A general approach to composites containing nonmetallic fillers and liquid gallium

Presenting a versatile method to make soft, deformable, functional metallic “putty” from liquid gallium and nonmetallic fillers.
We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O–containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal–based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific “fit for purpose” materials.