Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals
| Autor: | Lawrence William Honaker, Jan P. F. Lagerwall, Anjali Sharma, Andy Schanen |
|---|---|
| Přispěvatelé: | European Commission - EC [sponsor], Fonds National de la Recherche - FnR [sponsor] |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Vinyl alcohol
Materials science General Chemical Engineering Microfluidics Physics [G04] [Physical chemical mathematical & earth Sciences] microfluidics interfacial tension 02 engineering and technology anisotropy 010402 general chemistry 01 natural sciences Inorganic Chemistry Surface tension Viscosity chemistry.chemical_compound Liquid crystal surface tension General Materials Science liquid crystal Composite material Anisotropy SDS Alignment Crystallography Molar mass Szyszkowski equation alignment 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES chemistry Physique [G04] [Physique chimie mathématiques & sciences de la terre] QD901-999 PVA 0210 nano-technology Interfacial tension |
| Zdroj: | Crystals Volume 11 Issue 6 info:eu-repo/grantAgreement/EC/H2020/648763 Crystals, 11(6) Crystals, Vol 11, Iss 687, p 687 (2021) Crystals 11 (2021) 6 |
| ISSN: | 2073-4352 |
| DOI: | 10.3390/cryst11060687 |
| Popis: | 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·m−1 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. |
| Databáze: | OpenAIRE |
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