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Polymer Functionalized Nanoparticles in Blue Phase LC: Effect of Particle Shape
Manlin Zhang1, Michael Lindner-D'Addario1, Mahdi Roohnikan1
1Centre Québécois sur les Matériaux Fonctionnels/Quebec Centre for Advanced Materials (CQMF/QCAM), Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada.
Nanomaterials (Basel, Switzerland)
|January 11, 2022
Summary
Ethylene oxide ligands on gold nanoparticles affect blue phase liquid crystals. While nanospheres destabilized the phase, nanorods widened the blue phase range, especially with higher molecular weight ligands.
Area of Science:
- Materials Science
- Nanotechnology
- Liquid Crystals
Background:
- Blue phase liquid crystals (BPLC) exhibit unique optical properties.
- Controlling BPLC stability and temperature range is crucial for applications.
- Functionalized nanoparticles offer a route to tune BPLC behavior.
Purpose of the Study:
- To investigate the impact of ethylene oxide ligands, free and tethered to gold nanoparticles (AuNPs and AuNRs), on the blue phase range of liquid crystals.
- To understand the influence of ligand molecular weight and nanoparticle shape on BPLC stability.
- To explore the potential of functionalized nanoparticles for tuning BPLC properties.
Main Methods:
- Synthesis and functionalization of gold nanospheres (AuNPs) and nanorods (AuNRs) with thiolated ethylene oxide ligands of varying molecular weights (200-5000 g/mol).
- Dispersion of functionalized nanoparticles and free ligands in a blue phase liquid crystal mixture.
- Characterization of the blue phase temperature range (ΔTBP) using differential scanning calorimetry and optical microscopy.
Main Results:
- Low molecular weight ethylene oxide oligomers widened the BPLC range, but AuNPs functionalized with these ligands had minimal effect.
- Higher concentrations or molecular weights of free or AuNP-tethered ligands destabilized the BPLC.
- Mini-AuNRs functionalized with ethylene oxide ligands widened the BPLC range, with longer AuNRs showing a greater effect.
- Unlike AuNPs, AuNRs with higher molecular weight ligands widened the BPLC range, with the lowest MW ligand yielding the largest range (ΔTBP > 13 °C).
Conclusions:
- The shape of gold nanoparticles (spheres vs. rods) and ligand molecular weight significantly influence their effect on BPLC stability and temperature range.
- AuNPs may accumulate at defect sites, while smaller AuNRs can more effectively fill defects, leading to different impacts on the BPLC phase.
- Functionalized nanorods show promise for widening the operational temperature range of blue phase liquid crystals.
