Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Unusual liquid crystal structures on water surface

Jan Paczesny, a PhD student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, presents the roll-over mechanism of liquid crystal layers on the water surface that is responsible for formation of the 9-layer film. (Source: IPC PAS, Grzegorz Krzyżewski)
Jan Paczesny, a PhD student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, presents the roll-over mechanism of liquid crystal layers on the water surface that is responsible for formation of the 9-layer film.

(Source: IPC PAS, Grzegorz Krzyżewski)

Abstract:
Some liquid crystals form monolayers on water surface. When compressed from sides, such films of monomolecular thickness can wrinkle like fabric on a flat, smooth table, pulled together with palms simultaneously from both sides. With increasing surface pressure, the wrinkles of the monolayer fold up and form subsequent layers. The research on new compounds at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw has resulted in the discovery of new mechanisms of multilayer formation that are responsible for creation of liquid crystal films with a structure that has never been observed before.

Unusual liquid crystal structures on water surface

Warsaw, Poland | Posted on November 17th, 2011

After pouring on a water surface, liquid crystals can form ordered layers of monomolecular thickness. When such layers are compressed in their plane, they can form, under appropriate conditions, a film composed of three layers - a trilayer. It was supposed that from time to time even 5-layers may be formed. "The existence of 5-layers has not, however, been well documented. We managed to confirm their presence with high precision. Moreover, we observed 9-layers that until now were considered exclusively as research suggestions", says Dr Andrzej Żywociński from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw. The research findings have been published in "Chemistry - A European Journal".

The researchers from IPC PAS poured microliters of liquid crystals on the surface of water. The compounds and their amounts were adjusted so as to form an ordered monomolecular layer (with a thickness of one molecule). The monolayers can be compressed with an apparatus called Langmuir trough. It is basically a trough with two hydrophilic barriers, between which a monolayer of chemical compound under study is drifting on the water surface. By reducing the distance between the barriers one can significantly increase the pressure in the monolayer plane.

The research pursued by Dr Żywociński and Prof. Robert Hołyst's PhD students was focused on about a dozen compounds from the group of bolaamphiphiles synthesised in Prof. Carsten Tschierske's research team from the Martin-Luther-University of Halle-Wittenberg. The molecules of these compounds have various complicated shapes, sharing a rigid core with hydrophilic (water-loving) groups attached to both ends. These groups anchor the molecule to the water surface. In addition, the central part of the core contains hydrophobic (water-hating) chains. A part of molecules studied had two hydrophobic groups in an X-shaped arrangement, another part - one such group in a T-like configuration, while in the remaining molecules the core was not straight but bent, resembling the shape of an anchor.

In molecules used in the study, hydrogen atoms in hydrophobic chains were partially replaced with fluorine atoms, which resulted in an increased rigidity and hydrophobicity. Due to the substitution, the molecules, especially those X-shaped, formed on water very stable, well ordered monolayers.

The measurements have shown that the molecules of compounds studied behave somewhat like fabric on a table (with one significant difference: a fabric is solid, and the processes described here occur only if the compound is in the liquid phase). When a monolayer is compressed from sides, the forces acting in the system displace the molecules upward, and the monolayer develops folds that subsequently roll over. If the compression is continued, an ordered structure composed of three monolayers is formed on the water surface. The process has already been described in the scientific literature.

"We were able to observe and document a much more interesting mechanism", says Jan Paczesny, a PhD student from the IPC PAS. "It turned out that further compression of a trilayer formed by one of the compounds leads to the folding that involves not one, external monolayer, but the entire trilayer. The fold being pushed out has then a thickness of six layers and after rolling over on a trilayer, our molecular ‘fabric' becomes an excellently ordered 9-layer". An increase of the multilayer thickness in the sequence: mono-, 3- and 9-layer was suggested in the literature, but the mechanism was for the first time confirmed experimentally.

The group from the IPC PAS studied also substances, where the intermolecular interactions were not sufficiently flexible. During compression of such compounds, it is not the monolayer that folds and rolls over, but single molecules are pushed out over the monolayer and after detachment from water surface aggregate in pairs. Being non-volatile, they stay with the monolayer and are ordered with increasing pressure, forming at once two layers on the monolayer. This newly recognised mechanism explains why multilayers increase their thickness in sequence 1-3-5-7 monolayers.

The researchers from the IPC PAS are convinced that processes similar to the both observed ones occur also for other chemical compounds with similar molecular structure.

Practical application of the ordered multilayers is possible after transferring them from the water surface onto a solid substrate, e.g. silicon wafer. To do so, a silicon wafer is repeatedly immersed and removed from a bath consisting of water with a multilayer. Unfortunately, the monolayers of some substances are being washed out during repeated immersions. The researchers from the IPC PAS met such situation for one of the compounds studied. The measurements have shown, however, that the same compound is transferred permanently when a 9-layer is formed. This means not only that a new type of substrates can be produced but also that the time required to form thick multilayers that were previously produced by laborious deposition of up to a few dozen monolayers can be nine-fold reduced.

The cores of molecules studied in the IPC PAS have three condensed aromatic rings. Analogous structures appear in conducting polymers. "We hope that in future the derivatives of the compounds studied by us will find an application in organic electronics. We also plan to make use of the tendency for self-organisation of these molecules to organise other molecules", comments Dr Żywociński.

This press release was prepared thanks to the NOBLESSE grant under the activity "Research potential" of the 7th Framework Programme of the European Union.

####

About Institute of Physical Chemistry of the Polish Academy of Sciences
The Institute of Physical Chemistry of the Polish Academy of Sciences (http://www.ichf.edu.pl/) was established in 1955 as one of the first chemical institutes of the PAS. The Institute's scientific profile is strongly related to the newest global trends in the development of physical chemistry and chemical physics. Scientific research is conducted in nine scientific departments. CHEMIPAN R&D Laboratories, operating as part of the Institute, implement, produce and commercialise specialist chemicals to be used, in particular, in agriculture and pharmaceutical industry. The Institute publishes approximately 200 original research papers annually.

For more information, please click here

Contacts:
Andrzej Żywociński, PhD, Eng
Institute of Physical Chemistry of the Polish Academy of Sciences
tel. +48 22 3433247
email:

Antoni Szafranski
+48 22 343 3262

Copyright © AlphaGalileo

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Press releases of the Institute of Physical Chemistry of the PAS:

Related News Press

News and information

Nano Ruffles in Brain Matter: Freiburg researchers decipher the role of nanostructures around brain cells in central nervous system function October 31st, 2014

Gold nanoparticle chains confine light to the nanoscale October 31st, 2014

'Nanomotor lithography' answers call for affordable, simpler device manufacturing October 31st, 2014

Device invented at Johns Hopkins provides up-close look at cancer on the move: Microscopic view of metastasis could give insight about how to keep cancer in check October 31st, 2014

Amorphous Coordination Polymer Particles as alternative to classical nanoplatforms for nanomedicine October 30th, 2014

Chemistry

First Observation of Electronic Structure in Ag-Rh Alloy Nanoparticles Having Hydrogen Absorbing: Storage Property –Attempting to solve the mystery of why Ag-Rh alloy nanoparticles have a similar property to Pd– October 30th, 2014

A new cheap and efficient method to improve SERS, an ultra-sensitive chemical detection technique October 28th, 2014

Iranian, Malaysian Scientists Study Nanophotocatalysts for Water Purification October 23rd, 2014

Could I squeeze by you? Ames Laboratory scientists model molecular movement within narrow channels of mesoporous nanoparticles October 21st, 2014

Non-Toxic Nanocatalysts Open New Window for Significant Decrease in Reaction Process October 19th, 2014

Physics

Sussex physicists find simple solution for quantum technology challenge October 28th, 2014

New evidence for an exotic, predicted superconducting state October 27th, 2014

Display technology/LEDs/SS Lighting/OLEDs

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

QD Vision Wins Prestigious Presidential Green Chemistry Challenge Award from the U.S. Environmental Protection Agency October 16th, 2014

Self Assembly

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

‘Designer’ nanodevice could improve treatment options for cancer sufferers October 22nd, 2014

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Discoveries

Nano Ruffles in Brain Matter: Freiburg researchers decipher the role of nanostructures around brain cells in central nervous system function October 31st, 2014

Gold nanoparticle chains confine light to the nanoscale October 31st, 2014

'Nanomotor lithography' answers call for affordable, simpler device manufacturing October 31st, 2014

Device invented at Johns Hopkins provides up-close look at cancer on the move: Microscopic view of metastasis could give insight about how to keep cancer in check October 31st, 2014

Announcements

Nano Ruffles in Brain Matter: Freiburg researchers decipher the role of nanostructures around brain cells in central nervous system function October 31st, 2014

Gold nanoparticle chains confine light to the nanoscale October 31st, 2014

'Nanomotor lithography' answers call for affordable, simpler device manufacturing October 31st, 2014

Device invented at Johns Hopkins provides up-close look at cancer on the move: Microscopic view of metastasis could give insight about how to keep cancer in check October 31st, 2014

NanoNews-Digest
The latest news from around the world, FREE





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE