Next Article in Journal
Synthesis, Structural Studies, and Anticancer Properties of [CuBr(PPh3)2(4,6-Dimethyl-2-Thiopyrimidine-κS]
Next Article in Special Issue
Induced Smectic Phases from Supramolecular H-Bonded Complexes Based on Non-Mesomorphic Components
Previous Article in Journal
Wafer-Scale Semipolar Micro-Pyramid Lighting-Emitting Diode Array
Previous Article in Special Issue
Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal
Article

Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals

Experimental Soft Matter Physics Group, University of Luxembourg, L-1511 Luxembourg, Luxembourg
*
Authors to whom correspondence should be addressed.
Current address: Laboratory of Physical Chemistry and Soft Matter, Wageningen University and Research, 6708 WE Wageningen, The Netherlands.
Academic Editors: Sergey Shvetsov and Hoda A. Ahmed
Crystals 2021, 11(6), 687; https://doi.org/10.3390/cryst11060687
Received: 21 May 2021 / Revised: 8 June 2021 / Accepted: 11 June 2021 / Published: 15 June 2021
(This article belongs to the Special Issue Optical and Molecular Aspects of Liquid Crystals)
Liquid crystal (LC) phases typically show anisotropic alignment-dependent properties, such as viscosity and dielectric permittivity, so it stands to reason that LCs also have anisotropic interfacial tensions. Measuring the interfacial tension γ of an LC with conventional methods, such as pendant drops, can be challenging, however, especially when we need to know γ for different LC aligning conditions, as is the case when we seek Δγ, the interfacial tension anisotropy. Here, we present measurements of Δγ of the common synthetic nematic LC compound 5CB against water using a microfluidic droplet aspiration technique. To ensure tangential and normal alignment, respectively, we add poly(vinyl alcohol) (PVA) and sodium dodecylsulfate (SDS), respectively, as a stabilizer and measure γ for different concentrations of stabilizer. By fitting the Szyszkowski equation to the data, we can extrapolate to zero-stabilizer concentration, obtaining the γ of 5CB to pure water for each alignment. For normal alignment, we find γ=31.9±0.8 mN·m−1, on the order of 1 mN·m−1 greater than γ||=30.8±5 mN·m1 for tangential alignment. This resonates with the empirical knowledge that 5CB aligns tangentially to an interface with pure water. The main uncertainty arises from the use of polymeric PVA as tangential-promoting stabilizer. Future improvements in accuracy may be expected if PVA can be replaced by a low molar mass stabilizer that ensures tangential alignment. View Full-Text
Keywords: liquid crystal; interfacial tension; surface tension; alignment; anisotropy; PVA; SDS; microfluidics liquid crystal; interfacial tension; surface tension; alignment; anisotropy; PVA; SDS; microfluidics
Show Figures

Figure 1

MDPI and ACS Style

Honaker, L.W.; Sharma, A.; Schanen, A.; Lagerwall, J.P.F. Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals. Crystals 2021, 11, 687. https://doi.org/10.3390/cryst11060687

AMA Style

Honaker LW, Sharma A, Schanen A, Lagerwall JPF. Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals. Crystals. 2021; 11(6):687. https://doi.org/10.3390/cryst11060687

Chicago/Turabian Style

Honaker, Lawrence W., Anjali Sharma, Andy Schanen, and Jan P.F. Lagerwall 2021. "Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals" Crystals 11, no. 6: 687. https://doi.org/10.3390/cryst11060687

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop