Iodine-Induced Microphase Separation Controls the Flow Behavior and Electrical Conductivity of Silver-Filled Polymer...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Silver-filled polymer composites are vital for electronic applications like die attach and soft printed electronics.
• Achieving high electrical conductivity often requires high silver loading, increasing costs and limiting material properties.

Purpose of the Study:

• To investigate iodine-induced microphase separation of silver particles for enhanced conductivity in polymer composites.
• To reduce silver content while maintaining high electrical performance in conductive polymer materials.

Main Methods:

• Mixing micron-sized silver particles and three different iodine salts (1-butyl-3-methylimidazolium iodide, potassium iodide, sodium iodide) into thermoplastic polyurethane solutions.
• Characterizing the electrical conductivity, particle network formation, and surface properties using techniques like conductivity measurements, thermogravimetric analysis, infrared spectroscopy, and scanning electron microscopy.

Main Results:

• Electrical conductivity improved significantly, from 10^-5 S/cm to 500 or 2600 S/cm with 12 or 20 vol % silver, respectively, after iodine addition.
• Iodine effectively removed lubricants from silver particle surfaces, promoting stronger inter-particle attraction and microstructural heterogeneity.
• A paste-like suspension texture indicated a percolating particle network formation in the wet state.

Conclusions:

• Iodine modification is a cost-efficient strategy to produce high-performance conductive polymer composites with reduced silver loading.
• The method facilitates stronger silver particle attraction and improved conductivity, offering a straightforward approach for electronic applications.