Mechanochemical synthesis of core-shell carbon black@acrylic resin nanocomposites with enhanced microwave absorption

Abstract

For carbon black (CB) absorbers with high dielectric loss, improving the impedance mismatch characteristics is the key to achieving high absorption of electromagnetic waves. Herein, acrylic resin (ACR) is served as the matching layer for CB, and core-shell CB@ACR nanocomposites are prepared by a solvent-free mechanochemical approach. The ACR shell is an insulating polymer that can avoid mutual contact between CB particles to form conductive channels, resulting in the optimization of the impedance matching. Specifically, methyl methacrylate is firstly grafted on the surface of CB by ball milling to improve the compatibility between CB and ACR, and then ACR is wrapped on its surface using the same method. The measurement results show that the ACR is successfully coated on the surface of the CB, forming a core-shell structure with a 14.8–33.3 wt% encapsulation ratio. With a proper encapsulation ratio, the minimum reflection loss of the CB@ACR composites is enhanced by about 160%, the widest effective absorption bandwidth is widened by about 642%, and the corresponding thickness becomes thinner than pristine CB, achieving a “stronger, wider, thinner." In summary, this work provides an innovative and effective approach to modifying absorbers for excellent microwave absorption performance.