Polymer Centre research highlight – April 2012Posted on Thursday, April 19th, 2012 in News, Publications| Share this article
University of Sheffield materials scientists, Dr Xiang-bing Zeng and Prof Goran Ungar, have reported the results of research to design a group of liquid crystal materials which could potentially be exploited as new electrolytes in batteries, selectively permeable membranes (or nanofiltration) and in drug delivery.
Bicontinuous cubic phases are a group of nanostructured liquid-crystalline phases having three-dimensionally interconnected nanochannels. Since the channel structures of these materials possess well-defined sizes and shapes, there are great expectations for their application in systems that require selective permeation of materials. The advantage of the 3-d ion channel networks over 1-d straight channels of the columnar phase or 2-d layers of lamellar phases is that the 3-d channel networks do not require alignment and that broken channels self-heal and reconnect – there are no domain boundaries.
The work involved the preparation of wedge-shaped ammonium and phosphonium salts, with 3,4,5-tris(alkyloxy)benzyl moieties. The materials exhibit thermotropic bicontinuous cubic and hexagonal columnar liquid-crystalline phases by nanosegregation between ionophilic and ionophobic parts. The alkyl chain lengths on the cationic moieties, anion species, and alkyl chain lengths on the benzyl moieties have crucial effects on their thermotropic phase behavior. Synchrotron diffraction convincingly showed that the structure is composed of three-dimensionally interconnected ion nanochannel networks surrounded by aliphatic domains. As an example of how these materials could be useful in battery applications, the LC onium salts dissolve lithium tetrafluoroborate without losing their nanostructure.
Original Publication: Induction of Thermotropic Bicontinuous Cubic Phases in Liquid-Crystalline Ammonium and Phosphonium Salts. Takahiro Ichikawa, Masafumi Yoshio, Atsushi Hamasaki, Satomi Taguchi, Feng Liu, Xiang-bing Zeng, Goran Ungar, Hiroyuki Ohno, and Takashi Kato. Journal of the American Chemical Society, 2012, 134 (5), pp 2634–2643.
For more information, please contact Dr Joe Gaunt at the Polymer Centre.