Hydro/Organo/Ionogels: "Controllable" Electromagnetic Wave Absorbers

Area of Science:

• Materials Science
• Polymer Chemistry
• Electromagnetics

Background:

• Growing demand for electromagnetic wave (EMW) absorbers in wearable electronics and military applications necessitates advanced materials.
• Current EMW absorbers face limitations that require innovative strategies for enhanced performance and tunability.

Purpose of the Study:

• To develop a novel strategy for creating high-performance, customizable EMW absorbers using functional polymer frameworks and immobilized liquids.
• To investigate the correlation between the dielectric properties of the gels and the characteristics of the immobilized liquids (polarity, ionic conductivity, non-covalent interactions).

Main Methods:

• Immobilization of strongly polar water, dimethyl sulfoxide/water mixtures, and conductive 1-ethyl-3-methylimidazolium ethyl sulfate ([EMI][ES]) within dielectrically inert polymer networks.
• Formation of hydrogels, organogels, and ionogels with precisely tuned dielectric properties.
• Characterization of EMW absorption performance, including shielding efficiency and effective absorption bandwidth.

Main Results:

• Hydrogels exhibited significant shielding performance (> 20 dB) due to high dielectric constants.
• Organogels achieved full-wave absorption in the X-band (8.2-12.4 GHz) with moderate attenuation and impedance matching.
• Ionogels demonstrated a wide effective absorption bandwidth (10.79-16.38 GHz) attributed to ionic conduction loss.

Conclusions:

• A versatile platform for developing high-efficient, customizable, and low-cost functional EMW absorbers has been established.
• The strategy allows precise tuning of EMW absorption properties by selecting diverse and stable immobilized liquids.
• This research opens new avenues for advanced materials in electromagnetic shielding and absorption applications.