Liquid Crstal

Queen's University in Canada Selects Linkam Temperature Stages to Characterize Ferroelectric Liquid Crystals


image sourced from Prof Lemieux's Group at Queen's University
Market leaders in temperature controlled microscopy, Linkam Scientific Instruments, have been used as temperature stage suppliers to Queen's University in Canada for ten years to study the properties of ferroelectric liquid crystals.
The research program of Professor Robert Lemieux and his Kingston, Ontario- based team focuses on the rational design of chiral and achiral molecular components of ferroelectric liquid crystal mixtures based on principles of self-assembly and molecular recognition.
Understanding the thermal properties of liquid crystals is crucial to the establishment of structure-property relationships that are useful in the design of new materials with improved properties. For example, in the design of 'de Vries-like' liquid crystals, the focus is on changes occurring at the SmA-SmC phase transition, both in terms of the order of the phase transition as well as changes in physical properties such as birefringence. As such, the use of thermal polarized optical microscopy allows the observation of texture changes at the SmA-SmC phase transition that provides useful information on such changes, and the Linkam LTS-350 hot stage used provides precise temperature control for this purpose.
The design of the LTS-350 hot stage also makes possible the integration of thermal polarized optical microscopy with the automated Liquid Crystal Analysis System (LCAS-1) by LC Vision in a convenient, turn-key fashion. This is used to measure the spontaneous polarization and optical tilt angle of ferroelectric SmC* liquid crystals induced by a variety of chiral dopants. These measurements are normally performed as a function of temperature using the LTS-350 hot stage.
The Linkam Liquid Crystal Pro system is in use by scientists all over the world. Leading academic and industrial research scientists have made the LTSE350 their preferred choice because of the high degree of control of heating rates, accuracy and long term stability for temperature controlled studies using light microscopes and other spectrometer platforms. It is optimised for liquid crystal sample analysis having fast heating rates up to 30°C/min and excellent thermal stability over the range from -196°C to 350°C. The stage consists of a large area temperature controlled element with a 100 Ohm platinum resistor sensor embedded close to the surface for accurate temperature measurements. It may be operated with Linksys32 DV Imaging software and a QICAM digital camera to provide fully indexed images at predefined points in the temperature profile. For a completely integrated solution, the system can be used with the Linkam Imaging Station to provide an ergonomic platform for easy sample handling without the need for a stand-alone optical microscope.

 

content originally posted at Nanowerk

Hanging out with the Liquid Crystal Elite

 

This week, Linkam is attending the 23rd International Liquid Crystal conference in Krakow along with 650 of the world’s top liquid crystal scientists. 
With over 180 oral presentations and 1000 posters, the show covered numerous new developments with ferroelectric LC’s including work on nanoparticles, traditional nematic materials and some blue phase work. 
Many delegates are existing Linkam users and have provided really positive feedback about our products as well as a host of ideas for future instrument developments.
 Linkam is exhibiting with LC-Vision from Boulder, Colorado, highlighting the integration possibilities between the LCAS-3 system and the Linkam LTSE350 hot stage. 
A complete system enables accurate temperature control with image capture to be combined with a range of electrical measurements, including the elastic constants K11, K22, K33  rotational viscosity and dielectric properties (parallel and perpendicular). 
Thanks to all those who visited our booth and a special thanks to Monika Marzec whose organisation made the exhibition run so smoothly.

 

Hours of Liquid Crystal Analysis- Done in Minutes

 

Michael Jordan is arguably the greatest basketball player to ever set foot on the basketball court.  He probably knows this, he has 6 NBA championship rings.  However, an actor, he is not. did you ever see Space Jam?  Nope, not too many did.

 

It's a good idea to stick with what you're best at.

We make temperature controlled stages for a variety of microscopy techniques.  This is what we are best at, and so when it comes to analysing liquid crystals, we'll take care of the temperature control microscopy instruments, but we'll turn over the in depth quantitative analysis to the experts.

We will be working with Dr. Michael Wand and the folks at LC-Vision to promote their LCAS range of liquid crystal analysis instruments.  The LCAS range utilise an LC cell holder that will fit into our LTS120 and LTS420 temperature controlled stages to enable the user to analyze liquid crystals in minutes that would otherwise take hours.

Property analysis of nematic LC includes:
 

  • Threshold voltage (Vth) • Parallel dielectric (Epara)
  • Perpendicular dielectric (Eperp)
  • Dielectric anisotropy (ΔE)
  • Splay elastic Constant (K1)
  • Bend elastic constant (K3)
  • Rotational viscosity
  • Ionic density – both positive and negative ions
  • Will measure negative ΔE nematic liquid crystals using high to low voltage sweep)
Further details available at LC-vision.com