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A new series of siloxane liquid crystalline dimers exhibiting the antiferroelectric phase

Nils Olsson ; Bertil Helgee (Institutionen för kemi- och bioteknik, Polymerteknologi ; Institutionen för fysik (GU)) ; Gunnar Andersson ; Lachezar Komitov
Liquid Crystals (0267-8292). Vol. 32 (2005), 9, p. 1139-1150.
[Artikel, refereegranskad vetenskaplig]

In this paper, we report the study of a new series of symmetric chiral liquid crystalline siloxane dimers, their related monomers, and two of those monomers with heptamethyltrisiloxane attached. All the dimers coupled with a trisiloxane show the SmCA phase, which in several cases has a large tilt angle greater than 40° over a wide temperature range, as well as high spontaneous polarisation in the field-induced ferroelectric state. Spacer lengths of 3-6 and 11 carbons between the siloxane central unit and the mesogenic cores were used. Monomers with 3-6 carbons in the spacer showed only orthogonal phases while the monomer with an 11-carbon spacer, as well as the monomers with siloxane attached, have a high tilt angle ferroelectric phase. The materials were characterized by means of DSC, NMR, X-ray diffraction, electro-optical methods (tilt angle and texture characterization) and polarization measurements.

Nyckelord: siloxane, liquid crystals, dimers, antiferroelectric, ferroelectric, tilt angle



Denna post skapades 2007-11-07.
CPL Pubid: 61331

 

Institutioner (Chalmers)

Institutionen för fysik (GU) (GU)
Institutionen för kemi- och bioteknik, Polymerteknologi (2005-2014)

Ämnesområden

Optik
Organisk syntes
Polymerkemi

Chalmers infrastruktur