit{via} a first-order transition. With the aim of introducing an experimentally-viable system tailored to test the subtle dependence of the phase behavior on the binding site topology, here we numerically investigate AP polymers made of DNA, where ``sticker'' sites made by short DNA sequences are interspersed in a flexible backbone of poly-T spacers. Due to their self-complementarity, each binding sequence can associate with another identical sticky sequence. We compare two architectures: one with a single sticker type, $(AA)_6$, and one with two distinct alternating types, $(AB)_6$. At low temperature, when most of the stickers are involved in a bond, the $(AA)_6$ system remains homogeneous, while the $(AB)_6$ system exhibits phase separation, driven primarily by entropic factors, mirroring predictions from simpler bead-spring models. Analysis of bond distributions and polymer conformations confirms that the predominantly entropic driving force behind this separation arises from the different topological constraints associated with intra- versus inter-molecular bonding. Our results establish DNA APs as a controllable, realistic platform for studying in the laboratory how the thermodynamics of associative polymer networks depends on the bonding site architecture in a clean and controlled way. |
| title | Entropy-driven phase behaviour of all-DNA associative polymers |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2505.04482 |