Magnetically Actuated Liquid Crystals

Abstract

Ferrimagnetic inorganic nanorods have been used as building blocks to construct liquid crystals with optical properties that can be instantly and reversibly controlled by manipulating the nanorod orientation using considerably weak external magnetic fields (1 mT). Under an alternating magnetic field, they exhibit an optical switching frequency above 100 Hz, which is comparable to the performance of commercial liquid crystals based on electrical switching. By combining magnetic alignment and lithography processes, it is also possible to create patterns of different polarizations in a thin composite film and control over the transmittance of light in particular areas. Developing such magnetically responsive liquid crystals opens the door toward various applications, which may benefit from the instantaneous and contactless nature of magnetic manipulation.

Industry & applications news

“…The LCs that have been developed at the Yin Lab are an aqueous dispersion of magnetic iron oxide nanorods [4]. The molecular orientation of these nanorods can be manipulated by a weak magnetic field, with the nanorods aligning themselves along the field direction.…”

Hybrid magnetic iron oxide nanoparticles with tunable field-directed self-assembly

“…[23][24][25][26][27][28] Although the literature is replete with reports on the fieldresponsive behaviour of spherical magnetic particles, [29][30][31][32][33] selfassembly of anisotropic hybrid nanoparticles is a comparatively lesser explored avenue till date. 2,34,35 Ding and co-workers have studied the field driven self-assembly of magnetic ellipsoids into photonic crystals. 36,37 Their approach was limited to ellipsoids with aspect ratios close to that of a sphere which explains the formation of a distorted FCC crystal and hence the photonic behaviour.…”

New liquid crystals derived from thiophene connected to the 1,2,4-oxadiazole heterocycle

“…Over the past few decades liquid crystals (LCs) have received special attention due to the possibility of reorientation with electric and magnetic fields [1,2], which allows control of their self-organising ability [3][4][5]. Thus, these materials have become good candidates for technologic application in electro-optic displays, in solar cells [6], as sensors [7], for high-density memory storage [8] and in light-emitting diodes (OLEDs) [9].…”

“…A beige solid (1.1 g, 84%) was obtained by recrystallisation in CHCl 3 . Mp: Cr -184°C -N -189°C -I. IR (KBr pellet) ν max cm −1 : 3091,2921, 2852, 1607,1576 1. H NMR (400 MHz, CDCl 3 ), δ, ppm: 8.16 (d, J = 8.9 Hz, 4H, Ar-H), 7.90 (s, 2H, Ar-H), 7.05 (d, J = 8.9 Hz, 4H, Ar-H), 4.06 (m, 4H, -OCH 2 -), 1.84 (m, 4H, -CH 2 -), 1.49 (m, 4H, -CH 2 -), 1.28 (m, 24H, -CH 2 -), 0.89 (t, J = 6.8 Hz, 6H, -CH 3 ).…”