Prenematic Fluctuations in Nanoparticle-Hosted Systems

Fuente: arXiv
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Autori principali: Starzonek, Szymon, Górny, Krzysztof, Dendzik, Zbigniew, Črešnar, Dejvid, Iglič, Aleš
Natura: Preprint
Pubblicazione: 2025
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author Starzonek, Szymon
Górny, Krzysztof
Dendzik, Zbigniew
Črešnar, Dejvid
Iglič, Aleš
author_facet Starzonek, Szymon
Górny, Krzysztof
Dendzik, Zbigniew
Črešnar, Dejvid
Iglič, Aleš
contents This study combines broadband dielectric spectroscopy (BDS) experiments with molecular dynamics (MD) simulations to investigate the influence of nanoparticle (NP) inclusions on pretransitional phenomena in a liquid crystal (LC) host. We aimed to fill the existing gap between macroscopic observations and their microscopic origins. Our experimental results on SiO$_2$-doped 5CB composites demonstrate that while NP additions do not significantly change the isotropic-nematic transition temperature ($T_c$), the pretransitional effects exhibit universal behavior, confirmed by identical critical exponents across all samples. The observed systematic decrease in dielectric permittivity is explained by MD simulations, which reveal that nanoparticles act as "seeds" for topological defects, forcing the surrounding LC molecules into a "hedgehog" configuration. This static, defect-induced structure leads to a local antiparallel alignment and cancellation of molecular dipoles, providing a direct microscopic mechanism for the macroscopic dielectric response and successfully bridging the micro-macro scales.
format Preprint
id arxiv_https___arxiv_org_abs_2507_01562
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Prenematic Fluctuations in Nanoparticle-Hosted Systems
Starzonek, Szymon
Górny, Krzysztof
Dendzik, Zbigniew
Črešnar, Dejvid
Iglič, Aleš
Soft Condensed Matter
This study combines broadband dielectric spectroscopy (BDS) experiments with molecular dynamics (MD) simulations to investigate the influence of nanoparticle (NP) inclusions on pretransitional phenomena in a liquid crystal (LC) host. We aimed to fill the existing gap between macroscopic observations and their microscopic origins. Our experimental results on SiO$_2$-doped 5CB composites demonstrate that while NP additions do not significantly change the isotropic-nematic transition temperature ($T_c$), the pretransitional effects exhibit universal behavior, confirmed by identical critical exponents across all samples. The observed systematic decrease in dielectric permittivity is explained by MD simulations, which reveal that nanoparticles act as "seeds" for topological defects, forcing the surrounding LC molecules into a "hedgehog" configuration. This static, defect-induced structure leads to a local antiparallel alignment and cancellation of molecular dipoles, providing a direct microscopic mechanism for the macroscopic dielectric response and successfully bridging the micro-macro scales.
title Prenematic Fluctuations in Nanoparticle-Hosted Systems
topic Soft Condensed Matter
url https://arxiv.org/abs/2507.01562