English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We consider orientational transitions of lamellar phases under the influenceof a spatially nonuniform electric field. The transition between parallel andperpendicular lamellar stackings with respect to the substrate is investigatedas a function of the system parameters. The dielectrophoretic energy and theenergy penalty for having dielectric interfaces perpendicular to the field'sdirection are identified as linear and quadratic terms in a free energyexpansion in the dielectric constant mismatch. We find that if the dielectricconstant mismatch $\Delta\eps$ is smaller than some critical value$\Delta\eps_c$, parallel lamellar stacking will be realized, no matter howlarge the voltage difference between electrodes is. At$\Delta\eps>\Delta\eps_c$, perpendicular stacking will appear if the voltage ishigh enough. Nonuniform fields remove the in-plane degeneracy present in themore common uniform fields. We therefore calculate the energy of grains ofdifferent orientations. The torque acting on the grains leads to the preferenceof only one orientation. The results have direct implications to blockcopolymer orientation and to surface patterning on the nanometer scale.Comment: 5 pages, 7 figure

Lamellar Phases in Nonuniform Electric Fields: Breaking the In-Plane Rotation Symmetry and the Role of Dielectric Constant Mismatch