The THMS600 heating stage is being used for liquid crystal research at the University of the Free State in South Africa.
Researchers in the physical chemistry department of the University of the Orange Free State (UFS) have examined the discotic liquid crystal properties of a number of long chain metal free and zinc phthalocyanines using the Linkam THMS600 hot stage.
Phthalocyanines are aromatic compounds, with a variable length carbon chain, produced when the phthalocyanine molecule reacts with metals to form brightly colored complexes.
The samples were studied using the THMS600 stage in conjunction with an Olympus BH-2 polarising microscope.
The scientists were able to determine the existence of the different phases by comparing the observed texture with data from previous X-ray studies.
As many as three mesophases were detected within the non-metal and zinc derivative compounds as they were heated.
Mesophases are the intermediate phases, between a crystalline solid in an ordered structure and a disordered liquid state. The scientists found changes in observable textures were a function of the heating/cooling rates used; for example when the C15 metal free derivative was cooled at 10°C min-1 the result was a needle like texture while slow cooling at 2°C min-1 resulted in a fan-like texture.
The Linkam hot stage is used with a microscope used to test the liquid crystal properties of some phthalocyanines. It is also used for basic melting point determinations.
The Linkam THMS600 stage can be used in many applications where high heating/freezing rates and 0.1°C accuracy are needed.
With a temperature range of - 196°C to 600°C, samples can be quickly characterised by heating to within a few degrees of the required temperature at a rate of up to 150°C min-1 with no overshoot, then slowed down to a few tenths of a degree per minute to examine sample changes closely.
The entire experiment can be saved as an online plot or exported to a spreadsheet application.
There are various options for this stage, including pressure, vacuum, electrical sample measurement and sample holders to mount the stage vertically in IR or x-ray spectrometers.
