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Polymer network-induced ordering in a nematogenic liquid: a Monte Carlo study
C Chiccoli1, P Pasini, G Skacej
1INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna, Italy.
Summary
This study explores how polymer networks affect liquid crystal alignment. Increasing disorder in anchoring conditions reduces the network's ability to align the liquid crystal, but alignment is retained unless anchoring is completely random.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Nematic liquid crystals exhibit molecular ordering.
- Dispersed polymer networks can influence liquid crystal alignment.
- Surface morphology and anchoring conditions are critical factors.
Purpose of the Study:
- To investigate molecular ordering in liquid crystals with dispersed polymer networks.
- To analyze the impact of surface roughness and anchoring disorder on alignment.
- To determine the conditions under which a polymer network loses its aligning capability.
Main Methods:
- Monte Carlo simulations were employed.
- Order parameters were calculated to quantify molecular ordering.
- 2H nuclear magnetic resonance (NMR) spectra were used for analysis.
Main Results:
- The aligning capability of the polymer network diminishes with increased anchoring disorder.
- Complete loss of alignment occurs only under completely disordered anchoring conditions.
- Surface-induced paranematic order is observed above the nematic-isotropic transition temperature.
- Topological line defects are present with smooth fiber surfaces and homeotropic anchoring.
Conclusions:
- Polymer network structure and surface anchoring significantly control liquid crystal molecular ordering.
- Partial disorder in anchoring does not necessarily abolish the aligning effect.
- Specific conditions can lead to the formation of topological defects.