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Main Authors: Chelli, Lydia, Perera, Aurélien
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.22936
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author Chelli, Lydia
Perera, Aurélien
author_facet Chelli, Lydia
Perera, Aurélien
contents Binary mixtures of two dimensional, site-based models of alcohols are investigated by computer simulations, with a focus on ideal mixing, local clustering and miscibility trends. Four representative systems are considered: methanol/ethanol, butanol/pentanol, methanol/pentanol, and methanol/octanol. The models retain chemical specificity, while allowing to investigate dimensional constraints and uncover non/trivial micro/structurations. Two unexpected results are observed. First, mixtures of short and long alcohols are well mixed, instead of the macroscopic phase separation found in their three-dimensional counterparts. Second, ideality and micro phase separation compete within the chain like polar head aggregates. These behaviors cannot be explained solely by enhanced fluctuations in two dimensions, and instead point to a key role of charge ordering in shaping the local structure. The resulting interplay between concentration fluctuations and micro heterogeneous aggregation is analyzed through snapshots, site/site distribution functions, structure factors and Kirkwood Buff integrals. In particular, the analysis reveals that the domain correlations in the long range part of the correlations have an intriguing non self averaging behaviour, similar to that found in the real systems, indicating that mixtures of associating molecules are not ruled by conventional fluctuations.
format Preprint
id arxiv_https___arxiv_org_abs_2604_22936
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Charge order, domain order, ideal mixing and absence of demixing in 2D binary mixtures of alcohols
Chelli, Lydia
Perera, Aurélien
Chemical Physics
Binary mixtures of two dimensional, site-based models of alcohols are investigated by computer simulations, with a focus on ideal mixing, local clustering and miscibility trends. Four representative systems are considered: methanol/ethanol, butanol/pentanol, methanol/pentanol, and methanol/octanol. The models retain chemical specificity, while allowing to investigate dimensional constraints and uncover non/trivial micro/structurations. Two unexpected results are observed. First, mixtures of short and long alcohols are well mixed, instead of the macroscopic phase separation found in their three-dimensional counterparts. Second, ideality and micro phase separation compete within the chain like polar head aggregates. These behaviors cannot be explained solely by enhanced fluctuations in two dimensions, and instead point to a key role of charge ordering in shaping the local structure. The resulting interplay between concentration fluctuations and micro heterogeneous aggregation is analyzed through snapshots, site/site distribution functions, structure factors and Kirkwood Buff integrals. In particular, the analysis reveals that the domain correlations in the long range part of the correlations have an intriguing non self averaging behaviour, similar to that found in the real systems, indicating that mixtures of associating molecules are not ruled by conventional fluctuations.
title Charge order, domain order, ideal mixing and absence of demixing in 2D binary mixtures of alcohols
topic Chemical Physics
url https://arxiv.org/abs/2604.22936