What is PCM?
A PCM is any material that undergoes a phase transition, expelling heat (energy) when it is cooled below a certain temperature. This is called the latent heat of fusion. Water is the most common PCM used in everyday life. Below 32°F or 0°C, water crystalizes into ice. The latent heat of fusion during this transition is 334 kilo-Joules of energy per 1 kilogram of ice, or more commonly written 334 kJ/kg (144 BTU/lb.).1.

Stirling Ultraguard closely aligns with dry ice, but does not require a regular supply of liquid carbon dioxide for production. Ultraguard is a non-toxic, salt-based PCM that if cooled below -86°C will transition from a liquid to a solid state with a latent heat of fusion of 190 kJ/kg (81.7 BTU/lb.).
Why is this important? Over the past few years, different geographical regions have encountered a carbon dioxide shortage, which in turn means dry ice supply issues.3 This became hypercritical when Pfizer, Moderna, and third-party logistics companies were trying to distribute COVID-19 mRNA vaccines across the globe at ultra-low temperatures.
How is PCM used?
There are multiple uses for PCM, as there are multiple types, with a range of storage temperatures. For ice, it is great to cool down your drinking water on a hot day or to hold on a sore muscle to fight inflammation. Ice also works great in a cooler to keep drinks cold at the beach.
Dry ice is often used when needing to keep a sample cold, for a limited period of time. Whether this be in a transport device or at a workstation, dry ice is used to keep the biological materials ultracold while being studied.
Introducing Ultraguard PCM for Ultra-Low Freezer Storage
Ultra-low temperatures below -60°C are difficult to achieve and maintain. Ultraguard, after being conditioned in a ULT freezer, may now help make these temperatures a bit easier to achieve. As BioLife Solutions explores new use cases for Ultraguard, we will be sure to keep you updated.
References
- “Change in State.” Residential Energy Library, https://c03.apogee.net/mvc/home/hes/land/el?utilityname=peco2&layout=IFrame&spc=hel&id=1702#:~:text=The%20heat%20given%20off%20in,144%20Btu%20per%20pound.
- “How Dry Ice Is Made.” CryoCarb, 8 Oct. 2020, https://cryocarb.com/how-dry-ice-is-made/#:~:text=Dry%20ice%20is%20made%20by,into%20pellets%20or%20large%20blocks.
- “US Faces CO2 Shortage.” Cen.acs.org, 17 Aug. 2022, https://cen.acs.org/materials/US-faces-CO-shortage/100/i29.