Complex Smectic Phases in Polymer Grafted Shape-Uniform Cellulose Nano-Crystals

Fuente: arXiv
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Autori principali: Fall, William S., Wensink, Henricus H.
Natura: Preprint
Pubblicazione: 2024
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author Fall, William S.
Wensink, Henricus H.
author_facet Fall, William S.
Wensink, Henricus H.
contents The effect of short chain grafting on the liquid crystalline (LC) ordering of nano-crystals is investigated using molecular dynamics simulations of a coarse-grained grafted nano-rod model. Monodisperse nano-rods, with aspect ratios typical of cellulose nano-crystals (CNCs) are grafted randomly with oligomers at different grafting densities. LC ordering depends non-trivially on grafting density as the effective nano-rod shape and softness is modified. Ungrafted rods exhibit Nematic and tilted Smectic-C phases. At 25\% grafting, the addition of a few side chains entirely suppresses Smectic order and instead a persistent Nematic phase is favoured. Intermediary grafting, around 50\%, results in a Nematic and the reappearance of tilted Smectic-F phases. Heavier grafting facilitates direct transitions to either Smectic-I with extreme tilt (75\%) or an un-tilted Smectic-B (100\%). Such behaviour falls outside of current hard or soft-rod descriptions of phase-transitions in rod-like LC systems and points to undiscovered LC behaviour in both shape-purified grafted/un-grafted CNCs.
format Preprint
id arxiv_https___arxiv_org_abs_2407_05401
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Complex Smectic Phases in Polymer Grafted Shape-Uniform Cellulose Nano-Crystals
Fall, William S.
Wensink, Henricus H.
Soft Condensed Matter
Materials Science
The effect of short chain grafting on the liquid crystalline (LC) ordering of nano-crystals is investigated using molecular dynamics simulations of a coarse-grained grafted nano-rod model. Monodisperse nano-rods, with aspect ratios typical of cellulose nano-crystals (CNCs) are grafted randomly with oligomers at different grafting densities. LC ordering depends non-trivially on grafting density as the effective nano-rod shape and softness is modified. Ungrafted rods exhibit Nematic and tilted Smectic-C phases. At 25\% grafting, the addition of a few side chains entirely suppresses Smectic order and instead a persistent Nematic phase is favoured. Intermediary grafting, around 50\%, results in a Nematic and the reappearance of tilted Smectic-F phases. Heavier grafting facilitates direct transitions to either Smectic-I with extreme tilt (75\%) or an un-tilted Smectic-B (100\%). Such behaviour falls outside of current hard or soft-rod descriptions of phase-transitions in rod-like LC systems and points to undiscovered LC behaviour in both shape-purified grafted/un-grafted CNCs.
title Complex Smectic Phases in Polymer Grafted Shape-Uniform Cellulose Nano-Crystals
topic Soft Condensed Matter
Materials Science
url https://arxiv.org/abs/2407.05401