Effects of spatially-varying substrate anchoring on instabilities and dewetting of thin nematic liquid crystal films

Abstract

Partially wetting nematic liquid crystal (NLC) films on substrates are unstable to dewetting-type instabilities due to destablizing solid/NLC interaction forces. These instabilities are modified by the nematic nature of the...

Young and Young–Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

“…Many experimental studies have considered delicate balances between a number of these effects in different situations; for instance, close to the isotropicnematic phase transition [13,24,25], near to a contact line [26][27][28] or in the presence of an external electromagnetic field [29][30][31]. There has also been recent interest in nematic films on substrates with patterned anchoring [8,32] and systems with an isotropic liquid-nematic interface, such as nematic tactoids [33]. Since in the present work we consider length scales greater than a nanometre scale, it is appropriate to neglect van der Waals forces [15], and we consider only uniform anchoring and the competition between elastic forces, alignment forces on the interfaces and gravity.…”

“…The theoretical study of nematic systems that include contact lines often avoids the consideration of antagonistic anchoring at the contact lines, by, for example, imposing infinite anchoring on the nematic–substrate interface, which overrides the weak anchoring on the gas–nematic interface at the contact line (e.g. [8,9]), or assuming the existence of a thin precursor film on the substrate to remove the contact line entirely (e.g. [11]).…”

“…These devices often involve liquid crystal droplets or films, which are complicated multiphase systems that involve interfaces between the liquid crystal, a solid substrate and a passive gas, and often include liquid crystalsubstrate-gas three-phase contact lines. Theoretical studies of liquid crystal droplets or films often use theories of wetting and dewetting for isotropic droplets and films which do not account for the full anisotropic nature of liquid crystals [7][8][9][10][11][12][13][14].…”

Young and Young--Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

“…The theoretical study of nematic systems that include contact lines often avoids the consideration of antagonistic anchoring at the contact lines, by, for example, imposing infinite anchoring on the nematic-substrate interface which overrides the weak anchoring on the gas-nematic interface at the contact line (see, for example, Lam et al [8,9]), or assuming the existence of a thin precursor film on the substrate to remove the contact line entirely (see, for example, Lin et al [11]). While there have been relatively few studies of nematic contact lines, Rey [36,37] considered two rather specific two-dimensional scenarios, namely either infinite planar anchoring or equal weak planar anchoring, on both interfaces.…”

“…Theoretical studies of liquid crystal droplets or films often use theories of wetting and dewetting for isotropic droplets and films which do not account for the full anisotropic nature of liquid crystals [7][8][9][10][11][12][13][14].…”