Ionic liquids as antistatic additives
We deal with static electricity every day. Combing the hair, shoes on certain flooring or carpets, sometimes we get little “electric shock” by touching door knobs. On the bigger scale though, for example for the industrial plastics, static electricity becomes more problematic, as the resulting charge on surface can lead to attraction of the dust and small objects to the surfaces, difficulties in further processing of the object and sometimes discharge with generation of sparks – an obvious fire hazard in some conditions.
Antistatic agents are used to combat this problem. They are typically distributed either in the bulk of the material or on the surface, and their role is to make surface more conductive, which helps to avoid surface charge build-up.
Ionic liquids have a set of properties that make them very useful as antistatic agents, including:
- Conductivity, that enables antistatic properties
- Thermal stability, that allows processing of polymer/IL blends
- Ultralow vapour pressure, which helps to avoid evaporation of ILs from the polymeric matrix, outgassing and release of VOCs
- Non-flammability, further improving the flame-retardant properties of the blend
- Good miscibility with the wide range of monomers and polymers, making them applicable to a variety of different plastics at different concentrations
- Wide liquid range, making handling and processing possible and easy in the wide range of temperatures
- Transparency, which allows application of ILs as antistatic agents for transparent polymers without loss of optical properties
- Hydrophobicity, which helps to avoid aqueous washing-out of the ILs from polymer matrix and makes antistatic properties independent of the atmospheric humidity, hence ILs can be used as antistatic agents in dry conditions.
ILs have been tested as antistatic additives to variety of plastics, showing reduction of surface resistance by at least the factor of 100. Using BMIM BTA in poly(methylmethacrylate) (PMMA) have not only helped to reduce electrostatic charge, but also rendered good transparency, which is of a great importance, as PMMA is used in optical fibres. The same IL was also used in polyurethanes. N1444 BTA showed good performance in polycarbonate (PC), while BMIM PF6 was compatible with poly(vinylidene fluorid) and TetradecMIM Br with polypropylene (PP).
At IOLITEC, we supply a variety of products that can be used as antistatic additives to plastics and other materials. We would be happy to discuss ionic liquids that would be useful for your specific application, so feel free to contact us, should you have any questions.
Text: Dr. Svetlana Cadu, Iolitec 2019