(171b) Mechanically Robust Egyptian Blue Coated “Super Marbles”

Hydrophobic particles encapsulating a small volume of liquid (usually water or glycerol) is called a liquid marble (LM). LMs have received an increasing amount of attention in sensing applications in various fields recently and could be potential sensor candidates in water treatment. An ancient pigment, Egyptian Blue (EB, cuprorivaite), has also received increasing attention in sensing applications recently due to its intense near-infrared emission at 910 nm. To enable EB in sensing applications, a uniform coating of EB nano- or microparticles must be engineered. The uniformity of the coating will ensure the performance of the sensor’s coating. LMs are an excellent tool to prepare uniform coatings of nano- or microparticles. However, LMs break very easily under pressure. This severely limits their use in everyday applications. One possible way to overcome the breakage issue of LMs could be to introduce a more durable core. EB was exfoliated and then surface modified with trichlorovinylsilane to become hydrophobic. A drop of POLYCRYLIC topcoat or Gorilla Epoxy Glue was placed into the hydrophobic Egyptian Blue powder and rolled around to engineer a uniform coating around the marble. The marbles were allowed to harden overnight. SEM micrographs revealed large (1-250 µm) crystallite features, which did not allow for a uniform fluorescent signal. To get a more uniform fluorescent signal the hydrophobic EB powder was sieved through a 75 µm microsieve and “Super Marbles” were prepared with this powder, as well. Here we report the reaction conditions, synthesis, and SEM micrographs of such “Super Marbles” aimed at sensing applications, as well as their fluorescent emission in the infrared region.